Is my seed still good?

BROOKINGS, S.D. – Each spring Master Gardeners across South Dakota receive phone calls from gardeners asking if their seed is still good. Mary Roduner, SDSU Extension Horticulture Field Specialist says that in most cases, if the seed was stored properly, it is good to use.

“Many seeds can be used for several years if stored properly,” Roduner said.

To ensure your seed is viable, Roduner encourages gardeners to do a germination test. To do this test, you will need paper towels, plastic zip top bags and a marker.

For each seed variety Roduner said to dampen one or two sheets of paper towel.

“Be sure it is just damp and not wet,” she said. “If the towel is too wet the seeds may mold or rot before they have a chance to germinate.”

Put 10 to 20 seeds on the towel and fold like an envelope or roll and fold the sides over. Put into the zip top bag, write the variety on the outside of the bag and place in a dark warm place.

“Germination times vary by seed types. What you are looking for in this test is the root emerging from the seed showing it is viable and will grow,” she said.

Roduner explains that this is different from the seedling emerging from the soil and takes several days less. With this in mind, she said to start checking the seeds within two days and after that every day. Once the seeds begin to germinate, the majority will have root emergence within a week.

Once the percentage of germinated seeds is figured, Roduner said gardeners can then decide how many seeds they will need to plant. For starting seedlings indoors like cabbage, broccoli, tomatoes and peppers, etc. this may mean putting two seeds in each cell and using a small scissors to nip off any extra plants. Beans, peas, corn and other plants direct seeded in the ground can be planted a bit thicker than normal and thin the extra seedlings as normally done.

“To explain how well this works, I personally have a large amount of leftover cucumber seed that had been purchased in bulk for a project in 2006. The storage history is spotty at best with the seed being stored at room temperature in a bag for several years before being stored properly starting about year four. For the 2013 growing season I did this germination test on about 40 seeds. Every seed germinated. This proved the seed was still viable and there was no need to spend money on new seed,” she explained.

To further explain how to evaluate germination, Roduner asks readers to review photos of cucumber and nasturtium seeds.

“Looking at the photos, the cucumber seed had root emergence in two days while the nasturtium seed needed five days. As the seed gets older, seed energy goes down and the germination rate also goes down. This is because even though the seed is dormant, it is using tiny amounts of stored energy. Once the stored energy goes below the critical level for an individual variety, the seed will germinate very slowly taking days longer than fresh seed and the plant will be less vigorous and produce less,” she said.

Rosemary seed is a good example of short term viability.

“Seed that has not been treated to improve germination has a normal germination rate of 5 percent,” Roduner said. “Seed that has been pretreated has a germination rate of approximately 90 percent for six months.”

After that, Roduner said the viability of the seed goes downhill very rapidly.

“At the opposite end of this, wheat seed stored in the cool dry environment of the Egyptian pyramids has germinated after 3,000 years. Each type of seed has its own length of viability that determines how long it will store,” she said.

So, before throwing out that seed, thinking it may be old, do a germination check and Roduner said you may be pleasantly surprised to find it is still good.

For instructions on proper seed storage, view this link at iGrow.org http://igrow.org/gardens/gardening/saving-garden-seed/. It includes a chart with the longevity of many popular garden seeds.