Growing your own vegetable transplants

Story by Katharine Musso

Starting seed indoors is a favorite ritual of many home gardeners. It’s a commitment to a new growing season and an antidote to the weariness that accompanies a fading season. That being said, it’s not uncommon to get a little carried away. If all of your windowsills are filled with trays and your sunny kitchen and dining room tables are out of commission for their intended purposes, perhaps you should be more judicious this year. 

This exercise in patience is a good way to resist the temptation to plant the garden when frost is still a real threat.

Start seeds indoors only if they, and your garden, will benefit from the extra help. Direct sow the others at the appropriate time. Some plants, such as carrots and beets, resent any disturbance to their roots and should not be transplanted. Some seeds are easy self-starters, such as peas. Seeds that require time and warmth are the best candidates to start indoors. Tomatoes, basil, eggplants, leeks, and peppers appreciate being started inside, as do biennials such as parsley and artichokes. Here in Zone 8a, I start transplants in late February to set out at the beginning of April and start all over again in late June to set out at the beginning of August.

Seedlings will only succeed in a well-draining seed-starting mix. You can buy a commercial mix or make your own. What you cannot do is scoop up soil from your backyard with hopes of growing anything better than weeds and mold. Homemade mixes typically include one-third each of sand, vermiculite, and pasteurized soil or manure (ew! I cannot do it to my oven, but two hours at 250 F does the trick and pasteurizes soil). I use Jiffy-7 pellets, which are compressed peat moss disks in netting that expand in water. Whatever you use, make sure to protect the surface of your seed-starting trays from inevitable condensation and spills. And give your grandmother’s antique walnut table a pass altogether.

There are many seed-starting mixes on the market; just make sure the medium is sterile and well-draining. Photo by Katharine Musso.

Whatever medium you choose, it should be thoroughly moistened before planting any seeds. This allows you to place the seed at the correct depth. Check the seed packet for instructions, but pepper and tomato seeds are typically planted ¼ inch deep. 

Keep the mix moist, but not wet, for the first few days. Many seed kits come with clear plastic domes for this purpose. Be careful, however, and don’t overdo it; that would just encourage the development of mold or fungi. If excess condensation develops on the clear lid, remove it and let the mixture dry for 12-24 hours before replacing.

Starting artichokes can be tricky, making them good candidates for transplanting. Photo by Katharine Musso.

Before discussing the niceties of enhanced lighting and heating, let me acknowledge that many successful gardeners do nothing more than place seed starts in a sunny windowsill and water them only when they happen to think about it. That being said – tomatoes, eggplants, and peppers appreciate the gentle bottom heat of an electric propagation mat. I do not recommend anything along the lines of heating pads or electric blankets. Even if you manage to somehow not fry your seedlings, you just might manage to burn down your house. If you have access to shop lamps or a plant stand with fluorescent bulbs, set the seedlings a few inches from the bulbs. Raise the bulbs in 1-inch increments once the seedlings emerge and are growing. There’s no need for fancy full-spectrum bulbs because seedlings don’t need it; those benefit flowering and fruit setting on mature plants. Make sure to turn off the bulbs at least eight out of every 24 hours.

If your seedlings take off like gangbusters, you may need to pot them up before planting outdoors. If you have roots growing more than 1 inch outside their medium or it is clear that the seedlings’ roots are becoming hopelessly intertwined, move individual seedlings to 2-4-inch pots. I use biodegradable seed block or peat pots, but simple newspaper blocks work just as well. Because peat absorbs water in competition with seedlings, I break apart the pots or blocks before planting outdoors so the seedlings’ roots are not constricted by a peat barrier.

Transplants will thrive when they’ve received extra care and attention from the beginning. Photo by Jill Wellington.

You must properly harden off your seedlings – otherwise the time and effort you’ve invested in this endeavor will have been for nothing. We typically think of hardening off as acclimating the young plants to colder nighttime temperatures, but it is just important that plants be introduced to heat, direct sunlight, and wind. Allow up to two weeks for tender plants to acclimate to outdoor conditions. Start with just a few hours in a sheltered location that receives only indirect sunlight. Gradually increase the length of time a tray or pots spends outdoors and never place them outside if there is a possibility of frost. This exercise in patience is a good way to resist the temptation to plant the garden when frost is still a real threat.

When the time has finally arrived, check the planting area one last time. Water? Soil at 65-70 F or higher? Good drainage? Minimum of six hours of sunlight? Proper plant support? If the answers are “yes,” you’re ready to plant. Do this toward the end of the day so that the new transplants don’t spend their first few hours struggling in the sun. Ensure correct spacing for the plant type (typically a of minimum of 12 inches for pepper plants and 24 inches for tomato plants) and water in well. Then kick back and enjoy … until next week when you’ll start looking for signs of pest and disease. Just kidding. That’s for another article.

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