Tips for Successful Gardening in Colorado

By Education, Grow a Garden, Spring

Gardening in Colorado requires careful attention to seasonal variations, correct watering techniques and soil preparation. However, with 300 days of sunshine, disease problems are not as prevalent as in humid regions. Our semi-arid, mile-high altitude allows vegetables and flowers to mature quickly, with fruiting varieties, such as tomatoes, peppers and squash thriving in abundant light. For all gardeners, a little knowledge about basic gardening techniques and Colorado conditions can lead to a well managed, beautiful organic garden, with rich, productive soil and a diverse harvest.

Know When to Plant

The last spring frost is around May 15th, and the first fall frost is around October 5th.

Cool season crops, which can be planted as soon as the soil can be prepared (usually late March) include: spinach, onion seeds and sets, asparagus crowns, cilantro, parsley, potatoes, radishes, leaf lettuces, peas, green onions, collards and mustard greens. A few weeks later (mid-late April), plant carrot seeds and transplants of cabbage, broccoli and cauliflower.

Plant winter squash, pumpkins, corn, sweet basil, beans, cucumbers, and melons in the first week of May. Transplants of tomatoes are usually planted the second week in May, while heat-loving peppers and eggplants are best planted the third week in May.

Peas can be replanted at the end of July for a fall crop. Spinach, lettuce and radishes can be replanted in mid-August for a fall crop. Read individual seed packets for crop-specific information.


Prepare Soil with Adequate Organic Material 

Most Colorado soil is a heavy clay type, which needs to have at least 2 inches of compost dug into the top 3–4 inches of soil. Moisten soil a few days before digging and do not work the soil when it is wet, as it will dry like adobe brick.

Dig with a shovel or garden fork, turning over small clumps of soil at least 6 inches down, breaking up clumps with the shovel to produce fine particles. Spread compost on top of the loosened soil, again mixing it into the top several inches of clay soil (where most of the root growth occurs).

Plant Only What You Like and Can Care For

  • Plan enough space for cool, warm and hot season vegetables and herbs.
  • Utilize ‘succession planting’ for fast-maturing veggies such as spinach, lettuce and peas. To ensure a staggered harvest, plant small quantities of the above crops at 1–2 week intervals.
  • Interplant shade-loving veggies, such as lettuce, with taller peas. The peas shade the lettuce and also provide nitrogen needed by the salad green.
  • Leave enough space to replant spring crops in mid-August for a fall harvest.
  • Thin all direct-seeded crops to allow room for root development.

‘Harden Off ‘ All Greenhouse Transplants
For one week, expose all transplants to outdoor growing conditions. Take them outside in a semi-shaded area for 1 hour the first day and then bring them back inside. Each day, increase their time outside by 1–2 hours. By the end of the week transplants should be able to withstand strong winds and UV exposure.

Water Gently at Root Level
Newly planted seeds need daily watering, with uniform moisture applied slowly and evenly. Avoid overhead watering of tomatoes, cucumbers, beans, squash, pumpkins and melons, as diseases can be spread with such a technique. To find out if plants need water, insert a branch or your finger several inches into the soil, if moist soil adheres to your measuring device, plants do not need water.

Cultivate the Soil Around All Plants Once a Week
Lightly scratching the soil before watering is an excellent way to keep the weed population in check and open up air channels for deeper infiltration of water. A crumbly, loose soil also allows roots to reach down further for water. Weeds can be left directly on the soil and used as mulch. 

Mulch All Areas
Use straw or dried pesticide-free grass clippings as mulch around all crops. A light covering on all bare soil provides a cooler root-growing environment, prevents erosion and conserves water.

Harvest Frequently

Overgrown produce becomes a magnet for disease and insect infestation. Harvest when veggies are small and skins are shiny (especially noticeable in eggplants). As plants slow in production, remove the crop and plant a different variety. Early peas can be followed by squash, and spinach or lettuce can be followed by beans.

Integrated Pest Management Best Practices

By Education, Grow a Garden, Spring

Integrated pest management (IPM), encourages regular monitoring of insect populations to determine when and if treatments are necessary to minimize unacceptable levels of damage. It employs the use of physical barriers, companion planting and cultural techniques, in addition to least toxic controls to maintain a proper balance between pest and predator insect. In IPM, total eradication of pest populations is not sought, since it would upset the ecological balance. 

The individual needs to determine how much pest-related damage can be tolerated (the injury or damage level) without harming the health of plants or people is more important. Following this, the pest population must be studied to assess how rapidly it will increase to produce that level of damage. The final step involves development of a treatment strategy that will keep the pest population small enough so that it does not cause an unacceptable level of damage.

Companion Planting

As part of a well managed IPM system, strategies employing intercropping and companion planting are utilized to increase crop diversity. In this system, many different herbs, flowers and even weedy ground covers are used to deter pest insects and attract beneficial predators. Insects locate their preferred food by means of sight, smell and taste. They use sensitive receptors on their feet and mouthparts to find a certain crop from a great distance (e.g. the white cabbage butterfly can recognize the mustard oils of the broccoli family from a distance of ten miles).

Plants produce substances that either attract or repel insects. These include:

  • Attractants: Some examples include mustard oils of the brassica family that attract cabbage butterflies, apple skins attract codling moths and onions produce sulfur and attract the onion maggot.
  • Stimulants: These substances encourage feeding and/or egg laying behavior. Bitter chemicals in cucumber and melon skins stimulate feeding by the cucumber beetle.
  • Deterrents: These substances inhibit feeding or egg laying. Mustard oils sicken spider mites and Mexican bean beetles.
  • Repellants: These substances force insects to move away from a plant. Citronella and catnip sprays repel many insects.

