How to Protect Your Brassicas from Cabbage White Butterflies and Caterpillars

They flutter in innocently enough, but don’t be fooled. If you’re growing cabbages, kale, sprouts or broccoli, you’ll know that the cabbage white butterfly is anything but a friendly visitor. One minute your brassicas are pristine, the next they’re full of holes and crawling with green munchers. Luckily, there are ways to fight back, and no pesticides required.

Netting: Your Number One Defence

We don’t grow brassicas without netting. Full stop. A fine mesh net (with holes no bigger than 7mm) keeps cabbage whites out while still letting in light and rain. It needs to be raised off the plants with hoops or frames so the butterflies can’t lay eggs through it. We secure the edges with bricks or bury them in soil, because a determined butterfly will find the smallest gap.

Egg Spotting and Removal

Despite our best efforts, the odd butterfly sometimes sneaks through. That’s why we make it a habit to check leaves regularly, especially the undersides. Cabbage white eggs are tiny, yellow, and laid in clusters. A quick squash or gentle scrape with a fingernail can save your brassicas from a caterpillar invasion later on.

Handpick Caterpillars

If you do find little green caterpillars chomping away, don’t panic. We just pluck them off and drop them into a tub of soapy water. It’s simple, chemical-free, and highly effective. Regular checks (every few days during peak butterfly season) keep numbers under control and damage to a minimum.

Grow Decoys and Diversions

Cabbage whites aren’t picky, so we sometimes plant sacrificial crops like nasturtiums or radish nearby. They’ll often lay their eggs on these instead, keeping the butterflies away from the main event. The nasturtiums also attract aphids, which then lure in beneficial predators like ladybirds. Win-win.

Camouflage with Companion Plants

Strong-smelling companions like sage, thyme, or dill can help confuse butterflies searching for brassicas. Interplanting herbs and flowers through the cabbage patch disrupts the visual cues butterflies use to find their target. Plus, it looks beautiful and boosts pollinator traffic.

Use Micromesh or Horticultural Fleece for Seedlings

Young brassicas are especially vulnerable. We cover seedlings from day one with micromesh or fleece until they’re strong enough to fend off a nibble or two. It also protects from flea beetles and early slug damage, giving plants a head start before the main pest season.

Keep Plants Healthy and Growing

Strong plants bounce back from pest damage more easily. We feed brassicas regularly with a balanced organic fertiliser and make sure they’re well-watered, especially in dry spells. Mulching helps retain moisture and keeps weeds (which can also host pests) under control.

Cabbage white butterflies and caterpillars might be a summer staple in British gardens, but that doesn’t mean they get to rule the veg patch. With a little planning, some netting, and a sharp eye, we can enjoy leafy, caterpillar-free brassicas all season long.