If you’ve ever walked out into your winter garden feeling proud of your beautiful broccoli, cabbage, or kale… only to discover holes everywhere and little green caterpillars having the feast of their lives — welcome to brassica season.  Brassicas are some of the most rewarding winter vegetables to grow, but they are also magnets for pests. Aphids, cabbage moths, caterpillars, snails, slugs, and even fungal diseases can quickly become a problem if we don’t create balance in the garden.

This is where companion planting becomes one of the most powerful tools in an organic veggie garden. And one of the smartest companion planting methods of all?
Trap crops.

What Is Companion Planting?

Companion planting is simply the practice of growing certain plants together to help each other thrive.

Some plants repel pests,  attract beneficial insects,  improve soil health,  provide shade or ground cover,  confuse pests with strong smells  or act as sacrificial plants to protect your main crop. Nature was never designed to grow vegetables in neat single rows of one crop. Monoculture makes it very easy for pests to find exactly what they’re looking for. The more diversity we create in the garden, the more balanced the ecosystem becomes.

What Is a Trap Crop?

A trap crop is a plant that pests prefer over your main crop. Instead of trying to completely eliminate pests from your garden (which is almost impossible), trap crops work by attracting pests away from the plants you actually want to harvest. Think of it like giving the pests a distraction.

The pest finds the trap crop first, settles there, lays eggs there, and often leaves your main brassicas alone or at least reduces the pressure dramatically. This method works incredibly well in natural gardens because it works with nature instead of against it.

Why Trap Crops Work So Well for Brassicas

Brassicas have a very strong scent profile that pests are naturally drawn to. Cabbage moths can smell brassicas from surprisingly far away, and once they find your plants, they quickly begin laying eggs underneath the leaves. Those tiny yellow eggs soon become hungry caterpillars. But certain plants are even MORE attractive to these pests than your actual crops.

That’s where trap crops become useful.

Best Trap Crops for Brassicas

• Nasturtiums

This is probably one of my favourite trap crops in the veggie garden.

Nasturtiums attract aphids, cabbage moths, caterpillars and  flea beetles. Instead of your broccoli becoming covered in aphids, you’ll often find the nasturtiums taking the hit first. They also spill beautifully through beds and attract pollinators at the same time.

• Mustard

Mustard is extremely attractive to flea beetles and certain brassica pests. Many gardeners plant mustard slightly away from their main brassica beds to lure pests away from cabbage and cauliflower. The bonus? Mustard grows quickly and improves biodiversity in the garden.

• Radishes

Radishes can also act as sacrificial plants for flea beetles. They germinate quickly and often become the first target, protecting slower-growing brassicas nearby.

How to Implement Trap Crops in Your Garden

This is where many people get confused. A trap crop does NOT work well if planted too far away from your main crops. The goal is to intercept the pest BEFORE it reaches your brassicas.

Here’s what works well:

• Plant Trap Crops Around the Edges

Surround your brassica beds with trap crops like nasturtiums or mustard. Think of it like building a protective border around your vegetables.

• Plant Earlier Than Your Brassicas

This is important. You want the trap crop already established and attractive BEFORE pest pressure starts increasing. If the trap crop is too small, pests may still choose your cabbage instead.

• Don’t Remove Every Pest Immediately

This sounds strange, but remember, the trap crop is doing its job. If you instantly destroy every aphid on the nasturtiums, the pests simply move back to your brassicas. Instead, monitor the balance carefully.

• Manage the Trap Crop

Sometimes the trap crop becomes heavily infested. At this point you can prune affected leaves, spray organically if needed,  remove heavily damaged plants or allow beneficial insects to move in naturally. Often you’ll find ladybirds arriving shortly after aphids appear. Nature starts balancing itself surprisingly quickly when diversity exists.

Companion Plants That Help Brassicas

Trap crops are only one piece of the puzzle. Other companion plants can help support your brassicas too.

• Dill –  Attracts parasitic wasps and beneficial insects that prey on caterpillars.
• Coriander – When flowering, it attracts hoverflies and predator insects.
• Garlic and Spring Onions – Strong smells may help confuse pests and reduce aphid pressure.
• Marigolds – Help attract beneficial insects and improve overall biodiversity.
• African Wormwood – One of my personal favourites in the garden. Many gardeners use it around beds because of its strong scent and traditional pest-deterring reputation.

The Truth About Companion Planting

Companion planting is not magic. It won’t make your garden completely pest-free. You will still find caterpillars. You will still lose a leaf here and there. And yes… sometimes the snails still win. But what companion planting DOES do is create balance. Instead of massive outbreaks, you often get manageable problems. And over time, your garden slowly starts functioning more like an ecosystem instead of a battle zone.

One of the biggest lessons I’ve learned in the garden is this: A healthy garden is not about eliminating every insect. It’s about creating balance. The moment we stop trying to sterilise the garden and start working with nature, things begin changing. Trap crops are one of the simplest, cheapest, and most effective ways to protect brassica

Tash en die Familie

For our members, don’t forget that we have loads of free resources available under our Downloads page to help you succeed in the veggie garden. From seasonal planting guides and pest management help, to soil health, companion planting, composting, and practical step-by-step growing advice — we’ve created these resources to make gardening simpler, more enjoyable, and far less overwhelming.

Sometimes a small bit of guidance at the right time can save an entire crop  Find it here