GARDENING : There’s Usually Plenty of Life Left in Old Seeds

Flower and vegetable seeds left over from a previous year are often still good.

In general, the fresher the seeds, the better the germination. But home gardeners are not likely to notice much difference when seed packets from a previous year are stored with a little care and the packet’s planting instructions are followed.

They probably will need to thin excess seedlings as always.

Onion, sweet corn, parsley, strawflower and candytuft are among those with the shortest shelf-life.

But vegetable seeds that normally carry over for three to five years include tomato, pea, bean, lettuce, beet, cabbage, cauliflower, radish, carrot, cucumber, watermelon, squash, spinach and eggplant.

So do flower seeds such as marigold, zinnia, pansy, petunia, verbena, cosmos, nasturtium, dianthus, stock, sweet pea and alyssum.

A few seeds on a moist paper towel provide a simple viability test. Fold them inside and keep the towel moist for 5 to 10 days at room temperature. If some seeds begin to develop roots, the remaining seeds in the packet are usable. Let the proportion of test germination determine whether to sow the remaining seeds at a heavier rate than the seed package calls for.

If none germinate, buy fresh seeds.

Of course, even if the seeds are viable, germination, as always, will not take place after planting unless moisture is consistent, planting depth is correct and a specific temperature range is met. The seed packet will give such guidelines.

While the moisture rate of seeds varies by species, commercial seed producers will have dried their fresh seeds to the correct moisture content before sale.

So the trick with excess seed is to keep it dry. A glass jar with a top makes an excellent moisture-resistant container. Often a cool, dry, dark room will be enough. Be sure to keep the seeds in the original packet so you will know what they are, their age and the recommended planting instructions.

Saving seeds from your own plants is worthwhile only if the plants were open pollinated; that is, non-hybrid. If the seed packet says the seeds are F1 or F2, forget it. While such seeds may germinate, the plants most likely will be inferior.

Open pollination means the seed was produced by natural processes. Gardeners for thousands of years have collected seeds from their most desirable plants for the next crop.

Such seeds sometimes are referred to as heirloom seeds, because they are handed down from generation to generation.

There are many arguments involving hybrids and heirlooms, such as the need to maintain genetic diversity or better flavor against the need of customers for easy-to-ship flowers and vegetables.

To save seeds of an exceptional vegetable or flower, be sure to dry them properly.

A simple method is to spread harvested seed on paper towels in an airy place. Moist clumps need to be broken up from time to time. A week of this treatment usually is sufficient.

A good precaution: When you think the seeds are dry, give them another day before storing. Practice and observation over the years will produce the best results in selection, storage and cultivation.