Seed Starting: When to Start What?

About this time of year, the itch to start seed starting hits. Those late winter snowstorms send gardeners into their basements to find their lights and flats and double check their stash of seeds to make sure they have all they want. Some gardeners can’t wait even this long, and for them there is winter sowing.

Tomato seedlings thrive under lights.

If you prefer to start seeds indoors, most annuals and vegetables should be started between early March and mid-April in Minnesota. The University of Minnesota Extension service has a fine post about seed starting and recommends that brassicas (cauliflower, broccoli and cabbage) as well as lettuces be started indoors in early to mid-March. (Onions and celery need an even earlier start.) The brassicas are cold-weather crops and generally can be put outdoors earlier and do well in cold frames or hoop houses. A long list of popular annuals, such as petunias, ageratum, coleus and snapdragons, can also be started from seed in early March.

In mid- to late March, plant your peppers and eggplants as well as marigolds, annual phlox, cleome and hollyhocks. These all need eight to 10 weeks indoors under lights before the last frost date.

Hold off until April before doing your seed starting for tomatoes. While some folks plant them earlier, the U recommends waiting. My experience is the seedlings are stronger if they are started later, though I’m sure with enough light and fertilizer you can grow very large plants indoors by giving them more time.

April is also a good time to do seed starting on annuals such as baby’s breath, morning glory, nasturtium, cosmos and zinnias. Some of these annuals can also be sown outdoors after the last frost date for a later bloom.

To learn more about seed starting, check out our articles here, here and here. Or, better yet, take a class from the experts! On March 6, MSHS is hosting a class on seed starting indoors taught by Tom McKusick, publisher of Northern Gardener magazine and a tomato enthusiast, and Marty Bergland, a frequent garden instructor in the Twin Cities.



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