Beneficial Insects to Attract

  • Ground beetles and lady beetles
    • Attracted by clovers, tansy and yarrow for egg-laying material; eat aphids, slugs and many soft-bodied pests.
  • Hover or syrphid flies (also known as flower flies)
    • Flat, open flowers such as marigolds or daisies provide areas for egg laying. Larvae control aphids.
  • Tachinid flies
    • White clover and members of the carrot family (e.g. carrots, parsley, lovage, queen anne’s lace and cilantro) provide sites for egg laying. Adults are parasites of Mexican bean beetles.
  • Lacewings
    • Increase in numbers when provided with nearby evergreens for shelter. Adults and larvae are fierce predators of soft-bodied pests.

Flowers and Nectar and Pollen for Adult Beneficial Insects
The compositae (daisy) family is attractive to most beneficial insects and includes daisies, goldenrods, black-eyed susans, coreopsis, asters, bachelor buttons and lettuces that have bolted (sent up a seed stalk). Other flowers and herbs that attract beneficial insects include bee balm, yarrow, the carrot family, mints, hyssop and salvia.

Legumes, such as peas or beans, are used as companions to increase nitrogen levels in the soil. White clover can be used in-between corn rows, as well as peanuts. Vetch can be used as nitrogen providing mulch around fruit trees. 

Beans: Plant rosemary, marigolds and nasturtiums to repel Mexican bean beetles.
Tomatoes: Good planted with basil (a possible fly repellant) and asparagus.
Broccoli family: Try with dill, mint, sage, onions and southernwood to repel cabbage butterflies.
Chamomile: Good hosts for hoverflies and wasps.
Cucumbers: Plant with marigolds and onions.
Peas: Plant with shade lovers such as spinach and lettuce.
Carrots: Plant with peas, leeks and onions.
Garlic sprays: Combine with hot peppers and onions (blenderized) for aphid control.
Catnip sprays: Try this for control of aphids and flea beetles.
Copper strips: To repel slugs. Also, try fermented yeast traps to attract and down them. Non-alcoholic Kingsbury Malt beverage was the brew of choice (or non-choice) that provided good slug control. Pull mulch away from transplants if the weather is rainy and slugs are congregating there. 

Specific Organic Remedies (Insects and Diseases)

Pest/Disease Crop Remedy
Aphids All crops Wash off with a strong spray of water, insecticidal soap.
Corn Earworm Corn Use a few drops of mineral oil in the tips of baby corn ears or dust with Diatomaceous earth.
Cut Worms All young transplants Protect stems with a ‘collar’ made of toilet paper cores. Utilize Diatomaceous earth on the soil around transplants.
Earwigs All crops Shallow containers of beer as traps.
Flea Beetles All young transplants Garden row-covers, such as Reemay, Safer Insecticidal Soap, Neem oil, Diatomaceous earth, beneficial nematodes (use the last product for juvenile forms of flea beetles that live in the soil), available as Scanmask from Planet Natural
Mexican Bean Beetle Beans (all types except soybeans) For adult beetles: Pyganic, an organic botanical product derived from chrysanthemums. For larvae: Neem oil. Both products are available at Arbico Organics 
White Cabbage Butterfly (Cabbage Worm) Crucifer family: Broccoli, cabbage, cauliflower, turnips, Brussels sprouts, Chinese cabbage, kale Brush off eggs that are mainly laid on the underside of leaves and also brush off the larval caterpillar form of the pest. Bacillus thuringiensis kurstaki (sold as: Thuricide or Dipel), which must be ingested by the caterpillars, so it is important to spray on the underneath leaf surfaces. Neem oil (available locally) can be used as a foliar spray. 
White Grubs All transplants and seeded crops  Eat germinating seeds and young roots. Use ‘Scanmask’ from Planet Natural.
Blights (spots, brown, yellowing leaves) Mostly tomatoes Pick off yellowing leaves, water at the roots. Use Serenade, available at Planet Natural.
Powdery Mildew Summer and winter squash, cucumbers, pumpkins and melons Water plants at the roots and discard severely infected leaves. Spray leaves with a solution of: 1 Tbsp. baking soda, 2 drops dishwashing liquid or Safer’s Insecticidal Soap, 1 Tbsp. horticultural oil such as ‘Sunspray R’, mixed in 1 gallon of water.

Sources: Carr, Anne. Rodale’s Color Handbook of Garden Insects. Rodale, 1979.
Cranshaw, Whitney. Garden Insects of North America: The Ultimate Guide to Backyard Bugs. Princeton, NJ: Princeton University Press, 2004.
Cunningham, Sally Jean. Great Garden Companions: A Companion-Planting System for a Beautiful, Chemical-Free Vegetable Garden. Rodale, 2000.
Riotte, Louise. Carrots Love Tomatoes: Secrets of Companion Planting for Successful Gardening. 2nd Ed. Storey Publishing, 1998.

Vegetable Planting Guide – A Guide to When to Plant What in Denver

By Education, Grow a Garden, Spring

For first-time gardeners or those new to Colorado, it’s helpful to understand a bit about our unique climate and growing conditions. Denver’s Climate & Elevation classifies as semi-arid high plain (Zone 6a). Although we receive 60 inches of snowfall per year in Denver, we only receive between 9-15 inches of precipitation usable for gardening.

We live at high elevation and enjoy over 300 days of sunshine with intense ultraviolet radiation annually. Gardening season in Denver runs from late March to late October. Please note, not all plants thrive in the same part of the season. Your seed packets will have specific information for each plant.

