Reap What You Sow
28 Mar 2012
Get a jump on your vegetable garden this spring by sowing seeds. Here’s a primer to you get started.
By Carol O’Meara Photos by Weinrauchphotography.com
Last year’s patch of lettuce, tomatoes and peppers proved so tasty, you’re already dreaming about this summer’s sweet, crunchy produce. But why dream when you can plan? Spring is the time to sow vegetable seeds, so start perusing seed packets now to have your ducks—or zucchini—in a row when planting time comes.
As opposed to starter plants, seeds give you many more options in the types of produce you can grow—everything from hard-to-find veggies to the more tasty heirlooms and unusual varieties. “The thing about starting your own seeds is you can choose from a bigger selection than buying seedlings at the store. Anyone can do it, and it’s a great project for kids,” says Dr. Steve Newman, Greenhouse Crops Specialist for Colorado State University Extension. “The only con is you always plant too much, and my wife won’t let me throw seedlings away.”
To get started, choose an area that can hold seed trays for six weeks or longer in a space that remains at 68˚ to 70˚ F, and out of drafts and traffic. (If you use heating mats and humidity tents—discussed below—your space can be 60˚ F or above and the seedlings will be fine.) Seeds need watering, with the possibility of spills, so placing seed trays over expensive carpet or wood floors isn’t optimal, unless you lay plastic beneath them.
Different planting media and containers are available, including open flats, plastic trays with 1-inch-square cells, Jiffy Peat pots and Jiffy Peat Pellets, which is peat moss in mesh netting that swells with the addition of water and transplants directly to a pot. Nearly any small container can hold seeds, even egg cartons, but most homemade containers will need drainage holes poked into the bottom.
Choose seed trays that suit your style, or clean and sterilize those you already have by dipping them in a solution of 10-percent bleach in water. Be sure to rinse the trays two or three times before using them, as bleach is lethal to plants. Using recycled containers is fine, but when it comes to soil, don’t scrimp. “Use clean, high-quality soilless mixes; you get what you pay for with seed-starting soil,” Newman says.
Soilless mixes provide good distribution of moisture and air for roots, as opposed to garden soil, which is too compacted for tender seedlings. The ideal medium for starting seeds is a lightweight, soilless mix of peat, vermiculite or perlite, and compost. Using a sterile mix avoids disease problems like damping off, caused by a fungus that attacks tender stems at the soil line, and other threats.
“The important thing is good drainage, so set the tray on another tray that’s filled with pebbles. Line the lower tray with Saran Wrap to keep it from leaking onto the floor,” Newman advises. A major threat to seedlings is drying out, so monitor seed trays closely.
Use plant labels to keep track of your varieties, and transfer the labels when you transplant the seedlings to larger pots, so you’ll know which seedling is which.
A humidity tent—a plastic covering that holds in moisture—assists seed germination. Bread bags are ideal tents, because they breathe; shrink-wrap is a no-no, because it doesn’t. Milk jugs with the bottoms cut off also make good humidity tents. Plastic seedling trays usually come with a lid to hold in moisture. Heating mats, available at nurseries and hardware stores, also speed up germination by warming the soil.
Seedlings need plenty of sunshine, but if you don’t have a sunny southern window to put them in, you’ll need lights. “This is where things can be simple or complex,” Newman says. “I start my seedlings under a fluorescent shop light with one cool-white and one warm-white bulb. You can get them at home-improvement stores for $30 to $40.” Newman prefers combination fluorescents to grow lights. “They provide the spectrum of lights plants need to thrive,” he says.
As seedlings sprout, crack the humidity tent to allow for better air circulation and immediately place the seed trays under lights so the plants don’t stretch and become leggy. Seedlings should be stocky; if yours start reaching, lower the lights closer to the plants.
Hang lights directly over seed trays on cords or chains for easy rais-ing or lowering. Always position lights 3 to 4 inches above the plants, and give plants 14 to 16 hours of light daily.
Planning Ahead
How far in advance of planting should you start seeds? “Most everything germinates in 14 days,” Newman notes, and then the seedlings need time to grow leaves, be transplanted and harden off before being planted in the garden—a process that usually takes six weeks in all. Read the seed packet to learn the optimal time for starting that particular plant from seed. The first leaves to appear are the cotyledons, which provide stored food to the seedling for a short period of time. Wait until the plants sport a few sets of true leaves, then transplant them into a next-size larger pot filled with sterile potting soil. Carefully lift them by the leaves, not the tender stem. “Pick them up by the ears, and use a plant stake to gently lift up the roots as you do so,” Newman says. “Otherwise, stems get crushed, which pinches the vascular system and kills the seedling.” If you use Jiffy Peat Pellets, there’s no need to lift the seedling from the soil to transplant it; simply plant the pellet in a larger pot with soil (some gardeners remove the mesh netting first before transplanting the seedling, so the roots can more easily expand into the soil). Seeds have plenty of nutrients, and most potting soils have a little fertilizer in them, so Newman says to hold off fertilizing transplants. When you do start fertilizing, do so at half strength. Your seedlings will be ready to plant outside after hardening off (see “How to Harden Off Seedlings” below). When the weather warms and is frost-free, tuck your seedlings gently into the garden. Then, when the harvest begins, you can tell your friends you knew their meal when it was just a little sprout.What You Need to Sow Seeds
-Space for seed trays -Trays for holding seedlings -Seeds -Seed labels -Sterile seed-starting soilless mix (called medium) -Lights (a combination of cool and warm fluorescents, or grow lights) -Chains or cords to raise or lower the lights -Timer for the lights
Steps to Sow Seeds
1. First, pick a planting medium for your seeds like Jiffy Peat Pellets. 2. Putting the pellets in a lidded tray on top of a heat mat hastens germination. 3. Generously water the pellets, which swell with moisture, and drop one to three seeds in each pellet’s hole. 4. After planting the seeds, set the tray under fluorescent lights with one cool-white and one warm-white bulb. 5. The first leaves to appear are the cotyledons, which provide stored food to the seedling. 6. Wait until the plant sports two or three sets of true leaves to transplant it into the next-size larger container. 7. Add sterile potting soil to the bottom of the container, then transfer the Jiffy Peat Pellet into the container and fill with soil. When it’s time to plant, harden off seedlings before transplanting them into the ground.How to Plant Seeds
In a large bowl mix the potting medium with water until damp, but not soaked. If using Jiffy Pellets, soak the pellet in water until peat completely expands and the mesh fully opens. Fill trays, cells or pots with damp medium. Avoid packing the medium into cells; keep it light and fluffy. Use a pencil or toothpick to make a hole to the planting depth listed on the seed packet. Pushing aside medium, rather than pushing the medium down, place seeds in hole and smooth over medium.How to Harden Off Seedlings
When it’s time to plant, harden off seedlings first by gradually exposing them to outside temperatures, sun and wind. One week before planting seedlings in the garden, harden them off by taking them outside. Start slowly by placing the plants outside during the warm part of the day in a lightly shaded, sheltered location for one to two hours. Increase the length of time outdoors in a sheltered location for two to five hours the next day.
On day three, expose plants to direct morning sunlight and place them in shade during the afternoon. Increase sun exposure to plants over the remaining days until they can withstand normal sun exposure for that plant. During the last two days of hardening off, allow plants to remain outside overnight if nighttime temperatures are normal.
