Companion planting combinations to boost vegetable yields

Companion planting is one of those subjects where the good information and the folklore are sitting right next to each other, and nobody ever labels which is which. Some of these pairings genuinely work and some of them are just something people repeat. So here are the ones worth your bed space, with what each one is actually doing, and a short list at the end of the claims that do not stand up.

Tomatoes and basil

They're both warm season crops, they both go in October to December once the frost risk has passed, and they want the same soil and the same watering, which is half of why this pairing works at all.

Basil is strongly aromatic and it does seem to make life harder for whitefly and aphids around the tomatoes, and the tomato plant gives the basil some shade through the worst of the afternoon so it doesn't bolt as fast. The claim that basil makes the tomato taste sweeter gets repeated everywhere and there is nothing much behind it. Grow them together anyway, because everything else about the pairing stacks up.

Carrots and spring onions

Carrot fly larvae tunnel through the root and you don't find out until you pull it. The strong onion smell makes it harder for the fly to locate the carrots, so a row of spring onions in among them is genuinely worth doing.

Carrots take a sowing from August right through to April here, and spring onions will go in across most of the year, so this is an easy one to set up.

Corn, beans and pumpkin

This is the Three Sisters planting, and it comes from Native American growing rather than from anywhere local, so it is worth naming properly rather than leaving it vague.

The mechanism is real. Beans fix nitrogen in the soil, the corn gives the climbing beans something to grow up, and the pumpkin runs along the ground underneath with big leaves that shade the soil and keep the weeds down. All three are warm season, so all three go in October to December, and you need a decent patch of ground because the pumpkin will run a long way.

Lettuce and radish

Radish is up and eaten in about a month while the lettuce is still getting going, so you get two crops out of one piece of bed. The radish roots break the surface up a bit as they swell, and pulling them leaves gaps for the lettuce to spread into.

Both take a sowing from February through to November, dodging the worst of the summer heat, which makes them the easiest pair on this page to get right.

Marigolds, more or less anywhere

French marigolds suppress root-knot nematodes in the soil, and that one is properly established rather than folklore. They also pull hoverflies in, and hoverfly larvae eat aphids. Put them through the tomatoes, the beans or the cucumbers and they earn their space.

What they do not do is repel rabbits, whatever you read. If you have rabbits, you need a fence.

Pairings to keep apart

• Tomatoes and potatoes. Same family, same diseases, and planting them together doubles your chances of losing both.
• Carrots and dill. Dill left to flower will cross-attract the same pests, and a big dill plant will shade out a carrot row.
• Anything from the same family, two years running. This matters more than any of the pairings above. Move the brassicas, move the tomatoes, move the onions, and you will avoid most of the soil-borne disease that ruins a patch.

Where to start

Pick one pairing and try it. Tomatoes and basil is the easiest because you were probably growing both anyway, and it costs you nothing to put them in the same bed.

Companion planting is a useful nudge and it is not a force field. It sits on top of decent soil, sensible watering and moving your crops around, and none of those get skipped because you planted a marigold.

Shop related products

• D.T. Brown Sweet Basil Seed Pack. Goes in with the tomatoes.
• D.T Brown Tomato Grosse Lisse Seed Pack. The reliable full-sized tomato here.
• D.T. Brown Carrot All Season Seed Pack. Long sowing window, so it suits most beds.
• D.T Brown Marigold Seed Pack. Cheap, tough and they do a real job in the soil.

Did you know we also carry spring onion, radish in three varieties, sweet corn in four, climbing beans and pumpkin seed in store, and none of those are on the website. Give us a ring on (08) 8536 4333 or come and have a look at the seed stand.

The garden range is on the website, and the garden centre carries a good deal more than the site does.

More from the garden

• Why your tomatoes are struggling, and how to fix it
• Growing zucchini, and when to sow it
• The native bees that pollinate a vegetable patch

Still learning, still planting the pumpkin somewhere it immediately outgrows. Candeece.

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