If you’re a beginning gardener or a gardener with limited space in patio planters, it’s highly practical to buy started seedlings at a local nursery or garden center. But if there’s a special variety of tomato or broccoli you’d like to try, or if you’re confident enough in your skills as a gardener to nurture a plant along from seed to transplant to garden harvest, now is the time to start your own seedlings indoors. Seeds of heat-loving plants like tomatoes, eggplants and peppers and cole crops like cabbage and broccoli, as well as herbs such as basil, oregano and thyme, can all be started now for transplanting into the garden after the last spring frost. In coastal Maine, with a frost-free growing season of around 150 days, this means somewhere around May 20.

While it’s helpful to have some seed-starting equipment like grow lights, heat mats, and cell flats and trays, you don’t have to buy into a fancy system. Old baking sheets lined with newspaper make fine trays, and cells for holding soil, made from plastic or biodegradable peat, coir or even cow poop, can be bought by the package. You can also use your own recycled and sterilized yogurt cups or pots made from recycled newspaper. My personal favorite are the mini-greenhouses I assemble from recycled plastic salad-greens containers. I poke holes in the bottom for drainage and use the lids as domes to keep in the humidity while seedlings are young.

The most important parts of the equation are the seeds and the starter mix. Get the best seeds you can find and use a soil mix specifically blended for young seedlings, not an all-purpose potting soil. In the very distant past I actually screened and mixed my own compost together with sphagnum peat moss and vermiculite to make my own starter mix, but there are many fine ones available. If you are interested in ultimate sustainability, go for ones made from coir, which is made from coconut husk fiber, as opposed to ones mixed with sphagnum peat, as peat bogs take hundreds of years to replenish themselves and coconut fiber is a byproduct of a largely renewable source. 

Ask anyone and they’ll tell you that a full-spectrum grow light is essential for healthy, bushy seedlings, but I confess I’ve raised many fine seedlings with just the light available from sunny windows. This works well if you don’t mind the seedlings taking over your dinner table and every windowsill, but if you think you’ll be starting your own seeds for many years, you could invest in a four-foot-wide, four-shelf adjustable wire-frame unit, which can hold a lot of flats, and over the top rig up a four-foot, two-bulb fluorescent fixture (so you can have full-spectrum light, by using one cool-white tube and one red-light tube) with S-hooks and chains for adjusting its height. Lights need to be three to four inches above the plants. As the seedlings grow, the light can be lifted link by link so it stays right above the plants. Install a lamp timer so the plants get 16 to 18 hours of light every day.

Before you even begin to plant your seeds, you can use a simple technique to pre-sprout them. This reduces the time of germination and also allows you to plant exactly the number of seedlings you want and no more. The seeds left in your packets can be saved for another year, traded with a gardening friend or, best yet, given to a would-be gardener as an incentive to start growing. To pre-sprout, you’ll need some small plastic or glass containers with lids. The ones used for cheese dips or hummus or glass containers for leftovers are perfect. Put a thoroughly moistened piece of paper towel in the bottom of the container, and sprinkle the desired number of seeds on the damp towel. Close the lid, and label it with the kind of seed inside. You’ll be amazed at how quickly some seed germinate. The fastest ones are those in the cabbage family — broccoli, kale, cauliflower, etc., and the slowest are usually pepper, eggplant and fennel, which need five to seven days, while tomatoes, beets, chard and squash send out a root in about three days.

As soon as you see roots coming out, plant them right away, before fine root hairs penetrate the paper towel. Use a toothpick, the tip of a vegetable peeler, or just your fingers to pick up the sprouts and plant them in moistened growing medium, covering them to about the depth of one or two seeds. Mist the pots daily and keep covered with plastic until little green leaves pop out. When the seedlings are one to two inches tall, fertilize them lightly with fish emulsion if you aren’t using a medium with long-lasting fertilizer included. Once seedlings reach three or four inches in height and sport two to four true leaves, they may be transplanted into larger pots for further growth or into the garden if you’ve used pots large enough to accommodate their full growth until it’s time to harden them off and transplant into the garden.