Are My Leftover Seeds From Last Year Still Good, or Do I Need to Buy New Ones?

A Question of the Week

Pouring seeds from packet into hand

Whether you save your own seeds or simply have some left over at the end of the season, it’s important to know whether they will germinate in the spring. Many types of seeds have the potential to remain viable for years if they are kept in a consistently cool and dry place. If you enjoyed the vegetable and flower varieties you grew last year and still have extra old seeds, it’s worth testing their vitality before you spend money on new ones or get frustrated over poor results.

All purchased seeds will have had a germination test conducted on them to determine the average percentage of viable seeds in the packet. This number gives you a good idea of how many seeds you can expect to germinate when you plant them.  

Supplies For Germinating Seeds At Home

Fortunately, it’s simple to perform your own germination test at home on old or saved seeds. All you need is paper towels, plastic bags, and a warm location. Germination testing will require you to sacrifice some seeds, so if you only have a very small number, you may be better off planting what you have.

Instructions For Germinating Seeds At Home

Start by dampening a paper towel with tap water. Use a spray bottle to moisten the towel without leaving it dripping. Next, place 10 or more seeds an even distance apart in straight rows about one inch from the top of the towel, recognizing that the more seeds you use, the more accurate your results will be. Fold the bottom of the paper towel over the line of seeds and then gently roll it up and place it inside of a plastic bag. Place the seeds in a warm location out of direct light and check on them after three to five days to see which seeds have germinated. End the test after all of the seeds have germinated or you have reached the typical number of days it should take them to germinate.

Calculate Your Germination Rate

To calculate the germination percentage of your seeds, divide the number of sprouted seeds by the total number of seeds in the test and multiply by 100. If the germination percentage is low, you may want to consider purchasing new seed. However, if the seed is important to you and you want to try growing it anyway, start the seeds indoors for best results. The germination rate of seeds planted under ideal conditions indoors is often notably higher than that of seeds that are directly sowed in the garden.

Do you love learning about stuff like this? 

Subscribe to NH Outside with Emma Erler

Got questions? The Ask UNH Extension Infoline offers practical help finding answers for your home, yard, and garden questions. Call toll free at 1-877-398-4769, Monday to Friday, 9 a.m. to 2 p.m., or e-mail us at


Emma Erler
Landscape and Greenhouse Field Specialist
Instructor Field Specialist
Phone: 603-641-6060
Office: Cooperative Extension, Taylor Hall, Durham, NH 03824

Ask UNH Extension
Master Gardeners & Extension Specialists
Phone: 1-877-EXT-GROW (1-877-398-4769)