The average last frost in Denver is mid-May and the average first frost is mid-October. This determines the best times to sow seeds indoors or outdoors, depending on the crop and their preferred soil and air temperatures. It also guides us as to when to plant warm weather crops outside to avoid transplant shock and stunting due to temperature fluctuations and unexpected late-season snow. 

Knowing when to plant or transplant will help you and your plants prepare for a successful growing season.

Review the chart to explore when to plant different vegetables. Note whether they are considered ‘cool weather’ or ‘warm weather’ crops as well as whether seeds should be started indoors or directly sown into the soil.

warm weather
cool weather
sow indoors
sow outdoors
Start Seeds and Transplant * *Weeks before or after last frost date
Bush Beans  •  •  3-4 before  1-2 after 
Pole Beans  •  •  3-4 before  1-2 after 
Beets  •  •  2-4 before 
Broccoli  •  •  5-8 before  5-8 before 
Brussel Sprouts  •  •  5-8 before  4-6 before 
Cabbage  •  •  4-6 before  5 before 
Carrots  •  •  •  2-4 before 
Cauliflower  •  •  5-8 before  1-2 before 
Celery  •  •  8-10 before  2-3 before 
Chard  •  •  •  2-4 before 
Corn  •  •  3-4 before  1-2 after 
Cucumber  •  •  2-3 before  1-2 after 
Eggplant  •  •  6-8 before  2-3 after 
Garlic  •  •  6 before 
Kale  •  •  5 before, 2 after 
Kohlrabi  •  •  5 before, 2 after 
Leeks  •  •  8-10 before  5 before
Lettuce  •  •  •  2-4 before, 2 after 
Onion  •  •  3 before, 2 after 
Parsley  •  •  •  •  4-6 before  1-2 after
Peas  •  •  4-6 before, 2-3 after 
Peppers  •  •  1-3 after
Potatoes  •  •  4-6 before
Pumpkin  •  •  After frost
Radish  •  •  •  4-6 before 
Spinach  •  •  •  3-6 before 
Squash, Summer  •  •  1-4 after 
Squash, Winter  •  •  2 after
Tomatoes  •  •  2-4 after

Planting and Harvesting Tips

Bush Beans: Sensitive to transplanting, pinch extra plants. Don’t pull them. Pick every 3-7 days.

Pole Beans: Sensitive to transplanting; pinch extra plants, don’t pull them. Pick every 3-7 days.  

Beets: Thin when young and cook the tops as you would with other greens.  

Broccoli: Keep cool to get stocky plants, but don’t go below 40° F. Transplant into beds up to first true leaves. Harvest the main head when buds begin to loosen.  Side heads will form after the first head is cut.  

Brussel Sprouts: Keep cool to get stocky plants, but don’t go below 40° F. Harvest sprouts when they are 1 ½” wide. Pick lower ones first. 

Cabbage: Harvest when head is formed. Keep cool to get stocky but don’t go below 40° F.  

Carrots: Thin early; harvest any size. 

Cauliflower: Tie outer leaves around head to protect from sun. Likes weather between 57°- 68° F.

Celery: Must go below 60° F at night for seeds to germinate. Requires a lot of nutrients and water.  

Chard: Cut leaves close to ground when 8-10” high. Harvest outer leaves first.  

Corn: Sensitive to transplanting. Pinch extra plants. Plant in blocks; harvest when kernels are milky.  

Cucumber: Somewhat sensitive to transplanting; pinch extra plants. Mound soil into hills; plant 3 seeds per hill.  

Eggplant: Grows well in hot weather. 

Garlic: Harvest when tops start to die.  

Kale: Keep cool to get stocky plants, but not below 40° F. Cut outer leaves closer to the stem when 10” or longer.  

Kohlrabi: Keep cool to get stocky plants, but not below 40° F. Harvest when the bulb is 3” in diameter.  

Leeks: Keep cool to get stocky plants, but not below 40° F. Plant out when 4” high. 

Lettuce: Keep cool to get stocky plants, but not below 40° F. Hard lettuce likes repotting. Plant successively every two weeks. Will go to seed in high temperatures. Harvest outer leaves of leaf lettuce vs. head. 

Onion: Harvest when tips start to die back.  

Parsley: Soak seeds overnight to speed germination. Cut outer leaves near the stem.  

Peas: Sensitive to transplanting, pinch extra plants, don’t pull them. Harvest frequently.  

Peppers: Sensitive to cold, harden off gradually. Green peppers turn red when ripe. 

Potatoes: Very tender; cannot tolerate frost. Dig up with a digging fork after the tops have flowered.  

Pumpkin: Sensitive to transplanting; Pinch, don’t pull plants. Plant in hills, 3-4 plants per hill, 6-8 ft. apart.  

Radish: Plant every 10 days. Will get woody when over mature. 

Spinach: Keep cool for stocky plants.  Plant every 2 weeks. Will go to seed in hot weather.  

Squash, Summer: Sensitive to transplanting; pinch extra plants, don’t pull them. Harvest frequently.  

Squash, Winter: Sensitive to transplanting; pinch extra plants, don’t pull. Can store through the winter.  

Tomatoes: Prefers warm days and cool nights.

Adapted from Organic Gardening and Farming, February 1972, pp. 32-33, 54, and The  Encyclopedia of Organic Gardening, Rodale Press, Inc., 1978, pp. 233-235.

Specific Planting Dates for Metro Denver

On average, metro Denver sees our last frost for the season somewhere between May 15th and May 25th. However, in Colorado, we often see unpredictable weather in late spring and early summer, including snow in June! The table below lists the approximate dates for safe planting of vegetable seeds and pre–started vegetable plants.



