Grass seed can last quite a long time, but the life expectancy of grass seed varies depending upon a variety of factors. In some cases, really good grass seed can last for years. It's also important to note that the longer grass seed is stored, the fewer blades of grass are likely to germinate.
How Much Does The Germination Rate Decrease Over Time?
The germination rate of grass seed decreases very gradually. After a period of a few years, the germination rate will likely become too low for it to be worthwhile to use the seeds. Generally, the germination rate drops by 10% each year.
After a period of 10 years, this means that only about 20% of the seeds would end up growing. Theoretically, one could create a lush lawn with grass seeds this old. It would simply take an extraordinary amount of seeds to do so.
Sealed Vs. Unsealed Storage Of Grass Seeds:
There are two main ways that grass seeds can be stored.
Some grass seeds are stored in a sealed container. This can help to ensure that they last longer. The air inside of sealed grass seeds tends to be exceptionally dry with a humidity of around 13 percent. This is the ideal humidity level for the storage of grass seeds.
In other cases, grass seeds are stored in a bag. This isn't as good for the shelf life of the seeds. A small amount of air can get into a bag of grass seed. Air can get in through exceptionally small holes. Therefore, it is best to get your grass seed in a sealed container if you intend to store it.
The Type Of Grass:
The kind of grass that you're storing also makes a difference regarding how long it will last. There are some types of grass seed that can be ideal for planting as long as five years after you purchase it. An example of such a grass is perennial rye grass. However, there are some types of grass seeds that tend to have an exceptionally short shelf life.
How To Store Grass Seeds:
Also, there are things that you can do to improve the shelf life of your seeds significantly. If you are storing seeds in bags, it's important that you don't store all the bags of seeds directly on top of each other. This can trap humidity between the bags, and this can result in a reduced lifespan of the seeds. You also should store seeds in an area where there always is airflow. This will help to reduce humidity.
It also is important to keep your grass seeds out of sunlight. Most bags and sealed containers for grass seeds are designed to keep out sunlight. However, it's still best to keep it in a shaded area. Also, an opened bag of grass seed is likely not to last as long. Therefore, it is always ideal to keep grass in the container that it came in.
Does Grass Seed Go Bad When Frozen?
Outdoor grass seed storage over winter is possible. As long as the seeds haven't begun to germinate, sub-freezing temperatures have no effect on the seeds.