One bulb of garlic, three fresh chillies and a litre of water gets me roughly a litre of spray, enough for a proper going over of 15 to 20 plants. I’ve been making this in my kitchen for years and it costs less than a coffee. It won’t fix every pest problem in your patch, but for aphids, whitefly and small caterpillars it earns its place in the shed.
What You Need
I keep this simple. No blender attachment required, though it helps.
- 1 whole garlic bulb, all cloves peeled
- 2 to 4 fresh chillies (I use whatever’s hottest in the garden, birds eye if I’ve got them)
- 1 litre of water, plus a bit more for topping up
- 1 teaspoon of pure soap flakes or a few drops of unscented liquid soap (this is what makes it stick to leaves instead of beading off)
- A jar with a lid, a strainer, and a spray bottle
I don’t use dish detergent with added fragrance or degreaser. Some of those additives are harder on plant leaves than the garlic and chilli ever are.
The Method
- Blitz the garlic and chillies in a blender with a cup of the water until it’s a rough pulp. No blender? Crush it by hand, it just takes longer and your hands will smell for a day.
- Tip the pulp into a jar, add the rest of the water, and let it steep for 24 hours. I leave mine on the bench, not in the fridge.
- Strain through a cloth or fine sieve into your spray bottle. Squeeze the pulp hard, that’s where most of the active oils are.
- Stir in the soap flakes or liquid soap right before you spray, not before storage. It settles out otherwise.
I make a fresh batch every time I use it. It doesn’t keep well past a few days, even in the fridge, and the smell only gets more intense.
How to Use It
Test it on two or three leaves first and check back the next day. Garlic and chilli oils can scorch young or soft leaves, and I’ve burned a row of seedling lettuce learning that the hard way.
Spray in the early morning or evening, never in the middle of a hot day, and never on open flowers during the hours bees are working them. That’s usually mid morning through early afternoon here in Dayboro, but check what your local bees are doing before you spray anything blooming.
Cover the undersides of leaves, that’s where aphids and whitefly actually camp out. I reapply every 3 to 5 days while pest numbers are up, then back off once things settle down.
One climate note that matters: in the tropics and anywhere getting regular downpours, this washes off fast and you’ll be reapplying more like every 2 to 3 days after rain. In cool temperate and cold zones it holds on the leaf longer between waterings, so you can usually stretch the gap.
What It Actually Does
It’s a repellent and a mild contact irritant, not a poison. It won’t wipe out an established infestation overnight, and it does nothing for things like curl grubs or fungal problems. What I’ve found it genuinely good for is knocking back aphid numbers and putting off the moths that lay caterpillar eggs on my brassicas, before things get out of hand.
It’s not going to replace picking caterpillars off by hand or netting your seedlings. Think of it as one more thing in the routine, not a silver bullet.
I reckon it’s worth having a bottle of this on hand through spring and summer. It costs next to nothing, it’s made from stuff already in your kitchen, and making your own beats buying a spray with ingredients you can’t pronounce. The only real skill in it is remembering to steep it the night before you actually need it, which I still forget more often than I’d like to admit.
