The Island Garden
here, you have about six to eight weeks until planting out time.
Around here, May 1 is usually the last frost date, but given the weather we've seen this week, it is hard to believe. You can start seeds anytime over the next few weeks. If you have a nice sunny window, you can start them right away, but if you don't have a warm sunny spot, wait for a week or two or your plants might get leggy.
You don't want to plant up all your seedlings right away. I suggest you start with eggplants and peppers this week, as they take awhile to germinate. Next week start tomatoes, onions, leeks, and celery or celeriac. Then pause for a couple weeks before starting brussel sprouts and cabbage. With about two weeks to go before planting out you can start lettuce and other greens. If you have a cold frame, you can start lettuce greens about two weeks earlier than you would to plant outdoors.
In old England the saying is to get your potatoes and peas in by St. Patrick's day, but in New England, you might wait another two or three weeks. I have found that many small animals are very hungry early in spring and putting peas out now is simply feeding them. Again, if you have a cold frame you could start a few early potatoes in a week or so. Provided you have seed potatoes, of course.
Here's how to go about starting seeds. First, make sure your seed-planting trays are clean and sterile. If they aren't, fill a tub with warm water, add a little bleach and scrub each tray. If your trays aren't clean, you can get damping off and mildew, which will kill off your seedlings. Fill each tray with moist, good-quality potting soil and pat it down gently. If you grab a handful of potting soil and squeeze hard, you should get just a drip or two of water from it. It should not be any wetter. Spread your seeds over the soil and mark where you have seeded. Spray the seeds with a little water from a garden spray bottle. Now cover the seeds with a little potting soil. I use vermilculite, as it is light and easy to spread. Use a spray bottle to dampen the potting soil or vermilculite and cover the entire potting tray with plastic wrap. The wrap keeps moisture over the seeds. If you don't want to cover with plastic wrap, you should spray the seed flat every day to prevent it drying out.
In three to five days the seeds will sprout. Wait until the majority of the seeds have sprouted and remove the plastic wrap. I place my seed flats under fluorescent lights - two flats will fit nicely under a 4-foot-long shop-light fixture. The lights are placed an inch or two above the seedlings, and they stay there until the seedlings grow almost to the light tubes. At that time, most seedlings have their first true leaves and should be potted.
To pot your seedlings, fill 3or 4-inch pots with potting soil and holding onto the seedling's leaves not the stem, gently move the plants into the larger pots. You'll have to raise your lights a little, but that shouldn't be a problem. As the plants grow, keep the lights about an inch off the topmost leaves. You will need to harden off your seedlings before you plant them out, but we'll get into that in a month or so.