Since garden centers soon will be flooded with flower, herb, and vegetable plants, it’s reasonable to ask why anyone would begin with seeds. In some cases, only the most devoted seed-starter would: Celery, for instance, needs to grow for several months before it’s ready to transplant outdoors. Also, buying seeds is a gardener’s only access to the thousands of varieties never sold as plants, and it’s a lot less expensive.
Sowing seeds indoors also lengthens the garden season – and moves it up. Americans have long been accused of being impatient, and no Americans are more in a rush than gardeners in the six weeks before spring. Yet getting a head start requires patience, too: The early bird may get the worm, but the second mouse gets the cheese, as one wit put it.
Seeds sown too early become leggy, weak, pot-bound plants long before it’s safe to move them to the garden. How do you know when to start seeds inside?
Determine your last frost/first freeze dates. Local gardeners and horticultural organizations are two fine resources for pinpointing these, or you can find them online. One of the easiest sites to use is www.plantmaps.com. Click on your state and then on the information you want (first frost, last frost, hardiness zone, etc.). The dates, based on data collected by the National Oceanic and Atmospheric Administration, are normal averages. They aren’t infallible, but are probably better than your neighbor’s memory.
Know your crop. Knowing when to sow seeds indoors requires knowing your crop, especially how much time the plants need to reach maturity and their cold hardiness. Any flower and vegetable seeds can be sown directly in the garden, but some take more days to bloom or produce fruit – called “days to maturity” – than a regional growing season can provide. (The growing season is the time between the last spring frost and the first fall freeze.) My season is 130 days, which isn’t enough time to ripen eggplants or see ageratum flower if I sowed their seeds outdoors.
Cold tolerance also affects sowing and transplanting times. Tomatoes and other “tender” plants that are injured or killed by near-freezing temperatures can’t go outdoors until a week after the frost-free date. “Hardy” plants, such as sweet peas, can be moved to the garden before the frost-free date. Lettuce is “half-hardy”: It can endure a brief, light frost and may be set out on or near the frost-free date.
Information about a plant’s characteristics and requirements is available in books, on seed packets, and in paper and online seed catalogs. You can also go online and search for a “seed starting chart” or type the name of a plant and “how to grow.”
Do the math. Or go online. Armed with frost/freeze dates, garden season length, and basic plant information, you can do the math yourself to determine when to plant seeds. Or you can check with my favorite seed-starting assistant: the interactive site at Johnny’s Selected Seeds (http://bit.ly/JohnnysSeedStart). It allows you to plug in your frost-free date and get the recommended date to start 96 flowers and vegetables indoors, along with the date to transplant outdoors. What could be easier?
Don’t scrimp on light. You can grow seedlings in almost any container with good drainage, but you can’t scrimp on light. Seedlings need at least 14 hours of bright light a day, which is more than they can get on most windowsills. To succeed, especially with seeds that need a long head start, you will need artificial lights. Or better still, get a greenhouse – then you can garden 12 months a year and never feel impatient.