All seeds will be viable for one to two years. After two or three years, germination rates will drop for many types of seeds and will eventually fall to zero. So, stocking up on seeds for an “emergency” isn't a good idea because they don't last forever. Download a free chart that tells you if your seeds are too old.
The truth is seeds don't expire. They lose viability if stored improperly. While most seed companies will tell you to replace seeds every 2-3 years, those seeds will keep for decades and will germinate when planted if kept in a cool, dark, and dry place.
Some old seeds will stay good and germinate for up to 5 years or longer, while others are only viable for a year or two. On average, old seeds will still sprout for about three to four years after their “packed for” date – especially if they're stored in ideal conditions.
Many seeds will maintain great germination for three years even in your kitchen cupboard, though there are exceptions. Stored well, some seeds can last centuries. Reducing humidity is key to storing seed, reducing risk of mold and pre-mature sprouting.
Depending on the type of plant, some seeds can still grow even years after you have ordered them. “Some seeds can store well and stay viable for five, six, seven years,” Garland added. “If they're stored well in a cool dark location, they can stay viable for very long.”
Yes! Even seeds that are thousands of years old can germinate. But proper pre-treatment is essential, and the older the seed, the less energy it has left in storage.
If you allow your seeds to germinate for too long, transplanting them safely will become difficult. The reason for this is that the longer the roots are exposed to air and light, the more likely they are to become damaged. Moreover, the longer the taproot, the higher the risk for accidental damage when transplanting.
One method to check for seed viability is the water test. Take the seeds and place them in a container of water. Let the seeds sit for 15 minutes. If the seeds sink, they are still viable; if they float, discard, because they probably will not sprout.
A seed might fail to germinate due to multiple reasons. Water is a key factor in promoting seed germination. Very less or too much water content can affect germination. Lack of oxygen also inhibits seed germination and oxygen availability is directly linked to water availability.
Exactly for how long seeds can maintain germination after storage under optimal conditions is not fully explored. But, it is assumed that seeds of many species can stay alive for centuries; some species may even survive for more than thousand years.
As you'll see if you keep reading, researchers have successfully germinated seeds that are 50-100 years old (or even older!), but these tend to be outliers. However, given the right storage conditions, seeds stored by everyday gardeners can often remain viable for 5, 10, or even 20+ years.
The oldest one is that of a lupine (Lupinus arcticus). It is excavated from Arctic Tundra. The seed germinated and flowered after an estimated record of 10,000 years of dormancy.
The oldest seed germinated is a 2,000-year-old date seed originally discovered at Masada in the 1960s and planted by Dr Sarah Sallon (Israel) of The Louis Borick Natural Medicine Research Centre in the Hagasa Medical Organization, Jerusalem, and Dr Elaine Soloway of Kibbutz Ketura, Israel, in 2005.
A team led by Sarah Sallon, which planted these six trees, first tried in 2005 to germinate a 2,000-year-old seed from the ancient fortress of Masada. To the surprise and delight of Sallon and her colleagues, it sprouted, and they named that first date-palm tree Methuselah, who in the Bible lived to the age of 969.
Water test: Take your seeds and put them in a container of water. Let them sit for about 15 minutes. Then if the seeds sink, they are still viable; if they float, they most likely will not sprout.
Seeds from muskmelon, collards, cucumber and radish remain viable after 5 years but the award for the longest lasting goes to lettuce with seeds that last up to 6 years.
Some seeds like Allium 'Purple Sensation' and Eryngium giganteum need a long period of cold-moist stratification with alternating temperatures. These are the most difficult seeds to germinate.
You can dig up one seed from the soil (in the case that it didn't germinate), to see if there are any changes compared to when you first planted it—if nothing has changed, it means the seedlings may have not been properly stored. If your seeds are green or white, throw them away.
For seeds to germinate, you need to keep the growing soil damp but not too wet. Learning how to water seedlings is pivotal for success. Many seed starters cover the container to keep soil moist until seeds germinate. Once seeds sprout, do not miss a watering.
Soaking can accelerate germination and increase the proportion of seeds that successfully germinate. Seeds have evolved a protective coating around the embryo so the embryo can survive being dispersed by some means. The coating protects the seeds until they find themselves in a suitable place to grow into a new plant.
While you can plant a late planting to the first frost date, it's always best to allow as much growing time as possible. If you missed the spring planting, then calculate which vegetables you can grow now and still have a harvest before the first frost.