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Sow Good: Supplies for Starting Seeds
by Peter Loewer
Amazed at the proliferation of electronic equipment aimed at absorbing valuable parts of your day? Wondering if you should invest in a do-it-yourself DNA test to make sure you are you? Shocked by the headlines alerting you to the dangers of genetically engineered seeds? Aren't we all.
With the ever-increasing emphasis on gadgets, you might expect new technology to be sweeping the seed industry. There have been a few changes in equipment over the past few years, but most of what's available to home gardeners is only a modification of traditional supplies. So throw complications to the winds, enter the low-tech world of starting plants from seed, and relax.
Containers
I know a rock-garden enthusiast who visits a local fast-food joint every morning with her husband and winds up each spring with some 700 Styrofoam coffee cups for starting seed. (Recently, blocks of expanded polystyrene have appeared on the market. They measure about 6x3x2 1/2 inches and have 18 holes that hold cylinders of compressed peat. They can be used again and again by simply replacing the peat cylinders.) But if coffee cups, yogurt containers, or plastic jugs aren't your idea of a successful container, look for any of the following—just remember that any container must have drainage holes.
The basic tools for starting plants from seed are rather low-tech: an assortment of pots and a sterile potting mix.
Speedling trays™
Popular commercial versions of my friend's polystyrene coffee cups, these are reusable celled trays with cells that taper toward the bottom so the seedling and its roots pop out with ease. Trays come in sizes from 338 cells to just 32 cells for large seeds. Prices range between $6 and $10, depending on the number of cells per tray. Replacement inserts are $3. (Heavy plastic trays with either 432 or 192 tapered cells cost about $8.)
Plastic pots and trays
There are all sorts and sizes of plastic containers—from 1 to 4 or more inches across—made for sowing seeds. You can choose small individual pots, open flats, flats that are divided into cells, or plugs (which make transplanting less stressful for the seedlings). Most small plastic pots cost only a few cents each; six-cell containers are usually sold in a sheet of 15 ($2), and the flat to hold them is another $1.50.
Many retailers now offer APS (Accelerated Propagation System) kits, which include a solid-bottom flat, a mesh-bottom flat, a capillary water mat, a cell or plug tray (up to 288 cells), and a clear plastic lid for about $12. All plastic containers can be used season after season, but remember to clean them after every use.
Peat pellets and containers
Peat pellets are made of compressed sphagnum peat, held together by a bit of plastic netting, which expands when wet. Most are about 1 1/2 inches in diameter and a little over 2 inches high when they expand. Pellets, which require no additional container, are perfect for planting just one or two seeds, but they retain water astonishingly well, so be careful when you use them. The manufacturers say it isn't necessary, but I remove the netting when I set each seedling in the garden ($10 for 50 pellets).
Peat pots are made from sphagnum peat moss and wool fiber. Available in various sizes, both round and square, they must be filled with a planting medium, but when it's time to transplant, plant and pot can go into the garden. Although plant roots can penetrate the pot walls, when I plant them out I always tear away most of the bottom and some of the sides, just to help the roots along. Fifty square 2-inch pots in a plastic holding tray cost about $7.
Fiber packs
These containers usually come as 11x21-inch trays (2 1/2 inches deep), divided into six 5x7-inch or ten 4x5-inch containers that can be separated. They're made of recycled cardboard, and when they wear out, you can add them to the compost pile. Cheap (six trays of 5x7-inch containers are $12) and popular.
Potmaker
Here's a cunning wood device (it looks like a pepper grinder) that turns strips of newspaper into 2 1/2-inch pots perfect for starting seeds and housing young transplants. No glue is needed—just roll paper strips into little paper pots that naturally decompose in the ground. A bargain at $13.
Soil blockers compress moistened potting mix into perfect blocks, ideal for seed-starting.
Soil blockers
Soil blockers come in three sizes: 1/2-, 2-, and 4-inch squares. Made in England from zinc-coated steel, these tools compress moistened potting mix into perfect little blocks. There are even pins available to make perfect openings in the soil blocks for the seeds. The 4-inch model is too large for a home gardener, and the smallest model too small. Pick the 2-inch blocker, $25 to $30. Anyone who has used one swears by it.
Growing Media
There is one caveat when dealing with seed-starting: Whatever medium you use, make sure it's sterile. That bugaboo called "damping-off," an old term for the fungi-caused destruction of seedlings just when the little stems emerge from the soil, is no laughing matter. The easiest and safest solution is to purchase a sterile seed-starting mix. There are dozens of products, all widely available and inexpensive—about $5 for a 9-quart bag—and organic mixes are available, if you prefer. The ingredients vary from one product to another, but most are both soilless and nutritionless mixes; they primarily contain sphagnum peat moss, perlite, and vermiculite in some combination.
If you'd rather, you can make your own soilless medium. Of the various combinations that I've tried over the years, my favorite seed-starting medium is equal parts milled sphagnum peat moss, perlite, vermiculite, and sand.
