GARDENING : Hope Springs Eternal for Last Year’s Seeds

Can last year’s leftover flower and vegetable seeds still be used? Most can.

In general, the fresher the seed, the better the germination. But home gardeners who follow a leftover packet’s instructions probably will need to thin excess seedlings, as always.

Test viability by putting a pinch of seeds on a moist paper towel, folding the seeds inside and keeping the towel moist for five to 10 days at room temperature.

If some seeds begin to develop roots, the remainder are usable.

Let the proportion of germination determine whether to sow them at a heavier rate than the seed package recommends.

Seeds with the shortest shelf life are onion, sweet corn, parsley, strawflower and candytuft.

But tomato, pea, bean, lettuce, beet, cabbage, cauliflower, radish, carrot, cucumber, watermelon, squash, spinach and eggplant are fairly easy to store at home for three to five years.

Long storage also is possible for flower seeds such as marigold, zinnia, pansy, petunia, verbena and alyssum.

Remember, though, that even if the seeds are viable, germination will not take place after planting unless garden moisture is consistent, planting depth is correct and specific temperature ranges are met.

Read the seed packet for planting guidelines.

Saving seeds from your plants is worthwhile only if the plants are non-hybrids (open pollinated). Save your time if the original seed packet says the seeds are F1, F2 or hybrids. Such seeds may germinate, but the plants will be inferior to the originals.

Open pollination means the seed was produced by natural processes. Gardeners for thousands of years collected seeds from their most desirable plants for the next crop. Because such seeds are handed down from generation to generation, they often are referred to as heirloom seeds.

There is much debate over hybrids and heirlooms. Heirlooms maintain the desirable genetic diversity and usually taste better. Hybrids help meet demands for flawless, readily available, larger produce that ships easily to market. They are often bred to be more resistant to insects and diseases.

Where I garden, in the desert Southwest, gardeners must routinely carry over seed if they want to try a year’s new introductions. Most catalogues are aimed at the Snow Belt’s spring planters, and the desert’s best planting time is long gone when catalogues arrive.

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 keep leftover seeds dry. A glass jar with a tight top is a fine, moisture-resistant container. A cool, dry, dark room also is needed. Be sure to keep the seeds in the original packet so you will know what they are, their age and the recommended planting instructions.

If you want to save your seed, an excellent reference is “Seed to Seed” by Suzanne Ashworth. It is published by the nonprofit Seed Savers Exchange, Route 3, Box 239, Decorah, Iowa, a leader of the heirloom-seed movement.

While there are many technical details of seed saving, probably the most important rule is: Seed that is not dried properly will keep poorly and germinate poorly.

A simple method is spreading harvested seeds 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. But when you think the seeds are dry, give them another day before storing. Practice and observation is the best teacher.