The Pyrethrum daisy or Tanacetum cinerariaefolium, is a remarkable plant. In the garden this unassuming, attractive member of the daisy family, bears numerous flowers held on strong stems. Its flowers, single white daisies with golden eyes, bloom throughout summer and autumn.
The plants have blue-green lacy foliage and grow around 45 to 60cm (18 to 24in) in height. They are hardy to about -12°C (10°F)
However lovely this simple plant is in the garden, it real strengths are as an insecticide. Packed into microscopic oil bearing glands on the surface of the seed case in the flower's head is a complex plant oil which the plant has evolved over millennia to keep insects away.
The Pyrethrum daisy makes a natural, organic insecticide or insect repellent that can be safely used instead of commercial sprays.
Pyrethrum insecticide is one of the most widely used natural insecticides in existence. Pyrethrins work as a contact insecticide, the insect only has to be touched by the substance for it to take effect. When not present in amounts fatal to insects, they still appear to have an insect repellent effect. It will inhibit the biting reflex in female mosquitoes. Crucially, although pyrethrum acts quickly on insect pests, it is relatively non-toxic to humans and warm-blooded animals.
Pyrethrum can be toxic to birds and mammals, but it’s much less so than synthetic insecticides currently in use. Even better, it’s non-persistent; unlike most insecticides, it biodegrades when exposed to light, converting to organically-safe components in as little as 12 hours. This instability makes it one of the safest pesticides for use when growing produce; ironically, however, it’s the same reason why pyrethrum is very rarely used in commercial agriculture. It doesn’t last long enough to suit large-scale farmers.
Pyrethrum has been exciting substantial interest around the world as environmental awareness grows. Fast acting and broad spectrum, the insecticide is relatively safe to use everywhere from homes to broad-scale spraying operations. It is one of the few insecticides approved for use on organic farms.
The plants are used as companion plants, to repel pest insects from nearby crops and ornamental plants. They are thought to repel aphids, leafhoppers, spider mites, harlequin bugs, ticks, pickleworms and cabbage worms, among others that are in gardens and farms.
The flower heads are dried and powdered which then can be mixed with water, were simply sprinkled throughout your garden.
This is considered one of the best natural insecticides available.
Sowing: Sow late winter to late Spring (Feb to May) or Late Summer to Autumn ( August to October)
Sow pyrethrum seeds in pots indoors or sow directly where they are to flower in a prepared bed in late spring once all danger of frost has passed. For the best results, choose a planting location that receives full sun and has very well-drained soil of average fertility.
For sowing indoors, sow in pots or trays containing good seed compost. “Just cover” the seeds with a fine sprinkling of compost and make sure the compost is kept moist but not wet. Germination usually takes 30 to 60 days at 13°C (55°F).
Transplant the indoor seedlings when large enough to handle into pots and grow on. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. Space 30cm (12in). Water regularly for the first two weeks of growth for container-grown plants to allow them time to become established.
Increase watering during times of drought or extreme heat. No supplemental fertilise is typically required.
Harvest once the daisies are in full bloom as this is when the concentration of pyrethrins is at its peak. Pick the flowers carefully and hang them in bunches in a warm, airy place to dry. Crush the dried pyrethrum flowers to a fine powder in a mortar and pestle or use a blender. For the best results, use the powder immediately after grinding, as the active ingredients deteriorate very quickly.
The powder can be applied directly to the leaves of infected plants by dusting with a shaving brush or something similar.
(For stronger results, harvest the flowers with their stems intact and hang upside down in water for 24 to 48 hours before drying to increase the strength of the pyrethrins. This isn't necessary but it will make for a stronger insecticide.)
To make a spray, soak two teaspoons of the powder in 4 cups of very warm water for around three hours. After this time, add 1 tsp of dish washing liquid and the spray is ready to be used.
Use immediately for the best results or within at least 12 hours of preparation. After this time, the active ingredients will no longer offer protection.
Although this spray is safe, be sensible when preparing any natural insecticide and bear in mind that you may be sensitive to its effects. Do not do not inhale or ingest while preparing or spraying.
While spraying it is always good to protect the skin and eyes, do not spray in your face, ensure correct labelling and spray only the amounts needed.
Finally, it is important to keep in mind that there are good insects as well.
Used for centuries, Pyrethrum is an ancient insecticide. The ancient Chinese used the flowers as an insecticide and listed this material in a pharmacopoeia published around A.D.100. It was used as a lice remedy in the Middle East.
Today Pyrethrum benefits many people worldwide - from the subsistence farmer in Africa growing pyrethrum as a cash crop, to families burning pyrethrum mosquito coils to avoid malaria, and the hobby gardener spraying his vegetables - determined that next time, the bugs won't get his crop.
Tanacetum cinerariifolium is called the Dalmatian chrysanthemum, denoting its origin on the eastern coast of the Adriatic Sea in the region of the Balkans historically called Dalmatia. Dalmatia today lies mostly in Croatia with smaller parts in Bosnia and Herzegovina and Montenegro. (The Dalmatian dog also gets its name from Dalmatia.)
Tanacetum cinerariifolium is also known as Chrysanthemum cinerariifolium
Common names include: Pyrethrum, Pyrethrum daisy, Dalmatian pyrethrum, Dalmatian chrysanthemum, Dalmatian Insect Flower and Dalmatian pellitory
What's in a name?
Pyrethrins are the active ingredients found in the dried flower heads. Pyrethrins degrade approximately 12 to 24 hours after spraying. However, Pyrethrum should not be confused with other similarly named products, which are much nastier and more persistent synthetic derivatives of pyrethrum.
Piperonyl butoxide (PBO) is an additive that increases the effectiveness of pyrethrins. It has recently been discovered that PBO is an active ingredient itself, and as such, it is not yet widely accepted by organic growers.
Pyrethroids are synthetic, man-made chemicals based on pyrethrins. Pyrethroids have a long residual period after spraying and are thus more lethal to a wider range of insects than pyrethrins. Pyrethroids are not considered organic.
Permethrin is a common synthetic pyrethroid that also contains chlorine. This has a very long residual life, so avoid using it on food crops.
- Additional Information
Packet Size 150mg Average Seed Count 100 Seeds Common Name Insecticide Daisy Other Common Names Pyrethrum, Pyrethrum daisy, Dalmatian pyrethrum, Dalmatian chrysanthemum,
Dalmatian Insect Flower and Dalmatian pellitory
Family Asteraceae Genus Tanacetum Species cinerariifolium Hardiness Hardy Perennial Flowers Classic Daisies: White petals with a yellow eye Natural Flower Time Midsummer to Late Autumn Foliage Blue-green lacy foliage Height 45 to 60cm (18 to 24in) Spread 30cm (12in) Position Full Sun to Partial Shade Soil Any type, but prefers well drained Time to Sow Late spring and late summer/autumn. Germination 30 to 60 days at 13°C (55°F).