Approximate Safe Date
Artichokes  May 15 to May 25
Asparagus from Seed  May 15 to May 25
Asparagus from Crowns  April 1 to April 30 
Beans – Bush & Pole May 15 to May 25 
Beans – Lima & Butter  May 15 to May 25 
Beets  May 4 to May 18
Broccoli  April 20 to May 5 
Brussels Sprouts  April 20 to May 5 
Cabbage from pre–starts  April 20 to May 5
Cantaloupe  May 15 to May 25 
Carrots  May 4 to May 18 
Cauliflower  April 20 to May 5 
Celery from pre–starts  May 4 to May 18 
Collard Greens  April 20 to May 5 
Corn  May 15 to May 25 
Cucumbers  May 15 to May 25 
Eggplant  May 15 to May 25 
Garlic  October/November 
Kohlrabi  April 20 to May 5 
Leek  April 20 to May 5 
Lettuce  April 20 to May 5 
Mustard Greens  April 20 to May 5 
Okra May 15 to May 25 
Onions for sets April 1 to April 30 
Peas  April 20 to May 5 
Peppers  May 15 to May 25
Potatoes   April 1 to April 30 
Potatoes – Sweet  May 15 to May 25 
Pumpkins  May 15 to May 25 
Radishes  May 4 to May 18
Rhubarb  April 1 to April 30 
Rutabaga  April 20 to May 5 
Shallots  Plant in fall or April 20 to May 5 
Spinach  April 20 to May 5 
Strawberries from crowns  April 1 to April 30 
Squash  May 15 to May 25 
Tomatoes  May 15 to May 25 
Turnips  April 20 to May 5 
Watermelons  May 15 to May 25 

5 Tips for Fall Gardeners

By Education, Fall Gardening

Mid–late summer is an excellent time to revisit the garden, review its successes and challenges and plan for fall – the season of renewal, regrowth and reimagining. Let’s look at some strategies that invite us to optimize the health and productivity of Colorado’s unique gardening season.

Tip #1 – Know When to Plant

  • Denver’s first frost can occur the first week in October
  • Check the maturity date (days to harvest) on the back of seed packets
  • Add the time needed for germination (usually 7 – 10 days), plus another 10 days to your time to account for slower growth with decreasing daylight hours

Planting techniques:

  • Plant slightly deeper than in spring to account for hot, dry soil, moistening soil prior to planting
  • Water consistently, in the cool of the day
  • Always water the roots and soil, not the leaves
  • Mulch planting area with straw
  • Spray with liquid kelp (1 tsp. kelp concentrate per quart of water)
  • Consider using shade cloth attached to a wooden frame for peas, lettuce & spinach

Tip #2 – Select Varieties Wisely

  • Crops either grown for a fall harvest or planted to overwinter & mature the following spring or early summer include: 
    • Seeds: leaf lettuces, spinach, arugula, mustard, radish, beets, peas, carrots, kohlrabi, green onions, cilantro (may overwinter to produce early spring crop)
    • Transplants: broccoli, cabbage, cauliflower, kale, brussels sprouts
    • Spring, early summer harvest: garlic
  • Choose the variety of seed or transplant that matures in the shortest period of time

Tip #3 – Remove Crops that are No Longer Productive

  • Any spring crops still standing in the garden (peas, radish, mustards, arugula, lettuce or spinach) should be removed, chopped up & used in the compost pile if not heavily infested with insects
  • Renew soil prior to planting & around established crops:
    • Spread around an inch of plant–based compost (such as ‘A1 EcoGro’) on vacant plot areas & around main season crops
    • Dig compost around 2” into bare areas & scratch several handfuls lightly into the soil around all remaining plants

Tip #4 – Save Space for Garlic

  • Garlic is best planted in early October
    • Either ‘hardneck’ (the kind that produces a flowering stalk called a ‘scape’) or ‘softneck’ (the kind usually found in grocery stores & used for garlic ‘braids’) can be planted
    • Carefully separate the bulb into individual cloves, using the largest cloves for planting & smaller ones for eating
    • Leave the papery skin intact & plant in compost–enriched soil, 3 – 4” deep,  4 – 5” apart in full sun
  • Mulch with several inches of loose straw or chopped leaves (run over them with a lawnmower) if planting after leaf drop
  • Water well several times over the winter if we don’t have adequate snow cover

Tip #5 – Plant Fall Cover Crops

  • Grains such as winter rye and legumes such as hairy vetch are planted, often mixed together to cover the soil like a blanket, preventing soil erosion
  • Their roots improve soil structure, opening up air channels that promote deeper rooting for subsequent crops & also provide nutrients that benefit soil microorganisms
  • They can serve as habitats & food sources for beneficial insects
  • They keep weed species in check by covering the soil surface & decreasing sunlight available for weed germination

Planting techniques:

  • Plant by mid–late September
  • Follow directions on the cover seed packet regarding amounts to plant
  • Rake seed lightly into the top ¼ – ½” of soil, lightly pressing it in with a hoe
  • Cover with a light layer of straw or chopped leaves
  • Water 

Early spring care:

  • Cut down the cover crop before it reaches knee – high, leaving the top growth on the surface as a mulch & the roots in the ground. 
  • Wait 2 weeks for decomposition to occur prior to planting spring seeds
  • Enjoy your best garden ever, knowing that you have worked to prepare fertile, moisture–retentive, biologically alive soil

How To Grow Garlic

By Education, Fall Gardening


Garlic likes full sun and well-drained soil. Garlic is quite tolerant when it comes to soil types and textures, but it definitely appreciates sandy-clay-loam that is friable (easily crumbled in the hand) and has a high organic content. It does best when the pH is in the 6.2 to 6.8 range. The garden or field should drain easily – standing water just won’t cut it as the bulbs could rot in the ground. To increase the tilth of the soil, add organic matter such as well-composted manure. You can also green mulch, which is planting cover crops such as clover or buckwheat and then tilling them under.


