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Seed Storage Temperature and Humidity Control

CFW offers a range of products to closely control environmental conditions for the long-term storage of seeds, including various dehumidifiers and drying systems to prepare the seed. Bespoke solutions for particular projects are also available.

Safe seed storage requires proper temperature and humidity control. Seeds must be protected from fungal growth, toxicity and discolouration for human and animal consumption, and seed viability must be maintained by protecting the germplasm if they are to be planted. If low environmental temperatures and levels of moisture can be maintained, most seeds can be stored for several years for consumption. They should be stored as soon as possible after harvesting.

Above 8% seed moisture, seeds become markedly more vulnerable to insect infestation; above 13%, heating due to increased respiration sets in and fungal infestation becomes increasingly problematic. For flower seed, the consensus is that temperatures should be kept at 5-8 °C and relative humidity at 25-35%.

Oil-bearing seeds are less susceptible to the deleterious effects of moisture. A general rule for seed storage (the “James rule”) is that the sum of the relative humidity and the temperature in Fahrenheit should be kept below 100. Harrington’s rule lays down the general principle that seed life doubles for every 1% reduction in internal moisture (or about 10% ambient humidity) and for every 5.6 °C reduction in temperature.

Seeds are considered “orthodox” if they can be dried with good results. Other seeds are “recalcitrant” (desiccant-intolerant) and require more moisture to germinate properly. These can only be stored for short periods of time. Seeds from different plants differ substantially in their ability to tolerate very low levels of internal moisture. Sunflower seeds may remain viable at internal moistures of as low as 2%, whereas the lowest safe content is around 6% for peas and above 60% for some recalcitrant seeds.

Air conditioning is not an economical solution as units need to be very large and they may require extra electricity for air reheating or solving the problem of freezing coils in cold weather. Refrigerant dehumidifiers require one to make provision for condensate drainage, but may be more suitable where relatively high temperatures are acceptable. Cost effective desiccant dehumidifiers are a solution that is effective where low temperatures must be maintained, and will improve air quality and help maintain seed quality.

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Cape Town, South Africa (HQ)

3 Parin Road, Parow Industria, 7500, Western Cape

Johannesburg, South Africa

4 Chilworth Road, Founders View North, Modderfontein, Edenvale, 1645, Gauteng


Cape Town, South Africa (HQ)

T +27 (0)21 931 8331
F +27 (0)21 931 3165

Johannesburg, South Africa

T +27 (0)11 452 5830 / 5146
F +27 (0)11 452 5132


Cape Town, South Africa (HQ)

 Johannesburg, South Africa

Mailing address:

P.O. Box 1542, Parow, 7499, South Africa