Easy as One, Two, Seed! Cool-Weather Vegetable Sowing Indoors
Updated: Mar 31, 2022
It’s February, and Central Indiana has dug out from the first and probably only significant snowfall this winter. Gardeners are going crazy with cabin fever, longing for spring, with their gardens still in the grip of winter. Although it’s too early to plant outdoors, it’s the perfect time to start some indoor seed sowing of cold-tolerant vegetables to have transplants ready by April. These include cabbages, broccoli, lettuces, and onions, all of which are very easy to grow. Other popular warm-weather vegetables such as tomatoes and peppers should be sown in mid-March to be ready to transplant after Mother’s Day. In my last blog post, I reviewed the important considerations of light, warmth, and air circulation for successful early seed sowing for both cool and warm-season vegetables, so please keep those in mind.
Onions are probably the easiest vegetable to grow from seed to get both green scallions and storage onions. I’ve learned that I can plant an entire package of onion seed in a 6” pot or any shallow container like one of those plastic clam-shell salad containers (just be sure to poke holes on the bottom for drainage) to get growth as dense as grass. This saves spending money are cell trays and planting mix. Surprisingly, the crowded seedlings do just fine until ready to transplant into the garden. In March, as soon as the soil is workable, I pull the whole mass of onions out of the pot and use a hose to carefully loosen the scallions. Planted only about an inch apart, they provide green onions well into summer. (Storage onions are spaced about 4” apart to allow for the bulb development.) All onions withstand late spring frosts, even snow, very well.
Other than onions, except for perhaps leaf lettuces, sprouts of cool-weather vegetables (and flowers) should be drastically thinned to just one per cell, peat pot, or whatever small container being used. Remember that each little seedling will grow into a single, good-sized vegetable. Left crowded, seedlings will be stunted and weak, resulting in disappointing plants.
Last year, I planted my cabbage and lettuce seeds in March, but the transplants were still small when I set them out in the garden in early April, so this year I’m sowing them now, in mid-February. They should be an impressive size in six weeks. I fertilize all of my transplants weekly with diluted liquid fertilizer to boost growth. Fish emulsion stinks, but is a great organic fertilizer!
NOTE: It’s very important to acclimate cool-weather seedlings to outdoor conditions before transplanting to the garden. I start setting them outside on sunny spring days whenever temperatures are in the 40s, but bring them indoors at night. This toughens them up, lessening transplant shock.
With anticipated high store prices of vegetables this year, it’s both economical and fun to grow your own from seed. If you’ve never tried spring indoor seed sowing before, I encourage you to give it a go.