Insecticidal soap spray

How it works

Soap strips the waxy waterproof coat off soft-bodied insects, so they dry out within minutes. It is purely physical - insects cannot become resistant to drowning.

Recipe

10-20 ml pure potassium soft soap per 1 litre of water (start at 10 ml on tender leaves). Use soft or rain water: hard water reacts with the soap and cuts the effect. Mix fresh each time - it does not keep.

How to apply

Soak the UNDERSIDES of leaves until dripping - it only kills what it physically wets, and leaves nothing behind. Repeat every 5-7 days for 3 applications to catch newly hatched young. Early morning or evening.

Targets — pests

Aphids, Whitefly, Spider mite, Mealybug, Thrips, Scale (crawlers)

Targets — diseases

Not recorded — the field is blank rather than guessed.

Supplies: Potassium soft soap, 5 L pressure sprayer, Measuring syringe

Days to harvest after spraying: 0

Best months: not recorded

Cautions

Never spray in sun or above 28 C - the leaf will scorch. Test one leaf first on brassicas, sweet peas and young seedlings. Never use dish detergent: the degreasers and perfumes burn foliage.

The thing people get wrong

Most people spray the top of the leaf and wonder why it failed. Aphids and whitefly live underneath. Turn the leaf over, or do not bother spraying at all.