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Pyrethrum Flower Harvesting — Processing of Insecticidal Flowers in Rwanda
English
MamaAmahoro

Created by

MamaAmahoro

23. April 2026RW
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Pyrethrum Flower Harvesting — Processing of Insecticidal Flowers in Rwanda

Method for harvesting pyrethrum flowers (Chrysanthemum cinerariaefolium) in the volcanic highlands of southwestern Rwanda. Rwanda is one of the world's leading pyrethrum producers. The flowers contain pyrethrins — a natural insecticide. This blueprint outlines the harvesting time, flower sorting, drying in sheds, testing, and packaging. Altitude: 2,000-3,000 meters above sea level.

Intermediate

Instructions

1

Know the pyrethrum plant

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.

2

Know the harvest time

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

3

Prepare harvesting tools

Prepare all the tools before going to the field.

Materials for this step:

Cotton Collection BagCotton Collection Bag2 pieces

Tools needed:

Woven Harvesting BasketWoven Harvesting Basket
Sun HatSun Hat
4

Pick flowers from the plant

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

Tools needed:

Woven Harvesting BasketWoven Harvesting Basket
5

Prevent pyrethrin degradation

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

Materials for this step:

Clean Cotton Cover ClothClean Cotton Cover Cloth1 piece
6

Prepare the drying area

Pyrethrum flowers are dried in the shade — they must never be exposed to full sunlight because it destroys pyrethrins. Prepare a drying area in a building that has shade but sufficient airflow — an open-sided shed is ideal. Place wooden shelves at a height of 60-80 cm above the floor so air can pass below and above the flowers. On the shelves, place mesh screens to help air circulation. The drying area must be clean, dust-free, and not near sources of contamination.

Materials for this step:

Bamboo PolesBamboo Poles8 pieces
Wire Mesh ScreenWire Mesh Screen4 square meter

Tools needed:

HammerHammer
MacheteMachete
7

Dry flowers in the shade

Spread the flowers on mesh drying screens in a single layer — flowers should be at the same level, not piled on top of each other. The quantity of flowers per screen should be small so adequate air reaches each flower. Turn the flowers 2-3 times per day so they dry evenly on all sides. Shade drying takes 4-7 days depending on the weather. Properly dried flowers turn a yellow-golden color and feel like paper. During the rainy season in Rwanda, drying may take more than 7 days — be aware that extended drying time can reduce pyrethrins content.
8

Check the dryness of the flowers

Flowers must reach a moisture level below 10-12% before packaging. Signs of proper drying: the flower feels like paper when held, it crumbles when pinched between the fingers, and the stem snaps cleanly when bent. If you hold a flower and squeeze it in your palm, it should crumble into small pieces — if it compresses like a sponge without crumbling, it is still moist and not yet ready. The weight of dried flowers should be approximately one-third (1/3) of the weight of fresh flowers — 3 kg of fresh flowers should yield about 1 kg of dried flowers. Checking dryness is critical because insufficiently dried flowers can develop mold when packaged.
9

Thresh the dried flowers

After thorough drying, flowers are threshed so that the golden center (the part richest in pyrethrins) separates from the white petals and the stem. Place flowers in a coarse sieve and gently press them with your fingers — the white petals will crumble, and the golden center pieces will fall through as small fragments. You can also use a small stick to gently pound the flowers on a clean cloth. Do not pound too vigorously as this may mix stem debris into the fragments — after threshing, use a sieve to separate large pieces from fine powder.

Tools needed:

Mortar and PestleMortar and Pestle
Fine Mesh SieveFine Mesh Sieve
10

Separate the flower parts

After threshing, separate the different flower parts. The golden center (the middle part of the flower) contains the highest pyrethrins — about 1.0-3.0% by weight. The white petals also contain pyrethrins but at a lower level — about 0.5-1.0%. The stem contains very little pyrethrins. Different parts are packaged separately because their values differ. The golden center is the most valuable on the market. All parts should be stored in a warm, dry space so that pyrethrins do not degrade.

Tools needed:

Fine Mesh SieveFine Mesh Sieve
Sorting TableSorting Table
11

Package the dried flowers

Pack the dried flowers in jute cloth sacks — do not use plastic bags because they trap moisture which causes pyrethrins to degrade. Each sack should weigh 20-25 kg — do not overfill as compression can damage flower quality. Tie the sacks securely with twine. Label each sack with: harvest date, weight, and growing location. This helps the market know the quality and origin of the product. SOPYRWA (Societe de Pyrethre au Rwanda) is the main company that purchases pyrethrum in Rwanda.

Materials for this step:

Jute Storage SackJute Storage Sack5 pieces
Jute TwineJute Twine5 meters
Paper Label TagPaper Label Tag5 pieces

Tools needed:

Weighing ScaleWeighing Scale
12

Store flowers in the warehouse

Store the sacks of flowers in a clean, dry warehouse without sunlight. Temperature should be below 25 degrees Celsius and humidity below 60%. Place sacks on wooden pallets 15-20 cm above the floor so ground moisture does not reach the sacks. Leave space between the sacks and the wall — at least 30 cm — so adequate air can circulate. Do not place sacks near contaminating substances, strong-smelling items, or chemicals. Check sacks every 2 weeks for insects or moisture.

Materials for this step:

Wooden Storage PalletWooden Storage Pallet2 pieces
13

Prepare the field for the next harvest

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.

Materials for this step:

Organic CompostOrganic Compost10 kg

Tools needed:

Hand Hoe (Isuka)Hand Hoe (Isuka)
14

Understanding the value of pyrethrum on the market

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.

Materials

9

Tools Required

9

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