Most seeds can be direct-sown into the garden when the time is right. But many folks like to get a jump on the season by growing vegetable starts. These are usually warm weather plants - tomatoes, eggplant, peppers, melons, cucumbers, etc. While you can grow them in a container with drainage - i.e. a Dixie cup with a whole hole in the bottom - most folks use seed trays and cell packs.
There are two trays, one with performations in the bottom and one without - you’ll want one of each. Cell packs are sheets of small cells that nestle snugly inside the seed trays. You’ll want one sheet of cells for each tray you intend to plant.
Clear plastic covers are also a good idea. You’ll need at least one, which can be rotated to other trays as the seedlings sprout.
For most seeds you don’t need starting mix - any good quality potting soil will work as well.
Put your unperforated tray on the bottom, insert the performated tray into it, followed by the cell pack. Dump an appropriate amount of potting soil into the center of the cell packs and spread it equally into the cells. Use your thumb to lightly tamp down the soil in each cell.
Put two seeds in each cell, cover with additional potting soil (1/4″ for tomatoes, eggplants, peppers, 1/2 inch for melons and cucumbers) and firm the soil lightly.
Lift the perforated tray and cell pack together out of the bottom tray. Fill that tray with an inch of warm water and float the perforated tray with the cell pack on it. Watering from the bottom up will give you even watering and minimize seed displacement, something that can happen when you top-water.
When the cells are dark and evenly moist, put the perforated tray with the cell pack over the sink to drain, dump the excess water out of the bottom tray and then place them back in the bottom tray. Snap on the plastic cover.
Put the assembled trays in a sunny, warm spot during the day and the warmest place possible at night. Most warm-weather seeds germinate best from 70 to 85 degrees, going slightly cooler once they develop leaves. If you’re growing different kinds of seeds in one flat, try to keep the estimated germination times as close as possible.
Seedling heat mats can be pricey, but are a good long-term investment, espeically for tomato and pepper starts. Another good, warm place to put your trays at night is on top of the your refrigerator, toward the back. Since the tray is higher in the room it will stay warmer and get additional warmth from the coils releasing heat in the back of fridge.
Once you’ve achieved 50% germination, take the plastic cover off for good. Keep the first seed to germinate in each cell and pluck out the other.
If your seedlings are tall and pale they aren’t getting enough light. Use a flourescent light to boost light levels and length of day (see below).
If they rot at the base - called “damping off” - they’re too wet and too cold. Toss the contents, sterilize your fresh potting soil by putting it into a 250-degree oven for an hour and start again.
Seedlings that seem spindly can be toughened up by putting them in the path of an oscilliating table fan set on low. The movement of the air will make them more robust, but also more likely to dry out.
Keep the cell packs evenly moist. With the cover on, they won’t need much water.
You can use fluorescent light to start your seeds or extend the length of the growing day. If hung by a fine chain, they can be precisely raised and kept 2″ to 4″ above your seedlings. You don’t have to use more expensive daylight spectrum bulbs. For most purposes a regular white bulb works just fine. Sow your seeds 6 to 8 weeks before you intend to plant them. which in our case will be around Memorial Day.
