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Hints & Tips

The Benefits of Companion Planting

As soon as you make the decision to grow your own veg, you will most likely start receiving all sorts of advice from people who have trialled and tested countless techniques. Terms like double digging, aphids, clubroot or Three Sisters will be thrown left, right and centre, and you will be left confused and bewildered with a load of tabs open on your computer and 10 books in your basket ready for check-out.

What many people agree on, however, is companion planting. It sounds like a very fluffy term, something someone would say in a Victorian setting, on a gentle Saturday afternoon with the sun shining into the Drawing Room. It is, in fact, a practice that humans have carried out for generations. Josie Jeffrey defines companion planting as the “establishment of two or more plant species planted in close proximity in order to culturally benefit each other by attracting or deterring pests, keeping the soil healthy and improving flavour”. While it does not necessarily completely solve a problem and does not protect plants 100%, learning about this technique will help when planning the crops you want to grow next season as well as to understand your surroundings and what plants need to grow.

What goes with what

As a general rule of thumb, alliums and herbs are your best friend. For example, you can mix mint, onion or garlic with carrots, tomatoes, cabbage, kale and radish. Broad beans planted near potatoes inhibit each other’s pests, whilst Nicotiana tabacum protects brassicas from cabbage white butterflies. However, hyssop is a better option for smaller spaces. Similarly, veg growers plant marigold around tomatoes to protect them from whitefly. At the same time, marigolds are destroyed by slugs, so it can act as a sacrificial plant (that’s another term you will become familiar with). Louise Riotte also recommends aromatic plants or those that have many blossoms such as thyme, chamomile, celery, dill, sage or rosemary.

Companions-in-the-garden1 harvest to table


Alliums in general, rosemary and sage act as a repellent to carrot fly. It is best to plant onion sets or garlic cloves as opposed to seed because they will already have a smell and will deter the carrot fly. If you sow carrots and onions at the same time, the trick will probably not work because they grow at different stages.

Veg such as lettuce or spinach benefit from having some shade during the day. Therefore, you can intersperse them with climbing beans or peas, whilst adding in some onions so rabbits are not tempted. While we’re on the topic of beans, when they and peas stop producing, let them die down and mix them into the soil. The roots have nodules which release nitrogen into the soil as they break down. Yarrow, on the other hand, accumulates phosphorous, calcium and silica; which can improve compost. It also attracts hoverflies and ladybirds.

Another beneficial plant that attracts pollinators is borage. Bees love it, and if you have strawberry plants try growing some borage nearby so the berries also benefit from the bees. These nectar-loving creatures are partial to coriander as well. The herb also has a reputation of repelling aphids.


For the greater good

There are some plants that are used in order to deter plants from feasting on our food, these are called sacrificial plants. We have touched on marigolds and slugs in the previous section; you can also grow lettuce around a bed to distract slugs from your precious crops. Nasturtiums are also a sacrificial plant as it helps with pollination, and pests love to munch on them.

At Sizergh Castle they intersperse kale with calendula because the latter attracts hover flies and other insects whose larvae eat on aphids. Another strategy to try is to sow radish around cucumbers and squashes to protect them from the cucumber beetle. Let them grow, flower and go to seed.

Rhubarb leaves that have been boiled in water and made into a spray can protect the cabbage family from clubroot if the drills have been watered before sowing.


Avoid, avoid, avoid

Cabbage white caterpillars can demolish a plant within days. Therefore, it is a good idea to keep brassicas separate; for example kale, cabbage and Brussel sprouts.

Do not plant potatoes or tomatoes near each other, and don’t plant a crop where you grew the other last season. Make sure you rotate your crops as they are from the same family and so will pass on blight to one another.

There are combinations that simply don’t work such as planting beans or peas with alliums, tomatoes with brassicas o potatoes with fennel.

There are many other combinations you can try, but these are some basic ones you can trial on your first year as an allotment holder. What combinations work well with your crops? Let us know through Twitter @Preloved. Companion planting also works well in the garden, you might find what you are looking for here!

Zoe Allison

Zoe Allison

Writer and expert