Polyculture

An ancient practice that makes sense for today’s environmentally conscious gardener… Polyculture takes companion planting to the next level!

It is probably safe to say that most veggie gardeners practice companion planting in one way or another. It could be as basic as planting basil and tomatoes together, using nasturtiums as a trap crop for aphids or planting a border of marigolds to repel insects.

But did you know that you can take companion planting to another level? It is called polyculture, which means planting a mix of crops in a single space. It is an age-old practice that predates monoculture (single cropping) that was introduced with the advent of large-scale mechanised agriculture.

All the basics of companion planting apply in polyculture, such as using plants that have a beneficial effect on nearby plants, add nitrogen to the soil, as well as plants that either repel insects or attract pollinators and other beneficial insects.

But there is a difference. While companion planting will focus on a specific crop and companion plants that can be grown with it, polyculture looks at creating an eco-system in the same space by combining different plants that are of benefit to the whole.

The objective of polyculture is to make better use of space on a continuous basis, with greater biodiversity that leads to more stable yields.

An often-quoted example of polyculture is the ‘three sisters’ method of planting. It consists of maize that supports the climbing green beans, which in turn fix nitrogen in the soil and trailing squash (butternut or pumpkin) that provides shade for the roots of the maize and beans and supresses weeds.

Getting Started

Polyculture can be applied to any space; a single bed or a whole veggie garden (once you get the hang of it) and even vegetables grown in containers. It can be extended to the flower garden too.

The principle to keep in mind is that you are creating a beneficial eco-system of many components. Putting together a planting plan involves a lot more research into individual vegetables, how they benefit other vegetables (or not), their individual sun and nutrient requirements, root structures and root depths.

For instance, because of its high nitrogen requirements, maize should not be planted with tomatoes, that are equally nitrogen needy. Likewise, shallow rooted crops like lettuce and other salad greens will offer less competition to crops like potatoes that need more room for root development.

It will be trial and error, but that’s part of the challenge. Here are some pointers:

1. Start Small

Advice for polyculture practitioners is to start by planting three different veggies in the space where you would have planted one. Don’t be too enthusiastic. Plant less, so that plants have space to grow, which will produce a better harvest.

2. Integrate herbs and flowers for diversity

Once you have chosen your vegetables, select the appropriate herbs and flowers that either repel the pests or attract beneficial predators that are specific to the vegetables you are planting. Strong pest repelling herbs include chives, catnip, feverfew, catmint, coriander, pennyroyal, santolina and thyme. To attract beneficial insects, consider planting alyssum, creeping thyme, dill, echinacea, fennel and rudbeckia. Herbs like comfrey, borage and yarrow add nutrients to the soil while mustard acts as a biofumigant. Chamomile and salad burnet benefit nearby plants.

3. Be aware of good and bad companions

Choose vegetables that complement each other because there are some that do not thrive when planted together, such as tomatoes, eggplant and peppers because they are all targeted by the same pests. Also, beans should not be planted with any alliums which produce a chemical that kills the beneficial bacteria on bean roots, hindering their growth and preventing them from fixing nitrogen in the soil.

4. Maximise your space

Plant tall veggies (tomatoes, runner beans, eggplant) on the south side of the bed/garden where they won’t block the sun from lower growing veggies. Grow the shortest plants (carrots, beetroot) on the north side, with Swiss chard or bush squash in the middle.

Another strategy is to underplant taller veggies with lower growing veggies (beetroot, carrots, radishes, lettuce) that will benefit from the shade of taller plants.

Choose whichever planting pattern works for you. It could be rows (such as marigolds, carrots, chives and cabbage) or blocks (like square foot gardening) because this makes it easier to interplant beneficial flowers and herbs, or zigzag with taller veggies shading tender veggies from the sun.

READ MORE: Fabulous Companion Planting Combos

Veggies With Benefits

Here are some combinations you can try this spring and summer:

1. Beans, cucumber, carrots, sweet corn and marigolds

With their deeper roots, carrots loosen and improve soil texture, beans fix nitrogen and sweet corn can act as a support to cucumber. Marigolds both deter pests and attract beneficial insects as well as bees to their flowers.

2. Beetroot, cabbage, garlic, onions, lettuce and radishes

Beetroot adds minerals that benefit brassicas while garlic and onions repel pests. Lettuce and radishes have shallow roots that don’t compete with deeper rooted beetroot and cabbage.

3. Brinjals, beans, Swiss chard, oregano, marigolds

Brinjals shade Swiss chard from hot summer sun, while beans add nutrients to the soil and repel beetles. Oregano deters aphids, spider mites and other pests while its flowers attract bees. Marigolds attract many beneficial insects as well as deter pests, including root-knot nematodes.

4. Cabbage, sugar snap peas, beetroot, chives and dill

Sugar snap peas trained vertically can help shade cabbage from the summer heat, while beetroot draws nutrients up to the roots of the cabbage. Chives deter major cabbage pests like cabbage looper, cabbage worms, flea beetles and snails while dill attracts beneficial insects like lacewings that prey on aphids.

5. Garden peas, squash, radishes, nasturtiums and zinnias

Peas are an early cool season veggie. If planted with squash they will fix nitrogen but will be harvested by the time squash needs more space to grow. Radishes are also quick crops and will deter some bugs that prey on squash. Nasturtiums are a trap crop that attracts pests and the flowers and leaves are edible. Zinnias attract bees to pollinate the squash flowers. They, and nasturtiums can be planted as a border.

6. Sweet peppers, alyssum, basil, carrots and beetroot

Carrots and beetroot grow in the space under the peppers while beetroot benefits from the shade and carrot tops act as a living mulch. Alyssum attracts beneficial predators (ladybirds, lacewings, predatory wasps) that feed on aphids and other bugs while basil deters thrips and other pests.

7. Tomatoes, squash, lettuce, basil, chives and garlic

Tomatoes provide shade for lettuce and squash enjoys the same growing conditions while acting as a groundcover that shades the soil and reduces evaporation. Chives and basil act as pest-repellents and do not compete with the fruiting vegetables for nutrients.