Seed catalogs, the biggest bargain in America today, are rolling in thick and fast, a reminder that spring isn't too far off. Green-thumbers can satisfy their planting urge by doing some armchair gardening while it's still cold outside. With pencil and pad, use catalog information to calculate your garden needs for the '83 season.
Most catalogs have attractive pictures, written descriptions of characteristics, and the number of days from seed planting to harvest. Many seed companies will also give complete cultural information under main headings (including insect control), number of seeds per ounce or per packet, and number of seeds needed to plant a certain area.
Even though the cost of seeds has risen over the years, the rate is not as great as for other items. They're still a big bargain when you compare them with the harvest.
Hybrid seeds are more expensive than open pollinated, and gardeners should study catalogs so they can decide if the extra cost for superior quality outweighs the lower cost of a variety that may not perform as well or taste as good.
The word hybrid comes from the Latin hybrida, meaning ''offspring of a tame sow and a wild boar.'' In the plant world, hybrids are crosses between selected parents of different varieties.
When two selected parents are crossed, by transferring pollen from the male to the female, the resulting seeds are called F1 hybrids (pronounced eff-one). The expense of hand pollination makes the seeds more costly. Nonhybrid seeds (called ''open pollinated'' ) cost less and in many cases give very favorable results.
When it comes to sweet peppers, eggplants, corn, and melons, we go for the hybrids. There are excellent hybrid tomatoes, but we still use some open-pollinated varieties along with them. We favor hybrids when it comes to impatiens, fibrous begonias, zinnias, petunias, snapdragons, and most of our marigolds.
If you saved seeds from your hybrid plants, don't expect to get superior results. Characteristics will vary, since they've been ''chance pollinated.''
Also, if you have seeds left over from last year, better test them for germination by spreading them on a moist paper towel in a pan. From 10 to 12 seeds is a good number. Carefully roll up the towel and keep it moist for about 10 days. Then unroll the towel and count the number of seeds that germinated. If you have 75 percent or more, don't hesitate to use them.
Use the chart to determine when you should sow seeds indoors for outdoor planting later. Sowing too early will give you tall, leggy, tough plants that may not do well after planting out.
Loose soil mix for seedbed: We recommend one of the so-called soilless mixes for seed starting. They are relatively sterile and loose enough so seeds can nestle in the crevices where tiny roots can easily take hold. Further, they don't harbor damping-off, the villain that makes young seeds flop over.
You can buy them already prepared at a garden store or you can buy the ingredients and mix your own. The soilless mixes contain milled sphagnum peat moss, perlite, and vermiculite. Two parts of the sphagnum and one each of perlite and fine vermiculite make a satisfactory seedbed.
Moisten it by putting the amount you want to use into a plastic bag and sprinkling thoroughly with water. After an hour or so, you can put it into your seed box, sow seeds on top, and set the box into a pan for subirrigation.
Keep water in the pan until the seeds are germinated. Cover the box with a glass or sheet of poly wrap (a bread wrapper is fine) until the seeds are germinated. Tiny seeds should not be covered with the medium, but larger seeds can have a dusting of the mix or some plain milled sphagnum over the top.
Germinating temperature is important. Most seeds need a temperature of 70 to 72 degrees F. night and day. See that night temperatures don't fall below. Also , be sure to add water to the pan which is at least 70 degrees or it will lower the temperature of the soil. An inexpensive heating cable will maintain a constant temperature. These and other heating devices are available at garden stores.
You can easily make a ''germinating chamber'' by laying the heating cable (follow directions) on the bottom of a wooden box, and placing the water pan with the seed box over the top of it.
Most tiny seeds need light for germination, so use clear plastic over the top and no soil cover. Seeds of pansy, portulaca, phlox, and calendula like darkness. These should be covered with a sprinkling of the medium, and a newspaper can be used to shut out light. Most large seeds are not light-fussy, so they should be covered with the medium to retain moisture around them. Salvia should be covered only lightly, as it needs light filtering through for good germination.
As soon as a good portion of seeds have sprouted, move them to a light, airy place. They now can stand a temperature of 60 to 65 degrees F. If the air is stagnant, use a tiny fan to move it around, but don't focus on the plants. The cooler air will produce stockier plants.
If you don't have a good light window, you may want to hang a fluorescent light over the seedlings. Two 40-watt tubes hung 4 or 5 inches above the plants will usually be sufficient to augment whatever natural light is available.
Transplant the seedlings as soon as they can be handled. If they start getting too tall before you set them out, pinch out the tips to make them branch and become more stocky.
Gardeners who have the germinating space may want to use plastic trays with cavities or cells in which two or three seeds can be sown. Then the transplanting chore is eliminated. Peat pots and pellets are still available, as are fiber and plastic boxes and pots of all shapes and sizes.
Time to start Plant Seed indoors (weeks) Ageratum (reg. varities) 12 to 16 Alyssum 12 to 16 Aster (annual) 4 to 6 Begonia (fibrous-rooted) 18 to 22 Browalia 12 to 16 Calendula (pot marigold) 4 to 6 Carnation (annual) 12 to 16 Celosia 4 to 6 Centaurea (cornflower) 8 to 10 Coleus 8 to 10 Cosmos4 to 6 Dahlia (from seed) 10 to 12 Dianthus (annual pinks) 12 to 16 Dusty miller (cineraria) 12 to 14 Geranium (seed) 18 to 20 Hollyhock (annual) 12 to 16 Impatiens (sultana) 9 to 12 Lobelia 15 to 22 Marigold (dwarf) 6 to 10 Marigold (tall) 6 to 10 Nicotiana 4 to 6 Pansy 22 to 26 Petunia 10 to 15 Phlox Drummondii (annual) 8 to 12 Portulaca (rose moss) 6 to 8 Rudbeckia (coneflower) 10 to 12 Salvia Splendens 8 to 10 Snapdragon 12 to 14 Sweet pea 8 to 10 Verbena 8 to 10 Zinnia 4 to 6 Cabbage 4 to 6 Celery 8 to 10 Eggplant 6 to 8 Melons 5 to 7 Pepper 6 to 8 Tomato 6 to 8