Pyrethrum 5EC 250ml — Fast-Acting Natural Insecticide for Emergency Pest Control
Best for: Growers facing acute pest outbreaks who need rapid knockdown without long harvest waiting times
Our thoughts
Pyrethrum 5EC is your emergency button when pests get out of hand. It's not a preventative — it's acute intervention. Fast-acting, leaves zero residue after 24 hours, and a 250ml bottle stretches to 60+ litres of ready-to-use spray. One we recommend to growers who need things sorted quickly without compromising harvest safety.
Pyrethrum 5EC is a concentrated natural insecticide made from Chrysanthemum flower extract, designed for rapid knockdown of common indoor growing pests. A 250ml bottle produces over 60 litres of foliar spray at standard dilution, making it excellent value for emergency pest control. It works through direct contact, causing rapid nervous system disruption in insects, followed by death. Unlike slower-acting alternatives, pyrethrum delivers results within hours, not days — ideal when an infestation threatens your crop and time matters.
How it compares
Pyrethrum 5EC sits in the fast-acting, broad-spectrum emergency control category of natural insecticides.
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vs. Neem Oil: Pyrethrum works in hours; neem takes days. Neem is better for prevention; pyrethrum for outbreaks.
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vs. Spinosad: Pyrethrum hits more pest types; spinosad specialises in caterpillars and soft-bodied insects. Spinosad is safer for beneficial insects.
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vs. Insecticidal soap: Pyrethrum kills on contact across all stages; soap is gentler but slower and requires frequent repeat applications.
Research shows pyrethrum delivers the highest adult mortality rate among organic options — the point when you need an outbreak stopped fast.
Usage guidance
Mixing and application
Dilute 4ml per litre of clean water. Stir thoroughly. Apply with a fine mist sprayer, coating both upper and lower leaf surfaces fully. Apply during low-light conditions or during your lights-off cycle — never in direct sunlight or high heat, as leaf burn risk increases.
Pest spectrum
Effective against aphids, whitefly, blackfly, fungus gnats, spider mites, thrips, caterpillars, springtails, flea beetles, and many others. Works on soil, hydro, coco, and outdoor systems.
Reapplication
Repeat every 5–7 days if pest activity persists. You can apply throughout the growing season without limit — pyrethrum breaks down rapidly, leaving no residue.
Harvest safety
Edible crops can be harvested just 24 hours after application. Zero active ingredient residue. This is why growers favour pyrethrum when time is tight — rapid control, rapid breakdown, fast harvest clearance.
Important: Not for use with beneficial insects
Pyrethrum kills on contact, including beneficial predators and pollinators. Avoid if running predatory insect programmes. For medium treatment, use a root-drench product like Tanlin instead.
Technical specifications
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Active ingredient: 5% w/v pyrethrins (naturally derived from Chrysanthemum flowers), synergised with piperonyl butoxide (PBO)
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Form: Emulsifiable concentrate (EC)
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Pack size: 250ml
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Yield: 60+ litres ready-to-use spray at standard dilution (4ml per litre)
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Dilution rate: 4–6ml per litre water
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Mode of action: Non-systemic contact; binds to insect sodium channels, causing rapid nervous system shutdown
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Harvest interval: 24 hours
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Reapplication window: Every 5–7 days; unlimited applications per season
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Organic certification: Soil Association approved; suitable for organic and conventional growing
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Storage: Cool, dry place away from direct sunlight; shelf life 2–3 years
Who this is for
- Growers facing acute pest outbreaks who need fast results
- Indoor cultivators managing fungus gnats, whiteflies, or spider mites in high-humidity spaces
- Commercial and semi-professional operations requiring emergency containment
- Those with tight harvest windows (24-hour residue clearance is critical)
- Organic certified growers needing Soil Association–approved rapid intervention
- Anyone who's tried preventatives and now needs the emergency button
Our take
This is the insecticide you reach for when prevention failed and pests are winning. Pyrethrum 5EC does exactly one job — kills insects fast — and it does it properly. A 250ml bottle delivers exceptional value: 60+ litres of ready-to-use spray means one bottle covers serious ground without breaking the bank.
Not a preventative. Not a long-term management tool. An emergency intervention that works, clears quickly, and lets you harvest safely in 24 hours. Worth picking up if you grow indoors or in high-humidity conditions where outbreaks happen. Good time to stock while clearance lasts.
