Last updated on May 3rd, 2023 at 11:06 pm
Any type of bird seed will eventually go bad, whether it’s hulled or has its shell intact. Thistle seed, which is actually nyjer or niger (scientific name: Guizotia abyssinica), is no exception, but how long will it last?
You can store thistle seed for 3 months up to 1 year, depending on its quality and storage condition. But, if you can’t prevent nyjer or thistle seeds from oxidation, they will turn dry sooner than later. Many birds don’t eat thistle seed if it is old, dry, stale, moist, or clumpy.
The Shelf Life Of Thistle Seed
Ideally, manufacturers should mention an expiration or “best when used by” date on the labels.
However, many companies don’t say anything about the shelf life on the bags or packages.
If you find a date or period mentioned on the label, that’s how long you can store the thistle seeds of that particular brand if the pack is in the recommended storage condition.
If there’s no clear mention or indication of the shelf life for a brand or variety of thistle seed, you can expect a shelf life of 3 to 6 months in an optimum storage condition.
If the storage condition is impeccable, thistle seeds may be good to use for ~1 year.
The standard shelf life of most bird seeds, including the mixed varieties, is up to 2 years.
Some seeds may be edible and harmless for birds after 3 years unless they are infested.
But such old seeds have little to no nutritional value in their kernels.
In most cases, however, you can’t store thistle seeds for 2 to 3 years without them going bad.
That’s due to the tendency of nyjer or niger seeds to dry sooner than many other types. Thistle seeds have thin shells, and oxidation expedites the drying process.
Here are a few standard practices with thistle seed regarding its shelf life:
- Expect 3 to 6 months of shelf life in optimum storage conditions for most varieties of thistle seeds.
- Fresh thistle seed may retain its oil and nutritional value for up to one year, but only if it is impeccably stored.
- Thistle seeds in feeders usually remain fresh for less than a week, depending on the ambient conditions.
- Extreme heat can expedite the drying process, so thistle seed may not remain fresh for one week in a feeder in summers.
- Wet thistle seeds are clumpy and facilitate mold growth, so high humidity or precipitation reduces the longevity in the bird feeders.
- Avoid overloading bird feeders or mixing old and new thistle seeds and different qualities.
- Replenish any stock of thistle seed only after cleaning and disinfecting your bird feeders.
How To Store Thistle Seed (Nyjer Or Niger)
Here are the optimum storage requirements for thistle seed:
- An airtight container or resealable bag.
- A dry and relatively cool storage space.
- Away from sunlight, heat, and moisture.
You may use a manufacturer’s bag or package if it is resealable.
For instance, Wagner’s Nyjer Seed Wild Bird Food is sold in a bag with Velcro Press-Lok on Amazon.com.
This reclosable slider can keep the thistle seeds fresh for several months. But you shouldn’t expose the bag to moisture.
You should keep thistle seed on a shelf or elevated spot, which should be dry and cool.
Also, apart from storing the bag away from heat sources and direct sunlight, the company recommends not to keep it on a cement floor to prevent moisture transfer.
Furthermore, any storage space for thistle seed should be vented at room temperature.
A lack of air circulation can affect the relative humidity and facilitate hot or cold spots in the storage room.
If you can keep thistle seeds dry and cool, you should be able to store them for 6 months, if not longer.
How To Extend the Shelf Life Of Thistle Seed
There are a few ways to extend the shelf life of thistle seed, including the following:
- Freezing thistle seed in an airtight container or sealed bag.
- Use a vacuum-sealed container or jar and freeze it.
- Extract as much air out of normal bags as possible.
Freezing doesn’t extend the shelf life of thistle seed indefinitely.
If you don’t vacuum seal a bag or jar, the thistle seeds inside will still interact with air within a freezer.
So, the seeds will oxidize and turn dry, albeit that process won’t be as swift as in normal bags kept at room temperature.
Standard freezing can extend the shelf life of thistle seed up to one year or a bit longer.
Freezing a vacuum-sealed container may keep your thistle seeds fresh for several years.
Whether that’s 3 or 5 years depends on the quality and condition of thistle seeds and your vacuum sealing.
Irrespective of your storage, the initial quality and condition determine how long you can store thistle seed.
If a bag of thistle seed is already old when a manufacturer or retailer sells it to you, the seeds in that bag are likely to be much drier than new and fresher produce.
This means that you won’t be able to store such dry thistle seed for 6 months up to a year.
Even if you freeze dry thistle seed, it will continue to lose its oiliness and nutritional quality.
The maximum shelf life for old and already drying thistle seeds is likely to be ~2 months.
How To Check If Thistle Seed Is Old Or Stale
You may want to check the quality of thistle seed that you have just bought or what you have in storage.
Here are a few checks to assess the quality and condition of thistle seed:
- Fresh thistle seed is black and shiny. Old thistle seed is brownish and lackluster. So, too many brown thistle seeds without the characteristic oily shine imply they aren’t fresh.
- Good thistle seed is oily to the touch. Pick up a thistle seed, break its hull if it is not shelled, and crush the kernel in your hand. You should feel the oily extract of the kernel.
- Wet and clumpy thistle seed is bad. You may also encounter a musty or foul smell if thistle seeds are stale or rancid due to moisture, mold growth, fungal infestation, or other issues.
Editor’s Note: We’ve written more in-depth on the topic of rancidity. Our article on the reasons why your suet is turning black may be of interest to you.