G2090

Vegetable Garden Seed Storage and Germination Requirements

Leftover vegetable seeds can be used next year if stored properly. This publication covers how to select and store seed, and conduct germination tests.

Dale T. Lindgren, Extension Specialist
Sarah J. Browning, Extension Educator

Figure 1. Choose high-quality seed adapted to Nebraska’s growing conditions for your garden.
Figure 1. Choose high-quality seed adapted to Nebraska’s growing conditions for your garden.

A successful garden begins with selecting and using high quality seed of superior varieties adapted to Nebraska’s growing conditions (Figure 1). Start by purchasing seed from a reputable seed company. Save records of seed orders so you can contact the seed company if you have a complaint. Saving the seed orders is also useful for keeping track of the varieties you planted.

Storing Seed

Often seed is left over after planting and can be saved for next year’s garden, usually with little loss in germination. Seed stored for more than one year, however, will require additional care to ensure high germination for future use.

Storage temperature, relative humidity, and seed moisture are important factors when determining how long seed can be stored without loss of germination. Storage life also varies greatly with species (Table I). In general, longer seed storage life is obtained when seeds are kept dry and at low temperatures.

Table I. Seed weight and longevity for home garden vegetables.
Crop
Seeds per Ouncea
Seeds per Grama
Relative Longevity under Cool, Dry Condition (Years)ab
Asparagus
1,200
40
3
Bean, Lima
25-75
1-3
3
Bean, Snap
100-125
4
3
Beets
1,600
55
4
Broccoli
9,000
320
3
Brussels Sprouts
8,500
320
4
Cabbage
8,500
320
4
Carrot
23,000
820
3
Cauliflower
9,000
320
4
Celeriac
70,000
2,500
3
Celery
70,000
2,500
3
Chicory
26,000
900
4
Chinese Cabbage
18,000
650
3
Cucumber
1,100
40
5
Eggplant
6,000
200
4
Endive
26,000
900
5
Kale
9,000
320
4
Kohlrabi
9,000
320
3
Leek
11,000
400
6
Lettuce
25,000
900
5
Muskmelon
1,300
45
5
New Zealand Spinach
350
12
3
Okra
500
20
2
Onion
8,500
300
1
Parsley
18,500
660
1
Parsnip
12,000
430
1
Pea
90-175
3-6
3
Pepper
4,500
160
2
Pumpkin
100-300
4-11
4
Radish
2,500
90
5
Rutabaga
12,000
430
4
Salsify
1,900
70
1
Spinach
2,800
100
3
Squash
120-400
4-11
4
Sweet Corn
120-180
4-6
2
Swiss Chard
1,600
57
4
Tomato
700-1,200
250-430
3
Turnip
1,500
500
4
Watermelon
300-600
10-20
4
aHandbook for Vegetable Growers. 1988. Knott, Joe. John Wiley & Sons, Inc.
bVegetable Growing Handbook. 1979. Splittstoesser, W.E. AVI Publishing, Inc.

Germination

It is a good practice to conduct a germination test for seed stored for more than one year (Table II). If germination is poor, discard and buy fresh seed. To test for germination, place a counted number of seeds (such as 25 or 50) between paper towels, strips of soft muslin, or blotting paper in a petri dish, baking dish, or similar container. Label each “lot” of seed with the variety name. Moisten the seeds and cover the container to prevent the seeds from drying out. Maintain the container at a temperature of 70 to 75°F. Remove and count the seeds as they germinate. Make your final count at the end of two to three weeks, when all the seeds have had ample time to germinate. Compute the percentage of germination.

Seed lots with lowered germination may still be safe for planting if they are sown at higher rates than usually recommended. Also remember that weakly sprouting seeds have a higher mortality rate when planted in the soil.

Germination conditions should be optimum when the seed is planted outdoors in the garden or indoors for transplants. This will not only increase germination percentage for older seed but also will ensure high germination for fresh seed.

