When To Start the Seeds

This year’s gigantic assortment of seeds has finally arrived, bringing with it the usual gigantic dose of buyer’s remorse. I had firmly decided against bulbing onions, for instance, having concluded that purchased plants  –  also available mail order, in convenient bunches of 50 to 75 –  do much better than the plants I start myself.

Yet somehow, mysteriously, here is a packet of heirloom Australian Brown storage onion seeds, roughly 700 incipient plants. Here also are 8 kinds of peas, most of them the kinds that require poles. We cut way back last year and they were sorely missed, but this does not explain where the hell I’m going to put them all. As usual, too many tomatoes, but on the other hand I’m not going to start any eggplants.

I had no intention of getting into cardoons again, either, but then there was this nice packet of Gobbo di Nizza in one of those racks (well, you have to at least look), and a facebook friend had just assured me they really could be delicious and before I knew it, two dozen little green sprouts, each capable of becomming a bush 4 feet tall and almost as wide.

I’ve given individual pots to only 6 of the strongest-looking, but even that modest number will be eating too much precious seed starting space by the time it’s time to start the tomatoes.

And thus we arrive at When Is the Right Time to Start the Seeds? The chart at the end of the post provides some guidance and many seed packets have suggestions too, but the truth is it all depends.

SOME THINGS SEED STARTING TIME DEPENDS ON

* First and foremost, LIGHT. Outdoor plants do not cope well with the restricted light of indoors. A greenhouse helps, obviously, and grow lights can be almost as good. But if all you have is a windowsill it’s best to start only a very few things and to do it only a few weeks before they can start spending at least some time outside.

Tomatoes, for instance, are typically started 8 to 10 weeks before the last frost, but windowsill seedlings will be stronger if started no more than 6 weeks in advance. They’ll be small, but they’ll catch up, and they’ll catch up more rapidly than they would if they’d been stressed by two more weeks of low light.

* How dependable is the weather? All timing for seeds started indoors is calculated on the basis of distance to last frost. You can use a calculator like this one from NOAA to get a probable last frost date, but “probable” is the best that predictions can do. In places where there’s enough frost to worry about in the first place, spring weather is often unsettled. Balmy days can be followed by cold ones so blustery it is below freezing if you count the wind chill; and sometimes it’s just plain below freezing – late cold snaps can never be completely counted out.

On top of that, most tender plants prefer genuine warmth, in the air and in the soil. Forty five degrees is far from freezing, but if you’re a tomato it’s also far from warm. Short version: even though I have a greenhouse that lets me start early, I count as though “last frost” will be ten days later than predicted. If warm weather comes promptly, the seedlings will be a little smaller than planned, but that’s better than having them too big. (Seedlings that outgrow their pots get root bound, which sets them way back. )

*What’s the weather like indoors? A tomato seed may germinate in anywhere from 5 days to 2 weeks, depending on the temperature of the soil. (75 – 80 is ideal, but anything over 60 or so will work, eventually). This obviously affects how much of the allotted time the seedling is actually growing.

* How crucial is it that the vegetable, fruit or flower get a big head start? Plants that must make good growth in cool weather (delphiniums) and plants that are ruled by day length (onions) must be about 12 weeks old when planted out in early spring, no matter how long the growing season may be. Plants that just need three or four months of warmth after they hit the garden (tomatoes, peppers, daturas) have a lot more leeway – at least in places where the first fall frost doesn’t come until mid October or later.

* Some favorite sources for seeds , with a brief excursion into heirlooms and hybrids

More on seeds and seed starting:

Is seed starting really essential?

Organic seeds, starting off on the right foot

A Seed-Starting Timetable

(slightly adapted from one provided by  Kitchen Garden Seeds)

Counting back from last frost:

Vegetables

Four Weeks: Winter Squash, Melons, Cucumbers, Nasturtiums

Six Weeks:  Fennel,  Shallots, Tomatillos, Basil, Echinacea  and St. John’s Wort.

Eight Weeks: Eggplant, Tomatoes, Chiles, Sweet and Bell Peppers, Chives, Sage, Stevia and Thyme.

Nine Weeks: Broccoli, Cabbage and Kohlrabi (transplant out four weeks before the last frost date).

Ten Weeks: Celery, Celeriac.

Eleven Weeks: Leeks and Cauliflower (transplant out four weeks before the last frost date).

Twelve Weeks: Artichokes, Cardoons and Brussels Sprouts.

Flowers

Five Weeks: Alyssum, Calendula, Marigold, Zinnia.

Six Weeks: Balsam, Cutting Ageratum, China Asters, Celosia, Cleome, Coleus, Catmint Nepeta, Echinacea, Euphorbia, Forget-Me-Nots, Dahlia, Nicotiana, Scabiosa, Snapdragons, Stock, Thunbergia.

Eight Weeks: Baby’s Breath, Black-Eyed Susans, Milkweed, Coreopsis, Gaillardia, Globe Amaranth, Helichrysum, Hibiscus, Hollyhock, Heuchera, Nigella, Phlox, Platycodon, Statice, Yarrow.

Ten Weeks: Dianthus, Digitalis, Lobelia, Heliotrope.

Twelve Weeks: Datura, Salvia, Verbena, Viola.