If you have a small plot, spade up the top 6 to 12 inches. Garlic roots like to go deep, so well-cultivated soil is a big help. Mix in the organic matter and manure at this phase. After the deep tilling, we find a final pass with a cultivator that powders up the upper several inches of the soil aids in planting.


When to plant? The fall is best. Remember garlic is a bulb (like tulips and daffodils). Plant 4 to 6 weeks before significant ground freezing may occur. On the High Plains, we like to get going by mid-September, since snow by the end of September is not at all that rare here. The idea is to get the cloves in the ground during warm weather so germination occurs and good root formation follows. It is good sign when you get green shoots popping above the soil in late autumn. Don’t worry. The tips may suffer a little winter burn, but they can tolerate zero and below.

When do you “crack” the bulbs? Since one obviously does not plant the bulb whole, you must crack (split) the wrapper and separate the individual cloves. It is best not to do this more than about 48 hours before actual planting, or they will begin to dry out and lose viability.

How deep to plant? We find the tips should be about 2 inches below the soil surface. For elephant (Buffalo) garlic, make that 3 to 4 inches. Be sure to plant with the pointy side up/basal plate (root) down.

How to plant? In dry climates we find it works best to let the upper few inches dry out and then bring in the cultivator. Then you can literally just stick the cloves in the ground by hand and the soil covers them up as you remove your fingers. If you have heavier and/or wetter soil, you can poke a hole in the ground with a broom handle and just drop the cloves in the hole, covering up the entire batch with a rake at the end. This works best if you water the soil several hours before planting so it is moist but not muddy.

How close do you plant them? Our experience is that closer is better. But the cloves should have enough room to grow into large bulbs (at least 4 to 6 inches for hardneck and 6-8 inches for elephants). The close planting helps with weed control once the plants get larger in spring as the leaves block out the sun to the later sprouting weeds. If you plant in rows, be sure to leave enough room (24-30 inches) in between so you can get in there to weed next spring. 24 inches wide by 21 inches long would fit approximately 20 cloves. They would be 6 inches apart going across and the rows will be 7 inches apart.


This is a key element to real garlic success. Mulch serves many purposes, not the least of which is to regulate the sharp changes in temperature and moisture that can occur during winter, especially out west. But it also goes a long way towards controlling weeds the next spring. Mulch can be straw or alfalfa. Lawn grass clippings are excellent. Chopped leaves will work if you have them. Wetting down your mulch helps compact it, making it less likely to take off. You should plan to put the mulch on immediately after planting (perhaps after giving the ground a really good watering). Don’t be shy on the mulch, at least several inches should cover your crop. You would be surprised how tough those shoots are when it comes to punching through the mulch. If you do mulch extra heavily, removing some of the overburden in spring might be a good idea, but leave enough for weed control.


Most of the time it really likes moist (not soggy) soil. Watering regularly in the fall during germination is essential. In dry climates, watering in winter is also important. Keep on watering into the spring when the maximum green shoots are forming. Then about mid- to late June, or when the scapes (on hardnecks) are standing high, STOP. During the last four weeks, when the bulbs are finishing off, and the wrappers are drying out, too much water is not good. You can create a mold or fungus problem.


When to harvest? When the lower third to half of the leaves have turned brown, but there are still mostly green leaves higher on the plant, it’s time to harvest. You can always test dig one or two plants. On the High Plains, depending on the weather, harvest can begin as early as the first week of July. There is also a two to three week difference in the harvest dates of the several varieties. To get the bulb out of the ground, don’t just try to pull them. The stalk will break. You must dig, using a pitchfork or the like in order to loosen the soil. Then you can lift the entire plant out of the ground.


If you want to store your garlic, you have to cure it first. After the curing process they store up to six months. The entire plant, leaves and all, should be dried out for about two to three weeks. The drier your climate the faster the curing will go and the less chance you will have to deal with mold. The simplest is to tie up a bunch with string/wire and hang them in a well ventilated place. Do not wash your bulbs or let them be exposed to water. You can also pack them loosely into large mesh bags or in open sided crates. But they must get a lot of air circulation. After the curing is complete, lop off the tops about an inch above the bulb and trim the roots.

Storing garlic requires an even temperature (50-70°F seems to work) and a relative humidity averaging in the 50-60% range. Make sure they get plenty of air circulation. Most hardneck garlics and elephants can be kept for several months. The softneck varieties do tend to have a somewhat longer shelf life.

Fall Cover Crops

By Education, Fall Gardening

Cover crops consist of many different types of plants, usually annual, biennial or perennial grasses or legumes, which are grown to cover the surface of the soil.  After they are tilled or dug into the soil, they are known as ‘green manures’.  


  • Cover crops act like a blanket, preventing soil loss from wind and water erosion. 
  • Their roots hold the soil in place and help to improve soil structure. During the process of decomposition, microorganisms and the decomposing cover crops produce sticky substances that glue soil particles together.  This opens up air channels and also increases the water holding capacity of the soil.
  • Cover crops keep weed species in check by covering the soil surface and decreasing sunlight available for weed seed germination. Additionally, some grasses, such as winter rye exhibit a property know as ‘allelopathy’. Their roots, when tilled into the soil, prevent seeds from germinating until the plant has decomposed.
  • Crops in the legume family, such as hairy vetch, planted with specific types of bacterial inoculants, have the ability to develop special structures on their roots that store nitrogen and make it available as the crop is dug or tilled under.
  • Many cover crops reduce pest insect populations by serving as habitats and food sources for beneficial insects.


