Seed Shelf Life


GerminationSeed vitality or shelf life is an important concept. If you saved seed from last season or the season before or if you’ve been given seed and are not sure how long it’s been around, you might want to perform a seed vitality test a couple of weeks before you plan to sow.

Seeds more than a year or two old may not germinate well or at all, particularly if they have not been stored properly. Some seeds, even after a year of proper storage, may not produce the number of plants you expect or need.

To test your seed for germination, place two paper towels on top of each other and moisten them with warm water. Next place 10 or 20 seeds in the middle of the towels. Fold the towels over from the four corners to the center. Place the towels in a glass with about 1 inch of water in the bottom–enough to keep the towels moist without submerging the seeds. Cover the glass with clear plastic bag and set it in a warm place.

After the average number of days to germination, unwrap the towel and count the number of seeds that have germinated. If none have sprouted re-wrap the towel and replace it in the glass and wait several more days. If seeds have sprouted, count the number of sprouts and divide by the total number of seeds on the towel. That will give you a good estimate of the germination rate for that batch of seeds and the success you can expect when you sow in the garden.

Vegetable Average rate of germination at 1 year (%) Average years seed will germinate Number of seeds per ounce Average days to germination
Asparagus 90 3 1,000 14-21
Beans 90 3 90-100 6-15
Cabbage 85 4 5,000 10-14
Carrot 75 3 14,000 14-21
Cauliflower 75 4 14,000 10-14
Corn, Sweet 85 3 125 5-7
Cucumber 85 5 1,000 7-10
Eggplant 75 4 5,000 7-14
Lettuce 90 6 12,000-16,000 7-10
Muskmelon 85 5 1,200 6-10
Mustard 85 3 18,000 8-12
Okra 85 1 425 10-14
Onion 80 2 12,5000 7-14
Parsnip 85 1 600 21-27
Pea 90 3 50-150 7-10
Pepper 75 2 4,000 10
Pumpkin 90 4 100 7-10
Radish 90 4 5,000 4-6
Spinach 80 3 3,000 8-12
Tomato 85 3 6,000-7,500 5-7
Turnip 90 4 10,000 7-10
Watermelon 85 5 175-225 6-8

Complete seed germination details: everything you need this year now in THE KITCHEN GARDEN GROWERS’ GUIDE.

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

How To Grow Tips

How To Grow Tomatoes

How To Grow Peppers

How To Grow Broccoli

How To Grow Carrots

How To Grow Beans

How To Grow Corn

How To Grow Peas

How To Grow Lettuce

How To Grow Cucumbers

How To Grow Zucchini and Summer Squash

How To Grow Onions

How To Grow Potatoes

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