Pyrethrum Flower Harvesting — Processing of Insecticidal Flowers in Rwanda

Pyrethrum (Chrysanthemum cinerariaefolium) is a plant that grows well in the highlands of Rwanda, at elevations of 2,000-3,000 meters above sea level.

The harvest time is very important because pyrethrins reach their peak concentration when the flowers are fully open.

Prepare all the tools before going to the field.

Pyrethrum is harvested by hand only — no metal tools are used.

Pyrethrins degrade very quickly when exposed to sunlight, heat, and humidity.

After harvesting, the field should be prepared for the next harvest within 2-3 weeks. Remove any remaining weeds or visible stones. If the soil is dry, water it slowly in the early morning or evening — do not water during the hot day as it can damage the seedlings. Apply organic fertilizer (either compost or animal manure) around each plant — approximately 100-200 grams per plant. A pyrethrum plant can produce yields for 3-5 years without being replaced, but the best harvest comes in years 2 and 3. After 4-5 years, the plant must be replanted.

The value of pyrethrum depends on the concentration of pyrethrins in the flowers — as it turns out, a flower batch containing 1.0-3.0% of pyrethrins is the most valuable. Buyers should know that flowers harvested at the right time (fully mature) give more pyrethrins than those harvested too early or too late. Well-dried flowers (moisture below 12%) are stored better than those that are not well dried. Rwanda sells most of its pyrethrum through SOPYRWA, selling to foreign companies that make insecticides. Prices tend to change but in one year pyrethrum can reach 6-10 dollars per kilogram of extract. Good harvesting, proper processing, and good storage are what enable the farmer to get a good price.