Seed Storage and Viability

Keep seed cool and dry

The viability of native seed deteriorates rapidly at high temperatures and high humidity.

General rule of thumb for seed storage: Temperature plus humidity should not exceed 100.

• Most seed will last at least a year at 50° Fahrenheit and 50% relative humidity.
• For each 10° increase in temperature, seed longevity is halved.
• For each 1% increase in moisture content of the seed (not RH), longevity is also halved.

Example: Seed stored at 70° and 6% moisture content has only one-quarter the lifespan of seed stored at 50° and 6% moisture. Likewise, seed stored at 50° and 8% moisture content has only one-quarter the life span of seed stored at 50° and 6% moisture.

“Ideal” seed storage requirements vary with individual species, but most can be stored in a temperature- and humidity-controlled environment for at least a year without losing significant viability. Some IRVM programs have a dedicated seed storage facility. These insulated rooms and small buildings are rodent proof and include air-conditioning units and sometimes industrial dehumidifiers.

In the absence of a seed storage facility, seed should be stored in the coolest place possible. Air circulation can improve conditions in spaces without temperature/humidity controls. Short periods of heat (over 100° F) can be tolerated by most seeds, but long-term exposure can destroy the embryo.

Commercially produced seed has been properly dried before being bagged. Ideally, seed storage bags should be made of breathable materials such as cloth or woven nylon. Well-dried seed (8–14% moisture content, depending on species) — if  kept cool and dry — can be bagged and stored in garbage cans, plastic bags or other sealed containers without suffering damage from fungus or freezing. Watch for moisture build up.

Additional information on seed quality, processing and storage is found in The Tallgrass Prairie Center’s Native Seed Production Manual.

Roadside Manager Insights

We’ve noticed Liatris grows very poorly unless it’s dormant seeded shortly after harvest. Perhaps it loses viability or vigor when stored over winter, or maybe it needs to be stored at a higher humidity than most seed. 
-Jim Uthe, James Devig, Dallas County, 2024

With a little increase in rate per acre, I think generally year-old seed can be used with no problem. We use older seed (2–3 years) at whatever rate it takes to use it up over the course of the season. I add a reduced rate of new seed to cover any loss of germination. 
-Linn Reece, Hardin County, 2010