UNL Extension – helping you turn knowledge into "know how"
Good Seeds? Bad Seeds?
submitted by Don Janssen, UNL Extension Educator
You're trying to put your seed and plant order together, and you're wondering if the seeds leftover from last year's garden are still good. You don't want to buy more if these are OK, but you don't want to be disappointed if you rely on them and they're not. How the seeds were stored may be the clue you're looking for.
If seeds have been stored in moisture- and vapor-proof containers in a cool area, most seeds that were new last year will probably germinate just fine. Seeds such as tomato, carrot, pumpkin, kale, cucumber, Brussels sprout and cabbage will still be viable for two or even three years if they're stored properly.
On the other hand, if seed packets were merely stuck in a box and set on a shelf in the garage or the mud room, where they were exposed to last summer's tropical heat and humidity, even long-lived seeds might not germinate well.
So what should you do? Gamble on the old seeds or buy new? How about conducting a home germination test on the leftover seed.
Start by dampening as many paper towels as you have seed packets you want to test. Take 10 seeds from each packet and roll them in a moist paper towel, wrap rubber bands or twist ties around the towels to keep the seeds from falling out, and place each towel in a labeled plastic bag in a warm spot (75 to 90 degrees Fahrenheit). The top of the refrigerator is usually a good place, especially if there are cupboards above it to hold in the heat it generates.
Under warm, moist conditions, most seeds that are going to germinate will do it in a week. So, after a week, count the number of seeds in each paper towel that have sprouted and multiply by 10 to get a germination percentage for each lot.
Any seed with a germination rate of 50 percent or below should probably be replaced. Higher rates suggest that the seed will probably be OK for this year, though you may want to plant it a little thicker than usual, just in case the germination rate outdoors is lower.
For a good harvest from your major crops, it would probably be wise to plant a mixture of new and old seed. If you know you need a certain quantity of snap beans or sweet corn or butternut squash or pickling cucumbers, buying a little extra fresh seed is pretty cheap insurance that the produce will be there when you're ready to preserve it.
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office