Crop and Planting Specifics

  • Best choices for fall planting include Winter Rye and Hairy Vetch. Often a mix of rye and vetch is planted. Austrian winter pea is slightly less hardy.
  • Plant by mid – late September as crops are harvested. Small amounts of the above varieties can be obtained from local garden centers. The mixes can also be ordered from Peaceful Valley Farm and Garden Supply:       
  • Prepare seedbeds by digging thoroughly, adding an inch or so of decomposed compost mixed into the top 4 – 6 “ of soil. Make sure large clumps or clods are broken up.
  • Water the area well prior to planting the cover crop seed.
  • Follow directions on the seed package for seed sowing (Winter rye: 4 – 6 oz per 100 square feet, Hairy vetch: 2 – 3 oz per 100 square feet).
  • Rake seed lightly into the top ¼ – ½” of soil, lightly pressing it in with a hoe.
  • Cover with light layer of straw or chopped leaves 

Early Spring Care

  • Cut the rye before it reaches knee – high, then dig or till or crop remains in.
  • Wait two weeks for decomposition to occur prior to planting spring seeds
  • Enjoy your best garden ever, knowing that you have worked to prepare fertile, moisture-retentive, biologically alive soil.

Learn more about how to plant cover crops with Brit + Nessa!

Constructing a Hoop House for Season Extension

By Education, Fall Gardening

Supplies Needed

Note: This list provides everything you will need to build a hoop house large enough to cover a 4’x8’ raised bed. 

  • 4-5 – 10’ pieces of ½” PVC piping 
  • 2 – ½” PVC caps
  • 1-1/4 in. Ratcheting PVC Cutter
  • 3 – 1 ⅜” x 2 ½” U bolts or Tape
  • Hammer
  • Bricks, large stones, or weights (1-2lbs) at least 6 for each bed
  • 6-12 Spring Clamps 
    • You may not always need all 12 of these, or this specific model, but whatever you buy make sure they have rubber tips to protect against tearing the plastic and that they are strong enough to secure the sheet during high winds. 
    • Option: you can buy flexible rubber tubing to cut and secure around the pvc to prevent tearing when clamping the plastic sheeting to the frame.
  • 6-8 pieces of 24 inch rebar (# of pieces dependent on how many frame bars you use)
      • They sell this in bundles of 6 at 24” per piece. Otherwise you will have to cut them down to the desired length – the next size down in the pre-cut bundles is 12″. Some shops may cut this for you. Home Depot and Lowes will not.
  • 4-6mil plastic sheeting or light row cover (Amazon has numerous options for varying thicknesses)
  • Plastic sheeting: Anything in this range will provide the cover you need while still allowing light in. However, the thicker the plastic, the harder it can be to manage and the heavier it is, which may be a factor with heavy snow and cold temps providing sturdier protection and insulation
  • Row Cover: This product is great for shoulder season frost protection, but should not be considered safe cover for plants when temps dip over 4-5 degrees below freezing for extended time periods. For long-term season extension plastic covering is recommended. 


Step 1 – Decide on your spacing for the main frame pieces and measure/mark their placement.

For this build we will space enough for three frame bars. One on each end of the bed with a single bar spaced equal distance in the middle of the bed. Note: For a 4’x8’ bed It is recommended that you do at least three cross bars for support, this will help safeguard against collapse in the case of severe weather.

Step 2 – Hammer your rebar pieces into place where you marked for the frame.

You can place these on either the outside or inside of the bed. For this build we will place the rebar inside the bed, up against the walls of the frame. Leave at least 6 inches of rebar exposed above the surface of the soil.  Note: This will all depend on the height of your bed borders, you do not want rebar exposed far above the top of the bed. This is a serious safety hazard. You want to make sure you have enough rebar exposed to secure the frame. If you have a low-sitting bed and have no choice but to leave some rebar exposed, be sure to remove the bar whenever you remove the frame for the season to reduce the chance of injury. 

Step 3 – Lay one 10’ piece of PVC the length of the bed, mark both ends 1 inch past the inner length of the bed, and cut accordingly.

This will act as the ridge bar that runs the top length of the cross bars. It will work as the main support beam for the main frame. 

Step 4 – Cut your cross bars to a length of your choosing.

For a 4’x8’ bed, it is recommended that you cut them no less than 6’ and no more than 8’. Less than 6’ and you limit your space, while more than 8’ can cause the frame to become less stable and more vulnerable to wind. 6-7’ is the sweet spot.

Note: The length of the cross bars will vary greatly depending on the size of your bed. 6-7’ may be too large for a smaller bed, say 3’x6’. Knowing what you’ll be planting and the size of your bed will help you make the proper height adjustments. If you are unsure and not interested in math equations, take the pvc pipe and attach it to one side of the rebar. Hold it in place, bend it over the bed, and measure how high you want it. Be sure to apply this same measurement to all cross bars. 

Step 5 – Place the PVC caps on both ends of your ridge bar to protect the plastic from tearing against the frame. 

Step 6 – Run the ridge bar the length of the bed and attach it to the underside of each crossbar with the U bolts.

The open U side should be facing down towards the soil, with the smooth U bend on top of the PVC. If you do not have the bolts or do not want to use them, you can use a variety of tapes, or other fasteners. 

Step 7 – Measure and cut your plastic sheeting.