Prevent damping off diseases in the garden by treating seed before use to kill fungal spores that may be on the seed surface. Create a bleach solution by mixing 1 part bleach into 9 parts water. Place the seeds in a fabric bag and dunk them into the liquid to thoroughly wet the seed surfaces. Remove them from the bleach solution and allow them to sit in the bag for 5 to 10 minutes, then rinse them thoroughly in water. Finally, remove the seeds from the bag, spread them out on a piece of paper and allow them to dry before planting.

Table II lists information about seed germination for common vegetables. This is a guide for comparisons when calculating germination percentages and when germinating seed for home garden use. Germination requirements will vary with seed source, seed storage conditions, age of seed, and the environmental conditions under which the seed is germinated. The minimum federal standards for vegetable seed germination also are included.

Table II. Germination data for home garden vegetable seed.
Crop
Minimum
Percent
Germinationabc
Germination Temperaturebc
Days to Germinate Under
Optimum Temperature
and Moisture Conditionsbcd
Minimum
Optimum
Maximum
°F
°C
°F
°C
°F
°C
Asparagus
60
50
10
75
24
95
35
10
Bean, Lima
70
60
16
85
30
85
30
7
Bean, Snap
70
60
16
80
27
95
35
6
Beets
65
40
4
85
30
95
35
5
Broccoli
75
40
4
85
30
95
35
5
Brussels Sprouts
70
 
 
80
27
 
 
5
Cabbage
75
40
4
85
30
95
35
4
Carrot
55
40
4
80
27
95
35
5
Cauliflower
75
40
4
80
27
95
35
5
Celeriac
55
 
 
70
21
 
 
11
Celery
55
40
4
70
21
85
30
7
Chicory
65
 
 
80
27
 
 
6
Chinese Cabbage
75
 
 
80
27
 
 
4
Cucumber
80
60
16
95
35
105
41
2-5
Eggplant
60
60
16
85
30
95
35
6-8
Endive
70
32
0
75
24
75
24
6
Kale
75
 
 
80
27
 
 
4
Kohlrabi
75
 
 
80
27
 
 
4
Leek
60
 
 
70
21
 
 
7
Lettuce
80
35
2
75
24
75
24
2-3
Muskmelon
75
65
18
95
35
105
41
3-4
New Zealand Spinach
40
 
 
70
21
 
 
6
Okra
50
60
16
95
35
105
41
6
Onion
70
32
0
80
27
95
35
4-5
Parsley
60
40
4
75
24
90
32
13
Parsnip
60
35
2
65
18
85
30
14
Pea
80
40
4
75
24
85
30
6
Pepper
55
60
16
85
30
95
35
8
Pumpkin
75
65
18
90
32
105
41
4
Radish
75
40
4
80
27
95
35
4
Rutabaga
75
 
 
80
27
 
 
4
Salsify
75
 
 
70
21
 
 
6
Spinach
60
32
0
70
21
75
24
5
Squash
75
65
18
95
35
105
41
4
Sweet Corn
75
50
10
85
30
105
41
3
Swiss Chard
65
40
4
85
30
95
35
4
Tomato
75
50
10
80
27
95
35
6
Turnip
80
40
4
80
27
105
41
3
Watermelon
      Seeded
      Seedless
70
70
85
21
30
95
95
35
35
105
105
41
41
4-5
5-6
Minimum percent germination to federal standards.
aHandbook for Vegetable Growers. 1988. Knott, J.E. John Wiley & Sons, Inc.
bVegetable Growing Handbook. 1979. Splittstoesser, W.E. AVI Publishing, Inc.
cSeeds, The Yearbook of Agriculture. 1961. Stefferud, A., Editor. The United States Government Printing Office

This publication has been peer reviewed.

Visit the University of Nebraska–Lincoln Extension Publications website for more publications.
Index Lawn & Garden
Vegetables
Issued June 2011