I just took a bite of my first radish that I started from seed and it was so satisfying! So I thought I’d share the steps to growing seedlings with you so you can experience the same satisfaction this season. It’s so easy to practice manual literacy my friends, and you won’t regret it. To unlock a seed from its dormancy, it needs four things: water, light, oxygen, and the right temperature.
Warm-weather crops like tomatoes, melons, eggplant, and peppers need to be started indoors so they have enough time to bear fruit before the cold weather sets in. Other plants, notably root crops like carrots and parsnips, should only be sown directly in the ground since they don’t like to be disturbed once they germinate. If you have started seeds in plastic flats, they will need to be transplanted twice: first, when leaves appear, into larger containers so that they have room for their roots to grow, and second, into the ground.
Steps to Growing Seedlings:
Begin Indoors
If starting the seeds indoors, fill the containers with soil mix. The best combination for seeds includes not just straight potting mix, but equal parts potting mix, humus, and vermiculite. Tamp it down gently, leaving ½ inch or so of space at the top.
Moisten the Soil
Moisten the soil before you sow. It should be sponge-damp but not soaking wet. This applies to both outdoor and indoor planting. Maintain consistent moisture. For plants that you germinate in pots, it is ideal to water them from below by setting a tray under the pots and filling it with water. The soil will soak up the water through the bottom of the pots. If you can’t do that, a delicate sprinkling with a watering can will do.
Sew Your Seeds
Check the seed packet for information on how deep and far apart to sow the seeds. As a rule of thumb, the bigger the seed, the deeper it needs to be planted, at a depth of about twice their diameter. Lettuce seeds, for example, should just be barely scratched into the surface of the soil, whereas bean seeds need to be covered with an inch of soil.
Label Your Containers
Label your containers or rows so you can keep track of what they are.
Set Them In A Warm Bright Area
Place the seed containers in a warm, bright area. Most seeds germinate best in temperatures from 60°F to 75°F. Put them on top of the fridge or in a sunny window. If you cover them with a clear dome or plastic bag they may not need to be watered again until they germinate. The surface of the soil should feel damp not wet, so if you do water, do it gently. A kitchen sink sprayer is a good option.
After seeds have emerged, give them a lot of light, otherwise they grow leggy, meaning tall, thin, and weak. Seeds can get plenty of heat but without light they will become floppy. This can sometimes happen when seeds are started too soon in the spring season. Fluorescent tube grow lights come in handy here. But if your seeds do become leggy you can fix most seedlings when you transplant them by burying them almost up to the seed leaves. Be sure not to overwater if you do this.
Transfer The Seedlings
Once the seeds germinate and form their first true leaves, transfer them into individual pots that are slightly larger, about the size of a yogurt cup. This will allow for proper root development before they are transferred into the ground.
Hardening Off
Seedlings are ready to be transplanted into the ground when they have three or four true leaves, which are different than the first two leaves that form upon germination to produce and store food. Once these true leaves have formed, indoor seedlings will need a transition phase where they can get used to the outdoors in small doses.
Hardening them off means you simply place the containers outdoors for increasingly longer periods of time:
Look up the date of the last expected frost in your area and don’t attempt to harden off or transplant if temperatures are expected to fall below 45°F. Cool-weather plants like lettuce and kale will tolerate some cold, but warm-weather plants like tomatoes and melon will be much more sensitive.
Start by setting the seed containers in the shade for 2 to 3 hours a day.
After a few days, transition slowly to the sun for 2 to 3 hours a day and bring them indoors at night.
After a week or so, leave them out overnight.
Transplanting
Once seedlings have been hardened off they are ready for their permanent home in the outdoors.
Dig the planting hole slightly deeper and about twice as wide as the plant pot.
If you haven’t added compost or fertilizer to the soil yet, do it now.
Gently remove the dirt and seedling from its container and place it in its hole making sure its soil is level with the surrounding soil.
Do not bury the stem, except in the case of tomatoes, which enjoy being planted deeply.
Water the transplant and let it grow!
Thinning In-Ground Plants
Thinning your seedlings can seem wasteful, but it is necessary if you want any of them to succeed. As the seeds germinate, you will pull some of them out of the soil to make room for others to grow fully, ensuring there are enough nutrients for fewer healthy, mature plants to flourish. Do this in stages so that if an herbivore comes along, your fledgling garden isn’t wiped out. Your seed package will tell you how many inches of space to thin the seedlings to. If it says 8 inches apart, begin by thinning so that they are 2 inches apart, a week later thin so they are 4 inches apart, and so on until they are 8 inches apart.
Pro Tip: Save the seedlings that you pull from the ground and eat them for dinner. They are delicious in a salad and people pay top dollar at farmers markets for this delicacy. The best option in this case is to cut the seedlings at the base with a pair of scissors rather than pull them, so that you have dirt-free micro greens ready for the table. The remaining root will disintegrate on its own underneath the soil.
