Organic Pest Control That Actually Works!

Imagine gardening free of pests. It’s a nice thought but, alas, crop-chomping critters are the reality! Every garden faces pests – it’s part and parcel of a healthy garden. But that doesn’t mean we can’t fight back! Here’s how I do it…

Protect Plants With Barriers

The very simplest way to avoid pest problems is to simply cover your crops so nothing can get at them. Applying covers while the plants are still young should prevent them from ever being discovered by pests in the first place, so they’re protected right from the start.

For smaller insects use a fine-gauge mesh netting, also sold as insect barrier mesh or under brand names such as Enviromesh. This stuff is super fine, so there’s no way any flying insect can penetrate it. In most cases it’s just a matter of laying it over your beds – but take meticulous care to secure it at the edges so nothing can get in at the sides. I pin my mesh down with bricks, stones or boards to ensure this. Insect mesh is both breathable and permeable, allowing sun and rain to pass through and reach your veggies.

Insect mesh is my go-to cover during the growing season. It stops everything in its tracks – from the neighbourhood cats to flying insect pests, and I find it a lot more durable than horticultural fleece, which inevitably snag and tear. I deploy them to prevent leaf miners on my beetroot, stop carrot flies from landing on my carrots, and make sure the butterflies and moths responsible for caterpillar damage can get nowhere near my cabbage family crops.

Some plants benefit from being covered in their early days, with the covers removed to allow pollinators access later on. For instance, in North America squash bugs and squash vine borers can be a problem, and squash plants should be covered the moment they’re planted and kept covered until the plants are well-established and have begun flowering. At this point the covers need to be removed to let the pollinators in.

Other crop covers include wider gauge netting, which I use early in the season to keep pigeons off – they can decimate any brassicas left uncovered, believe me! Then as we move into summer, I swap to insect mesh.

You’ll also find butterfly netting which does as the name implies, and which is a finer gauge than the bird netting. It’s good stuff, but because the holes are clearly bigger than the insect mesh, it’s essential to support the netting on frames or hoops so that it’s kept up off your plants. Otherwise, if it touches the foliage there’s a chance that the butterflies could simply lay their eggs through the netting. For that reason I tend to use insect mesh almost exclusively during the summer months, because it really is an all-purpose cover.

Search and Destroy Pests

But we can’t cover everything all of the time. Some vegetables are just too tall or, like the squashes mentioned earlier, need to be out in the open so they can be pollinated. For these plants, vigilance is needed.

Early aphid infestations can be set back, buying you time til pest predators like ladybirds arrive, if you act fast the very moment you spot them. There are a few ways to deal with them – cut off affected foliage, squish small clusters between your finger and thumb, or just blast them off with your hose. Choose a setting on your spray gun that gives a strong jet of water then work over the foliage, holding leaves in one hand if necessary, to blast the aphids off onto the ground where they’ll likely perish.

Leaf miners can cause damage to beet leaves if the plants are left uncovered. The grubs devour their way through the leaf, creating tunnels. In a bad infestation they’ll join up to create a papery appearance. If the infestation isn’t too far along you can try to squash the leaf miners within the leaf, or just pinch off and remove the leaves, and then hopefully the leaves that grow to replace them will be leaf miner-free.

Slugs are often a nuisance in wet weather. The best way to deal with them is to proactively remove any you find. You can set up shady escapes for them, luring them beneath the cool of a grapefruit shell or a few strategically placed larger leaves like rhubarb. Then, from time to time, check under your shady refuges and collect up all the slugs that have congregated there.

Attract Beneficial Bugs

There’s a whole host of predatory insects that love to feed on soft-bodied pests: ladybugs, parasitic wasps, lacewings, hoverflies and minute pirate bugs, for example. You and can attract more of them to your garden by planting the flowers that many of them love.

Many herbs, allowed to flower, are a big pull for these sorts of beneficial bugs: dill, fennel, parsley, thyme, mint, basil, and oregano are all powerful plants to grow for this reason alone.

Then there are my go-to veggie garden flowers: poached egg plant (Limnanthes douglasii), calendula, sweet alyssum, and marigolds. Pop these fellas here and there to swell the ranks of your gardening allies.

It’s also worth attracting insect-eating birds to your garden. Grow a good mix of trees and shrubs for them to hang out and nest in.

Use Organic Pesticides (With Caution)

If you have an infestation that you’re determined to be rid of, the final option is to spray using an organic, natural pesticide. Just hearing the word ‘spray’ makes me wince, and I’d like to emphasise that this really should be the very last resort because any spray – even a ‘natural’ spray – is going to have potential side effects and may impact non-target species.

Suitable sprays include ones made with pure, cold-pressed neem oil or pyrethrin extract. In the US spinosad and Bt, which uses the bacteria Bacillus thuringiensis, are also available. Bt is especially effective against caterpillars (like those that munch on our brassicas), while others like spinosad or pyrethrin extract are broad-spectrum, which means they tackle a wide range of pests.

A very simple spray can be made at home by adding two teaspoons of washing-up liquid to two pints (one litre) of water. Give it a good shake then use this as a contact spray where infestations are very concentrated. Liquid soap isn’t great for the garden, so please, only use it in limited amounts as a kind of break-glass-in-case-of-emergency solution.

Whatever you decide to use, please, please avoid spraying during the day. Wait until after dusk, when pollinating insects and other beneficial bugs are less likely to be about. Spray on a still evening, so it doesn’t blow about, and be as targeted as you can.

I rarely use sprays, preferring other methods like barriers and beneficial bugs to dodge the worst of the pests. You could also plan to grow crops earlier or later than the main danger period for their pests, particularly if you have a longer growing season. For example, grow varieties of brassicas from autumn to late spring when butterflies aren’t around so much.

Plants Related to this Article

Beetroot Grow Guide

Beans (Broad) Grow Guide

Carrot Grow Guide

Bugs, Beneficial Insects and Plant Diseases

Leaf Miner Guide

Carrot Root Fly Guide

Cabbage White Butterfly Guide