Companion planting is the technique of selecting ‘helpful’ plants to support your crops. By planning your patch in this way, you can attract predatory insects and deter the unhelpful ones. If you also intercrop your plants, you’ll be able to maximise production on the smallest space.
Companion Planting to Fend off Pests
For decades, allotment gardeners have grown marigolds beneath their tomatoes and nasturtiums along the edges of brassica beds. Careful selection of companion plants can offer your valuable crops extra protection against pests. Carrot fly and aphids, for instance, are deterred by the strong smells of sage, leeks and garlic; so roses and carrots can be protected in this way. Hoverflies – the natural predators of aphids – are attracted by flowering annuals such as dill and coriander, so these are two more options for protecting your lettuce and tomatoes.
Not every insect is a pest, of course. It pays to encourage some sorts onto your vegetable patch. The best way of doing this is by creating a good supply of nectar and pollen. The beneficial insects – such as ground beetles, ladybirds, hoverflies, lacewings and wasps (except where fruit is being grown) – will be attracted to nectar‐rich flowers. You can grow edible marigolds, flowering fennel and thyme. If you have space, add some cornflowers, nigella damascena, and sweet peas all of which make lovely cut flowers as well as attracting insects.
Intercropping for Maximum Production
Whether you have a square yard or an acre, intercropping is a great way to get the most from your soil. It’s particularly useful for those with smaller vegetable patches.
Pairings are made between types of vegetable that have different growing habits – for example, a low‐growing squash plant won’t hinder a tall sweetcorn plant. You wouldn’t intercrop two varieties that have similar growing habits (such as squash and courgettes). It’s also usual to choose two varieties with different maturing periods, so that you can crop one unobtrusively before the second needs to be pulled. This means intercropping a fast‐maturing vegetable (like corn salad) with a slow‐growing vegetable (like celeriac).
Intercropping is usually done in rows – one row of one variety, one row of another. However, you can mix the seed and sow mixed rows if you choose the varieties carefully. For example, it’s a good idea to mix carrot seed with annual flower seed (like cornflower or nigella). This helps to repel carrot fly. You can also sow mixtures of slow and fast‐growing roots, such as leek/spring onion and parsnip/radish. You’ll be able to pull the fast‐growing spring onion and radish before the larger roots need the room.
Saladini seed mixtures are very useful for intercropping. Thanks to their quick growth, they can be sown between or around most varieties of vegetable. Slow growing brassicas, root vegetables, and shallots can be surrounded or intersown with saladini seeds. The salad leaves will help to prevent weed growth and preserve soil moisture, and can be cut a long time before the main crop requires the space.
Other fast‐maturing varieties for intercropping include spring peas (intercrop these with winter brassicas), lettuces, spring onions, pak choi, beetroot, and spinach. Plant these between or around slow‐growing crops such as brassicas, Swiss chard, carrots, leeks, and turnips.