Measure the length of your cross bars (in this case – 6’) and the length of your bed (in this case 8’). Use these two measurements to cut the width and length of your sheet. Be sure to add enough to both measurements to account for the height of the bed itself. If the walls of your bed are 6” above ground, add 8” to both the width and the length. You want to ensure that you have enough extra sheet extending to the ground with a bit extra to spare. The extra plastic will allow you to use weights to secure the sheet on the ground around the edge of the bed. 

Note: If you really want to ensure you’re cutting perfectly, you can take the frame pieces and lay them out on top of the plastic, just as they were spaced in the bed, then cut, again, being sure to account for the extra you’ll need to cover the bed frame.  

Step 8 – Place the sheet covering over the frame and even it out on all sides.

Use your clamps to secure the plastic to each crossbar. Attach the clamps to the crossbars down near where they intersect with the bed frame to create a partial seal around the edge of the bed. Use your weights, bricks, or other heavy items to secure the extra sheet around the base of the bed, especially in the front and back where you will enter and where the plastic covering is most vulnerable. 

Note: You may need to add more clamps to the frame as the weather dictates. Colorado is becoming an increasingly windy environment and wind is a hoop house’s arch nemesis. 

6 Things to Consider When Turning a Lawn Into a Garden

By Boundless Landscapes

I’ve made every gardening mistake in the books so you don’t have to!

By Jennifer “Fern” Deininger, Farmer & Gardener

When walking around the Front Range you may have noticed a significant number of homeowners transitioning their front yards into xeriscapes, vegetable gardens, perennial habitats, or pollinator gardens. There is an increasing number of first-time gardeners in the United States, and with that many homeowners have begun to replace parts of their yard with more environmentally- and socially-beneficial landscapes.

In fact, based on research from Bonnie Plants, more than 20 million Americans planted a vegetable garden for the first time during the COVID-19 pandemic.

For years I’ve worked with homeowners to turn their lawns into gardens and food-producing micro-farms, so below I’ve shared six things to consider before taking the leap.

1. Consider how light and water move across your landscape. Food-producing gardens often need 6+ hours of sunlight per day. When picking a spot to install a raised bed or plant your in-ground garden, look up. Try picking a spot that won’t be obstructed by large trees or shade from a house. If you’re doing this in the winter, keep in mind that your trees will likely cast even more shade once they grow their leaves in the spring. You’ll also want to consider how water moves across your landscape. I recommend picking a relatively level spot if you’re creating an in-ground bed or taking the time to carefully level your raised beds if you’re building a raised-bed garden. It makes a huge difference! If you’re planting in-ground, selecting a location where water doesn’t flow too quickly across your garden area in a rain storm will help slow erosion and prevent run-off from any fertilizers you use. Similarly, if you can avoid planting in the lowest spot on your property, then your garden will be less likely to flood in a rainstorm. 

2. Pick no more than one big landscaping project each year to make your installation more manageable. It can sound really enticing to go from lawn straight into having a beautifully planned garden with lush raised beds, trellises, mulched walkways, and mature perennial plants, but all of these things take time, money, and resources. I recommend homeowners start with one big project per year, whether that is removing the lawn, installing a few beds, or purchasing and planting ground cover. Perennial plants can be expensive and take a few years to establish, but purchasing a few every year will prevent overcrowding and is easier on your wallet! I recommend starting with projects that address the layout and infrastructure of your garden. This may include building raised beds, installing irrigation, removing your lawn, etc. 

3. Plan for visitors! I always try to plan for what sorts of beings may be visiting the garden. Whether it’s children, dogs, deer, aphids, bunnies, or squirrels, knowing in advance who is likely to visit your garden can help you select the right plants and the right protection. If children will be around, stay away from any perennials that may be toxic like sweet peas or foxglove. If you have deer that come around, try planting a border of deer-resistant plants like lavender, columbine, and larkspur. If you have a dog that loves to dig, then you may want to consider a tall raised bed rather than an in-ground garden. If you’ve noticed you have a large number of pests like Japanese beetles or aphids, planting insectaries (plants that attract beneficial insects) like cilantro, dill, cosmos, coreopsis, and yarrow is helpful!

4. Have a plan for irrigation before you dive in! Many perennial plants need frequent irrigation for at least the first few years in a garden and annual vegetables may require irrigation every day or every other day depending on many factors. Irrigation can seem daunting, but there are many great ways to water your garden (aside from lugging a watering can or hose around). Whether you tap into an existing irrigation system at your home, install a whole new one, or add a timer to a spigot and run your irrigation from there, I recommend reaching out to a professional who can help with the design and the installation. Irrigation mistakes can be costly and can cause damage and flooding in your home, so make sure to speak with a pro before diving in. 

5. Protect the soil! Healthy soil is the foundation of any garden. When removing your lawn, try to avoid compacting the soil or letting it sit bare in the hot summer sun. Soil needs air, water, and nutrients to be happy. Whether you’ll be planting in-ground or in a raised bed, I recommend aerating the soil and adding two inches of high-quality compost in the spring and fall. If you’re looking for a soil-friendly way to replace your lawn with a garden, feel free to check out our other blog post about sheet mulching! *Link to sheet mulching

6. Call before you dig! Call 811 a few business days before any projects that involve digging. Whether you’re planting a young tree or installing a fence, call 811 to make sure your underground utilities are flagged appropriately. 

I hope these tips help you make smart and budget-friendly decisions when considering turning your lawn into a garden. If you have any questions about taking this step, we offer garden-coaching sessions at Boundless Landscapes to help empower homeowners to get outside and try something new. We’d love to support you!

Sheet Mulching to Remove your Lawn: Why, When, and How

By Boundless Landscapes

I’ve made every gardening mistake in the books so you don’t have to!

