This article was co-authored by Andrew Carberry, MPH. Andrew Carberry has been working in food systems since 2008. He has a Masters in Public Health Nutrition and Public Health Planning and Administration from the University of Tennessee-Knoxville.
There are 9 references cited in this article, which can be found at the bottom of the page.
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Planting seeds in pots can be a great way to start a houseplant or indoor garden, or otherwise start seeds that you may later transplant into your garden. Starting seeds in pots does not need to be difficult, but it does require some planning and attention to ensure successful propagation of your new plant. Be sure to start the seeds carefully in a soil matrix meant for seedlings, and keep your new plants in sunny areas with proper exposure to heat and water.
While the principles of how to plant seeds in this article can apply to any kind of seed, I’m going to be focusing on starting seeds for edible plants.
When it comes to growing your own food, starting your plants from seeds can be very cost-effective. Seeds are much less expensive than baby plants (a.k.a. seedlings).
Figuring Out Which Seeds to Start
In the photo above you’ll see that my mom and I used empty plastic trays for this batch. Both trays are from the grocery store: the big clear one had croissants in it, and the three small ones had mushrooms in them. It was a perfect little set up though!
Radishes, carrots and peas love cool weather, so they’re usually the first plants to be sown outdoors for the spring growing season.
The process of dragging every plant outside and back in again was tiresome. I did eventually start corralling the smaller containers into large baskets and trays so I could move more plants at a time, but it was still not fun.
4. Water wisely.
Always use room-temperature water. Let chlorinated water sit overnight so chlorine can dissipate or use distilled water. Avoid using softened water. It’s important to keep soil consistently moist, but avoid overwatering, which promotes diseases, that can kill seedlings. Try not to splash water on leaves. An easy way to avoid this – as well as overwatering – is to dip base of your containers in water and allow the soil to absorb moisture from the bottom until moist. Some seed-starting kits supply a wicking mat that conducts water from a reservoir to dry soil. This may be the most goof-proof method of watering seedlings but you still have to be careful that the soil doesn’t stay too wet. Whatever you do, don’t miss a watering and let seeds or seedlings dry out. It’s a death sentence.
8. Give seedlings enough light.
Not enough light leads to leggy, tall seedlings that will struggle once transplanted outdoors. In mild winter areas, you can grow stocky seedlings in a bright south-facing window. Farther north, even a south-facing window may not provide enough light, especially in the middle of winter. Ideally, seedlings need 14-16 hours of direct light per day for healthiest growth. If seedlings begin bending toward the window, that’s a sure sign they are not getting enough light. Simply turning the pots won’t be enough – you may need to supply artificial lighting. Nurseries and mail order seed catalogs can provide lighting kits. Follow instructions carefully.
Start feeding your seedlings after they develop their second set of true leaves, applying a half-strength liquid fertilizer weekly. Apply it gently so seedlings are not dislodged from the soil. After four weeks, apply full-strength liquid fertilizer every other week until transplanting.
6. Keep soil warm.
Seeds need warm soil to germinate. They germinate slower, or not at all, in soils that are too cool. Most seeds will germinate at around 78°F. Waterproof heating mats, designed specifically for germinating seeds, keep soil at a constant temperature. You can buy them in most nurseries and garden centers. Or, you can place seed trays on top of a refrigerator or other warm appliance until seeds sprout. After germination, air temperature should be slightly below 70°F. Seedlings can withstand air temperature as low as 50°F as long as soil temperature remains 65-70°F.
Maybe you want grow plants from seeds to save money. It’s definitely cheaper than buying transplants. It will also be easier to find seeds of varieties not typically available for sale as transplants. Whatever the reason, starting plants from seeds is probably not a hard as you think. And growing plants all the way from seed to maturity is one of gardening’s most rewarding endeavors.
3. Plant at the proper depth.
You’ll find the proper planting depth on the seed packet. The general rule of thumb is to cover seeds with soil equal to three times their thickness – but be sure to read the seed packet planting instructions carefully. Some seeds, including certain lettuces and snapdragons, need light to germinate and should rest on the soil surface but still be in good contact with moist soil. Gentle tamping after sowing will help. After planting your seeds, use a spray bottle to wet the soil again.
Here are the basics in 10 steps.