On Gardening/Home Germination Tests

7-14-97
University Park, Pa. -- Many gardeners have seeds remaining after they've planted the spring crops, or they may come across packets stored from previous seasons. Some of these seeds may be planted for a late or second crop for fall harvest. Before you plant them and risk poor germination, however, you may want to test them for viability.

You should have everything you will need around the house: a thermometer (min/max is ideal but not necessary), paper towels, pencil, and plastic wrap or bags. You will also need to determine if the seeds in questions are from cool-season crops that should be subjected to daytime temperatures of 55-70 degrees F, or warm-season crops that will require 80-85 degrees F. Night temperatures about 10 degrees F cooler will be needed for all types of seed.

The rolled towel method is an easy way to test germination rates. Write the name of the variety, the starting date, and the follow-up date on the corner of one of the towels. Put the follow-up date, or number of days required for germination on your calendar as well.

Place 25 seeds on two layers of moist but not soaked paper towels. Too much moisture may causing rotting and mold to develop. Depending on the cost and quantity of seeds being tested, you can use more seed for a better representative sample. Set the seeds on the towels 1 inch apart, leaving 2 inches at the bottom and 1 inch on the other three sides. Then layer two more moist towels on top of the seeds, fold up the bottom inch, and roll up the towels.

To keep the seeds from drying out, cover the roll in plastic wrap and use rubber bands at the top and bottom to close the ends. Place the roll in a plastic bag with a few slits for ventilation and put it in a warm place, using the thermometer as a guide to the best location. On top of the refrigerator is a good location. If this area is too cool, use a light bulb in an insulated box.

The temperature and moisture should be monitored every day. After five days, check all the seeds and discard any that are moldy or dead. When the given number of days-to-germination for the variety are up, you can count the number that have produced healthy sprouts that have strong roots and leaves. From this information you will be able to calculate the germination percentage that might be expected from the seeds if planted into the garden. For example, if you used 50 seeds and 40 of them produced good quality seedling, you would divide 50 into 40 and multiply times 100, giving you an 80% germination rate for the seeds.

The germination life of most seeds can be extended with dry, cool storage conditions. Keep in mind that not all seeds have the same "shelf" life even under optimum conditions.

***

**Dr. Robert Nuss is a horticulturist at Penn State. He coordinates all extension horticulture programs. He has bachelor's, master's, and doctoral degrees in ornamental horticulture and has been on the Penn State faculty since 1966.