By Jennifer “Fern” Deininger, Farmer & Gardener

Sheet mulching, also known as lasagna gardening, is an environmentally regenerative, relatively easy, and financially accessible way to turn a lawn into a garden. Sheet mulching doesn’t involve the use of machinery or tilling, but rather is a method of layering materials in your garden that compost in place (or “cook down”) over time to produce a rich, fluffy topsoil that is perfect for planting vegetables, flowers, and herbs.

Sheet mulching can be used to fill a shallow raised bed, replace a patch of lawn with healthy soil for an in-ground garden, or kill weeds around perennial plants.

After the initial work of sourcing and laying out the ingredients, the sheet mulch breaks down over a period of a few months. (The sheet mulched area will need a few months to decompose before planting it up.) Rather than having a patch of your garden covered in compost, grass clippings, and leaves over the peak growing season, I recommend starting this process in the fall and letting it decompose over the winter. Before we talk about how to do it, it’s best if we cover a bit of compost 101.

Composting is a process in which organic materials are broken down by microorganisms in the presence of air (oxygen) and water. Given enough air, water, and microorganisms, the organic materials turn into a rich mixture of nutrients and good bacteria. Compost holds water much more efficiently than regular soil or bagged gardening soils and sinks carbon into the landscape. Compost requires browns (carbon-rich items like black and white newspaper, dried leaves, sawdust, and straw) and greens (nitrogen-rich items like green grass clippings, pruned parts of your vegetable plants, uncooked vegetable scraps like the tops of a carrot, and coffee grounds) with at least three times as many browns as greens.

When sheet mulching, we layer “greens” and “browns” that then decompose and compost in place over time. If you were to cut into your freshly laid down sheet mulch, it would look like a lasagna or layer cake, but over time it turns into a fully integrated mixture of compost that is perfect for planting. It’s important to note that the sheet mulch will also shrink down over time, meaning if you start with eight inches of material, it will decompose into a few inches of soil over time.

Once you’ve decided where you want to sheet mulch, it’s time to layer!

Layer 1: Start with a layer or two of brown cardboard. This cardboard will suppress weeds and grass, retain moisture to aid in the composting, and is a great snack for our beloved friends, the earthworms! Watering the cardboard will help it stay down if you’re working on a windy day and will help it decompose faster. It is important to remove all staples and non-compostable tape from the brown cardboard prior to use. The cardboard you use should be brown, rather than dyed.

Layer 2: Add half an inch to an inch of greens. Grass clippings are readily available and work well. It’s best to use grass clippings free of pesticides and pet waste, so source carefully.

Layer 3: Three inches of browns, such as straw, fine wood chips, and black and white newspaper shreds. Just make sure you don’t use hay, which often has seeds in it!

Layer 4: Repeat with greens and browns until you’ve reached the desired depth.

Top Layer: The top layer should be a mixture of topsoil, compost, and mulch. 

Make sure to water your sheet mulch heavily and leave it to decompose! Topsoil and compost are readily available at landscaping supply centers and local nurseries. If you plan to do a large area, consider using a garden calculator to figure out how many cubic yards of material you will need. 

In an arid climate like Colorado where topsoil can take a long time to form in nature, sheet mulching is a great way for homeowners and gardeners to maximize their positive impact on their ecosystem.

It can take 100-1,000 years for one inch of topsoil to form in nature, but by sheet mulching, we can help speed up that process to a few months. Due to the dry nature of our ecosystem, sheet mulching works well when done in the fall so it has ample snow and moisture over the winter as it cooks down. Come early summer, your garden will have shrunk down in size, composted in place, and it will be ready for whatever is next!

Note: Do not add any meat, dairy, oil, eggs, or manure to the garden beds.

You can book One-on-One coaching sessions at where $5 from every session will be donated to DUG. Happy growing!

Growing Gardeners with DUG featured in USDA Farm to School Newsletter

By Education, News

DUG’s new ECE Growing Gardeners Initiative brings younger children into the garden.

.The National Gardening Association reports huge increases in the number of people engaging in gardening, documenting over 18 million new gardeners in the US in 2021. Gardens encourage us to ‘slow down’ and appreciate the interconnected community of soil, plants, and critters while improving our mental health and wellbeing. For children, the garden provides opportunities for cultivating the wonder and joy of experiential learning while connecting to our lifegiving earth and soil.

Denver Urban Gardens’ (DUG) Growing Gardeners Initiative, a Fiscal Year 2021 Farm to School Turnkey Grantee, creates a system of resources for bringing younger children into the garden. Hands-on DUG lessons investigating composting worms under magnifying glasses, engaging in cooking and trying new foods in garden clubs, and planting seeds and seedlings for the season provide students with memorable time in the soil.

Studies show that exposure to gardens at a younger age increases the chance that children will continue to value healthy eating and gardening into adulthood. Working with a cohort of twelve Denver Public Schools early childhood educators, DUG provided year-long training to increase teachers’ comfort level in taking students outside and integrating gardens into their curricula.

The initiative’s first year has been a great success thanks to the commitment of these teachers. Additional lessons, webinars, and video content will be made available on upon completion.

Children need unstructured physical activity. As they work to turn the soil and care fortheir baby plants, gardens serve as both guardian and nurturer–an outdoor classroom with quiet, secret places that allow kids to discover that as they care for a plant, they are also protected. They learn the importance of self, that their efforts are important, and that working together and respecting diversity is part of the process of growth.

Moving forward, DUG will support a new cohort of teachers with year-long programming.  Local grant funds will further deepen our efforts by incorporating sensory garden plots at selected DUG school-based community gardens.

Check out DUG’s feature in the USDA Farm to School newsletter here.