Steps to Start Seedlings Indoors

Although many first-time gardeners choose to purchase transplants and direct sow seeds, some want to start seeds indoors. With an understanding of the basics and following the outlined steps, you can give your plants a healthy start.
Most seeds are started indoors 4 to 6 weeks prior to the transplanting date; however, some seeds require more time (e.g., peppers) and some less (e.g., squash and other cucurbits).

Plant two seeds per cell. If both germinate, snip the weaker seedling at soil level after the second set of leaves appears. (The first leaves to appear are cotyledons, not actual leaves. They will eventually die off after several sets of “true” leaves form.)
A healthy seedling will be compact and stocky. If you notice a seedling growing tall and turning toward the light, the light levels aren’t sufficient. If you’re using a grow light, bring the seedlings closer to the light. If the seedling suddenly wilts and dies, it likely had a condition called “damping off,” which is a fungal disease present in the soil. Start seeds with a bagged seed-starting mix, using new or sterile containers, to avoid this problem.
When the seedlings grow more than twice the height of the container, prepare to either transfer the plant to a larger container or plant it in the garden if possible. Plants will suffer if they remain for too long in a container that is too small, and if they survive until transplanting, they’ll have a harder time adjusting.

To start growing seeds:

1. Gather seed packets, seed-starting supplies (see here ), large bowl, serving spoon, watering can or large cup, spray bottle, and plastic wrap.
2. Pour your seed-starting mix into the large bowl, leaving about 1 cup of mix in the bag. Add enough water to the bowl to moisten the seed-starting mixture. Mix well.
3. Scoop moistened seed-starting mix into a seed-starting tray or container. Fill to within ¼ inch of the top. Place the tray or container inside a second tray (seed-starting kits come with this; otherwise, use a rimmed baking sheet).
4. Place two seeds per cell on top of the mix. Tamp down slightly, and except for the largest seeds (e.g., peas or squash), do not bury the seed.
5. Label the cells or groups of cells with the type and variety of seed.
6. Sprinkle the reserved 1 cup of seed-starting mix on top of the seed to barely cover it.
7. Using a spray bottle, mist the new seed-starting mix until thoroughly moistened.
8. If your seed-starting tray has a dome, cover the tray with it. If there is no dome, spread a layer of plastic wrap on top of the containers. Poke a few holes in the top with a toothpick.
9. Check on your seeds every couple of days, misting again if the top of the soil begins to dry out.
10. With a dome or plastic wrap in place, this may not be necessary for several days, if at all.
11. When the first seedlings appear, remove the dome or plastic wrap and immediately place the tray just a few inches under a grow light. Keep the grow light on for 16 hours per day. Mist your seedlings daily.
12. When the second set of leaves appears (the first “true” leaves), begin watering the trays from the bottom, filling the tray with ¼ inch of water. (Watering young seedlings from the top can damage their stems.)
13. As the seedlings grow, move the grow light up, keeping the tops of the plants 4 to 6 inches from the light. Keep the soil moist but not waterlogged. If you water from the bottom and the soil hasn’t taken up all the water within an hour, remove excess water with a turkey baster, or pour it off carefully.

Using Recycled Materials to Start Seeds
Although you can purchase seed-starting trays and seed-starting kits, you can also repurpose existing materials. Here are some great options.
Plant pots. If you planted flowers or vegetables last year and kept the containers, use them. Just be sure to sterilize them with a 10 percent bleach mixture.
Newspaper pots. Wrap newspaper strips around soup cans and tape the strips together to secure them. Then, remove the can and you have a seed-starting pot that you can transplant directly into the ground when ready.
Plastic cups or yogurt containers. With holes poked in the bottom, plastic cups are an excellent option.
Toilet paper rolls. Cut the cardboard rolls in half and fold the bottom under to create a stable base. Toilet paper rolls can transplant directly into the garden, but because they don’t break down into the soil quickly, you should unfold the bottom before transplanting them.
Although cute, eggshells or egg cartons are not good options because the root systems of most plants require more space than eggshells or cartons allow.

References

Bradley, Fern Marshall, Barbara W. Ellis, and Deborah Martin. The Organic Gardener’s Handbook of Natural Pest and Disease Control. New York: Rodale, Inc., 2009.

Bradley, Fern Marshall, Barbara W. Ellis, and Ellen Phillips. Rodale’s Ultimate Encyclopedia of Organic Gardening. New York: Rodale, Inc., 2009.

Bradley, Fern Marshall, and Jane Courtier. Vegetable Gardening. White Plains, NY: Toucan Books, 2006.

Cool Springs Press. Gardening Complete. Minneapolis: Cool Springs Press, 2018.

Damrosch, Barbara. The Garden Primer . New York: Workman Publishing, Inc., 2008.

Harrington, J. F. “Soil Temperature Conditions for Vegetable Seed Germination.” University of California at Davis. Accessed October 18, 2019.

https://extension.oregonstate.edu/sites/default/files/documents/12281/soiltemps.pdf .

McCrate, Colin, and Brad Halm. High-Yield Vegetable Gardening . North Adams, MA: Storey Publishing, 2015.

Reich, Lee. Weedless Gardening . New York: Workman Publishing Co., Inc., 2001.

Southern Exposure Seed Exchange (blog). “The Major Plant Families in a Vegetable Garden.” Accessed October 22, 2019. http://www.southernexposure.com/the-major-plant-families-in-a-vegetable-garden-ezp-190.html .