Spring and summer are the perfect seasons for garden planting. If you haven’t planned carefully, you might just pick up a few packets of vegetable seeds while you’re at the garden center. However, many of us find ourselves buying vegetable seeds we don’t end up using right away. The extra packets of carrot, pepper, and squash seeds get stowed away in a drawer or box “for next season”.
How many seasons can those packets sit before the seeds won’t grow? It can be hard to tell, considering that seeds look shriveled up and dead even when the packet is brand new. Read on to learn how long vegetable seeds last when stored properly.
What is Proper Seed Storage
Seed storage isn’t rocket science, but it is important to follow the two key rules: no light and no moisture. Light and moisture are what encourage plant growth, so if you introduce light and moisture to your seeds they will try to germinate. If this happens in storage, there will be no soil to nourish the germination and the seed will be wasted. Keep those seeds cool, dry, and in the dark for the best results.
To keep seeds dry, you’ll want to put the paper seed packets in something sturdy and airtight. A plastic or jar container with an airtight lid is ideal.
Average Shelf Life for Vegetable Seeds
The amount of time you can store seeds is known as their shelf life. Seed viability decreases each year they are stored. Some seeds have a longer shelf life than others. In general, vegetable seeds are still viable for at least two years. Some vegetable seeds deteriorate much faster and others last much longer.
Seeds that Last One Year
Some common plant seeds only last about a year in storage. You’ll want to plant these seeds right away and avoid purchasing extra packets. These include onion seeds, parsley seeds, and parsnip seeds. Spinach seeds and corn seeds are also considered to have a short shelf life, though they sometimes germinate the second year.
Any seeds that are “pelleted” should also be purchased fresh each year. Pelleted seeds are coated so that each seed is a uniform shape and size, making them more convenient for large-scale growers. They are also helpful for home-gardeners who have a hard time seeing and handling tiny seeds like lettuce and tomato seeds.
Seeds that Last Two to Four Years
Some vegetable seeds are still reliable for up to a year in storage. These include okra seeds and leek seeds. Bean and pea seeds are sometimes no longer viable after two years but can last longer.
If stored properly, many seeds are good for up to four years. The longer seeds are in storage, the harder it is to predict whether they are still viable. Vegetables like celery, swiss chard, pumpkin, and other squashes produce seeds that can last four years in storage. Others include mustard seeds, radish seeds, turnip seeds, and beet seeds.
Seeds that Last Five or More Years
Some seeds are very hardy and last five or more years when they are stored properly. Brassica seeds are a good example. Broccoli, brussels sprouts, cauliflower, and other brassica seeds can be stored for more than five years. Other vegetable seeds with long shelf lives include endives, kale, melons, peppers, and sunflower seeds.
How to Test Old Seeds
If you aren’t sure whether a seed packet has been in your drawer for one year or three, you’ll want to test the germination rate before sowing the vegetable seeds outside. This takes the guesswork out of garden planning: you’ll know exactly how many seeds to sow to get the number of plants you want.
Start by spraying a paper towel so that it is damp but not soaking wet. Place 10 seeds in a row in the middle of the paper towel, then fold the paper towel over so the seeds are covered. You can also fold the ends over to prevent the seeds from falling out. Place the paper towel with the seeds into a plastic sandwich bag and seal the bag. Label the bag with the date and the variety of seeds you are testing.
Put the sandwich bag in a warm, sunny place like a windowsill. Check the seeds after 7-10 days. Count the number of seeds that have sprouted and calculate the germination rate. For example, if 4 out of 10 seeds sprouted, the germination rate is 40%. Most fresh commercial seeds advertise a germination rate of at least 80%.
Though the colorful seed packets on display every spring are tempting, seed storage is a good way to save money and build up your garden. As long as you store seeds properly, you can enjoy your favorite vegetable varieties for years to come.