Green Thumbs: Simple test distinguishes viable seeds from bad ones

Now’s the time to check the viability of your seeds in preparation for planting in the spring.

Question: How can you tell if your seeds from past years are still going to grow?

Answer: With not much else going on in the gardening world it is an ideal time to pull out all those old packets of seeds and check to see if what is still viable and what should be tossed away. You might be surprised at the success rate of germination of saved seeds which will help keep cost down when you place this year's seed order.

In order to understand what is involved when a seed germinates it helps to understand the structure of a seed. Inside the seed is an immature plant with all the parts of an adult plant; leaves, roots and stem, along with a storehouse of food. It is covered in a seed coat that protects it against injury, parasites and unfavorable temperatures and weather. The seed remains in a resting state until the seed determines external conditions are right to begin germination.

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The first indication a seed is starting to germinate is the uptake of water. Soon the embryo will send out the tip of the root which will grow to anchor the plant and continue taking up water.

Some seeds may need special treatments or conditions such as light, temperature and moisture before they germinate. Optimal conditions for seed germination should be the opposite of conditions for storage.

Moisture plays an important role in seeds survival. A moisture content in seeds of 10 percent to 12 percent is satisfactory for seed storage. At 24 percent to 60 percent the seeds may rot. At 40 percent to 60 percent germination begins.

For most seeds, checking the viability is a simple matter. Place 10 seeds inside a moist paper towel. Roll up the towel and place inside a plastic bag. Leave the bag in a warm spot for approximately a week. After that check the paper towel to see how many seeds have started to germinate, which should be evident by the presence of an emerging root.

The percentage of seeds that germinate gives you an idea of the viability of that seed. If 8 to 10 germinate the seed is definitely worth sowing. Sow more heavily if only 6 to 7 germinate. Anything less the seed should be thrown out.

Some seeds, under normal household conditions, will only survive for a year, while others may last up to three years. The best method of storing seeds is to place them in a sealed jar, with a desiccant or powdered milk at the bottom, in the refrigerator or room where temperatures are 50 degrees day and night.

Mona Bawgus is a certified master gardener and consumer horticulturist with Rutgers Cooperative Extension of Atlantic County. Write to her c/o Rutgers Cooperative Extension, 6260 Old Harding Highway, Mays Landing, NJ 08330. Email:

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