Starting your own seeds might seem complicated at first, but the benefits are well worth it for many gardeners. Not only will seed starting allow you to grow a wide variety of plants that you might not find in stores, it will save you money, too. Growing your own plants from seeds also ensures that you have the right amount of plants for your garden —or provides a great opportunity to grow more to share with your friends and neighbors.
What You’ll Need
Light
Some seeds require light to germinate, while others prefer total darkness. Your seed packet should tell you what your seeds’ requirements are. However, once germinated, all seedlings need light to develop into strong, healthy plants. New seedlings thrive in about 16 hours of light. Ideally, you will have space to hang fluorescent or LED light fixtures from above with ample space to place your seedlings in trays or flats. If you do not have grow lights, do not let this stop you from growing inside. Select a spot where there is bright light—a south-facing window is best.
Containers
You can start seeds in just about any kind of container, as long as it is shallow. Trays, flats, pots, old egg cartons, cut-off milk cartons, or even toilet paper rolls are suitable. Try all kinds of containers to see what works best for you. Make sure they are clean and have good drainage at the bottom. Poke holes into the bottom as needed. If your trays or pots are old, it is a good idea to soak and clean them in a solution of 90% water and 10% bleach to sanitize before using. If you are using a fiber or peat pot, soak well with water before adding soil —dry fiber pots draw moisture away from the soil.
Seeds
This is where the fun begins—you can source seeds for so many exciting varieties both online and in local gardening stores. You will get the best results if you obtain fresh seeds that were packaged for the upcoming growing season. If you have saved seeds that you purchased last year, be sure to test the germination rate before planting. You’ll want to see at least a 70% germination rate to ensure the seeds are viable for the growing season.
Growing Medium
Choosing the right growing medium is essential to success, and it’s important to use a ‘soilless mixture’ designed for starting seeds. Look for mixes designated as ‘germinating’ or ‘seed starting’ mixes that contain ingredients like peat moss, coco coir, perlite, and/or vermiculite. Avoid products labeled as ‘potting soil’ or ‘garden soil’ for germinating your seeds. We recommend Espoma Organic Seed Starting mix.
What Seeds to Sow
Seeds that benefit from being started indoors include the cabbage family (cabbage, broccoli, cauliflower, and kale), onions, tomatoes, eggplant, tomatillos, and peppers.
You can start others, but it is not necessary. Cool-season crops (peas, lettuce, spinach, root crops and more) can be sown directly into the garden as early as April. Cucumbers, squash and beans can be planted directly into the garden in mid to late May. Reading the seed packets will help you determine what to plant and when.
Getting Started: Sowing Your Seeds
Fill your containers to ¼” from the top with your potting mixture and level the surface. Be sure to water the soil and allow it to drain thoroughly before sowing the seeds. Make a hole for each seed with your finger or a pencil. Keep in mind that most seeds need to be planted two to three times as deep as the seed is wide. If your seeds are very fine, cover them with a fine layer of soil. Afterward, place your containers with drainage holes on a shallow tray that will allow you to water them from the bottom so as not to disturb your new germinating seeds.
Germination Time: Watch For Moisture and Humidity Levels
While your seeds are germinating, they should be kept evenly moist but not soaking wet. Too much moisture in your soil mix will cause the seeds to rot. Use a fine sprayer to water newly planted seeds and tiny seedlings or, if possible, water from the bottom. We recommend you place your pots and flats into plastic bags or use a humidity dome to keep the humidity and moisture even while also reducing the frequency of watering. Remove the clear humidity dome daily and lightly blow on the soil, replacing the dome after you do this. Carbon dioxide decreases seed germination time. Check daily for seed germination. As soon as the first seeds in the flat have emerged, remove the clear humidity dome and leave it off.
Grow, Baby, Grow: Seedling Care
The care you give your seedlings in the weeks following germination is critical. Continue to keep the soil moist but not soaked. Use warm water to water the seeds for the first two or three days. Once the seedlings have germinated, use water that is just a little warmer than room temperature. Continue to water from below.
Small pots and flats dry out quickly, so check their moisture levels often. To check, stick a sharpened pencil into the soil about a quarter inch; if moist soil sticks to your pencil tip, you do not need to water. If your seedlings are growing in a windowsill, turn often to encourage straight stems. If you are using grow lights, keep lights directly above the plants once they are germinated. The lights should be almost touching about 2-3” above the top of the plant. Raise the lights as the plants grow to maintain proper distance.
After seedlings have been growing for several weeks (assuming both seeds in each cell have germinated successfully), use a small scissor to cut the weaker seedling off as close to the soil as possible. Choose the shorter, stockier seedling to leave in each cell. While this might feel painful to do, your seedlings must have enough space to grow into healthy plants.
Preparing For The Garden: Hardening Off
After about 6-8 weeks, your seedlings will be at the right stage to transplant. Ideal seedlings will look short and stocky with sturdy stems and strong roots. About one week before you want to transplant your seedlings outdoors, start to ‘harden them off.’ This process acclimates the soft and tender plants, which have been protected from wind, cool temperatures, and strong sun, to their new environment.
Move the plants to a shady outdoor area at first and bring them indoors for the night if night temperatures below 55 degrees. Each day, move them out into the sun for a few hours, increasing the time spent in the sun each day. Make sure they are protected from wind, too. Keep them well watered during this period and do not place them directly on the ground if slugs are a problem. Monitor them closely for insect damage, since tender young seedlings are a delicacy for insects.
Time To Transplant
Do not be in a rush to put your plants in the garden. If they will not withstand frost, be sure all danger of frost has passed before setting them out.
Water the ground outside and the seedlings thoroughly before transplanting. This helps prevent transplant shock. It is preferable to transplant on a cloudy day so strong sun will not wilt your seedlings. Very gently remove your seedling from its container, being careful to not pull out your plant by the stem.
Dig a hole about twice the size of the root ball and set the transplant into the hole so the root ball will be covered by ¼” of soil. Press the soil firmly around the roots. A small depression around the plant stem will help trap moisture. Water immediately after transplanting and every day for the first week. Be sure to water deeply so your plants will not develop shallow roots.