Anyone who gardens over time accumulates a trove of leftover vegetable seed envelopes, half-full or half-empty, depending on your disposition. When we plant vegetables, most of us don’t throw away unused seed. After all, we are gardeners, and it’s not in our nature to squander.

So we wind up with the seed drawer or, in my case, the seed basket, although at one time I also had an enormous seed box, in which I arranged my crumpled seed envelopes alphabetically. My box period, during which my Virgo retentiveness was on full display, was the antithesis of an earlier storage system involving an assortment of crumpled paper sacks. The sack thing might best be described as seed chaos.

Just so you know, none of these storage methods is approved by horticultural experts. They want you to store leftover seed in a cool and dry place. They frequently suggest a jar in the refrigerator. The problem with this advice is that most home gardeners cannot create the moisture-free, climate-controlled conditions required for storing seeds in a refrigerator.

When I tried this early in my gardening career, I was unimpressed with the germination rates the following year. The results certainly weren’t worth the hassle.

If you leave your seeds to chance in unrefrigerated storage, you can expect to have fairly decent germination the following year, provided the seeds were kept in a reasonably dry place through the summer, fall and winter. So unless you run a humidifier in your house through the winter or you don’t air-condition during the summer, your germination rate probably will be reasonably good.

One thing to remember is that the germination rate varies for all vegetables, as does the seed life. For example, rosemary is notoriously difficult to germinate from seed, while cilantro and dill are not. Melon seeds are eager sprouters, even when they have overwintered outdoors in a compost pile. By contrast, parsnip seed is usually spent a few months after you buy it.

While there is no single standard for how seeds will behave, the rule of thumb is that the harder the seed covering, the longer the shelf life. Seeds for such vegetables as spinach, broccoli and okra can be expected to last five years, according to the Iowa State University horticultural Web site.

Other vegetables whose seed should remain viable for four or five years are beets, cabbage, cauliflower, cukes, lettuce, muskmelons, pumpkins, radishes, squash, tomatoes and watermelons. Peppers, corn and onions have the shortest seed life at two years or less, and beans, carrots and peas are in the three-year category.

Two approaches suggest themselves. As we are sorting through our leftover seeds this spring, prudent gardeners might decide to compost all those seeds that have passed their theoretical expiration date. Why bother planting when the odds are that the seeds won’t germinate?

Another and equally prudent approach would be to go ahead and sow the aging seeds but mix them in with fresh seed. This would make sense for such vegetables as corn, carrots and lettuce, which we intentionally overseed and then thin.

The most practical approach, of course, is to stop buying so much seed. This is harder to do than it might seem. Seed companies have their own version of the “supersize it” problem, although some companies, such as Pinetree Garden Seeds (www.superseeds.com) and Territorial Seed Co. (www.territorialseed.com), offer envelope sizes specifically designed for small-scale home gardeners who don’t want leftovers.