Sphagnum peat moss
Sphagnum peat moss consists of partially decayed mosses that come from bogs; it is highly acidic and has a fantastic ability to absorb water, up to 25 times its dry weight. For years I started seeds in peat alone, but this proved to be a liability because peat has no nutrition. All seedlings require fertilizer as soon as their true leaves appear. In order to save time and effort, I now plant my seeds in a soil mix but sprinkle a 1/2-inch layer of shredded peat moss on top of the mix to discourage damping-off.
Perlite
Perlite is made from volcanic rock that has been heated and crushed. It's used like sand, but it's too light to be used alone and provides no nutrition.
Vermiculite
Vermiculite is a lightweight material made from mica heated to 2000°F, which breaks it into very small particles. It retains moisture and doesn't pack down, but has no nutritive value.
Sharp sand
Sharp sand, or builder's sand, has larger grains than common sand—they're rough, or sharp, to the touch. Don't use ocean sand, which is usually too fine and contains salt.
Heating Devices
Seeds and cuttings sprout best when they have bottom heat. The usual recommended location—the top of the refrigerator—has obvious limitations, and there are two good alternatives. Far and away the easiest solution for providing warmth is a heating, or propagation, mat. It's a flat sheet of heavy rubber (sizes vary, but common measurements are 10x20, 20x20, and 28x20 inches) that produces even heat. You just set your tray of seedlings on top of the mat and plug it in. A 10x20-inch mat runs $30 to $35. (There are slightly more expensive setups that include a wire frame with the self-regulating mat; $80 to $95 for a 17x38-inch frame and mat.)
Waterproof heating cables are less expensive ($20 for 12 feet, $25 for 24 feet) but a bit more trouble. Most come with a built-in thermostat set for about 74°F. (You can buy an additional thermostat if you want to adjust the settings; $45.) The cables come in 6-, 12-, 14-, 36-, and 48-foot lengths. The recommendation is 4 feet of cable for each square foot of space. Cables are normally buried in the planting medium, or you can arrange the cable on a layer of masonite or other insulating material, cover it with a layer of sand, and place your trays and containers on top of the sand.
Lights
Unless you start seeds in a greenhouse or outdoors in a cold frame, you've got to have supplementary light; without it, seedlings become leggy in their search for light. What you purchase depends on how many seeds or cuttings you want to raise. Individual lights are fine for just one or two containers of seeds or cuttings. Clamp-on fixtures with black reflectors and full-spectrum fluorescent bulbs run $25 to $30; replacement bulbs are $8 to $10. More ambitious gardeners can pick up an inexpensive fixture at the local hardware store—the traditional hanging 24-inch "workshop" light—then fit it with a full-spectrum fluorescent tube, for about $10.
Light stands are just what the name suggests: metal stands of various sizes equipped with light fixtures. They are wonderfully convenient but don't come cheap, about $500 for a model 27 inches long, 12 inches wide, and 70 inches tall (with four shelves, four fixtures, and eight bulbs). A tabletop model with one fixture and bulb will cost $150 to $250. If you're serious about raising plants from seed, a light stand is worth thinking about.
Emerging seedlings need at least 16 hours of light a day, so whatever kinds or sizes of artificial lights you use, you'll want to have a timer to control them. Timers that offer several cycles per day run about $15.
Cold Frames
Homemade or prefabricated, a cold frame is a great place to sow seeds, especially if you install heater cables and turn it into a hotbed.
A cold frame is not just a place to harden off plants or to overwinter tender species. It's also a great place to sow seeds, especially if you install heater cables and turn it into a hotbed. A homemade cold frame made from four bales of hay and an old window works fine, but if you aren't handy in the woodworking department and want something more permanent and better looking, you're in luck.
Prefabricated cold frames will set you back about $125. That buys you a 2x4-foot (18 inches tall in back, 12 inches in front) redwood frame with an insulated polycarbonate light. For another $45 you get an automatic vent operator—heat powered—that will save you from running in and out several times a day. For big-league growers, there is a lightweight PVC-pipe cold frame—6x8 feet—fitted with translucent corrugated polyethylene glazing guaranteed to keep the soil 10 degrees warmer on sunny days. $185.
Extras
In addition to the standard equipment, it's always a good idea to have plenty of white plastic labels ($3 for fifty 5-inch tags) and waterproof pens ($4). Memories are short, and it's easy to forget exactly what seeds were planted in what container on what day. You'll also want a way to water gently—either get a fine rose for your watering can or buy a misting nozzle for your hose ($10).
Peter Loewer, who is also a movie reviewer, has written many books on gardening and natural history. His titles include The Moonflower (with Jean Loewer, 1998), an award-winning book for children. He gardens on one acre in western North Carolina, where he grows many of his plants from seed.
Photos: Alan & Linda Detrick, Neil Soderstrom, Jerry Pavia