All Together Now: The perks of companion planting

When you are first starting out in a vegetable garden, it can be a little intimidating when trying to decide what to put where. Your plot is like a blank page – although it can be scary to start creating, once you get going you’ll realise that the possibilities are limitless and, so too, is your imagination.

Every winter I spend my time designing my plot for the upcoming planting year. Along with growing factors like sunlight and soil type, the main thing I like to keep in mind is how can I produce the most yield while using the least amount of pesticides or unnatural fertilisation methods. This is where the magic of companion planting comes into play!

Companion planting can seem a bit tricky to understand but, with a little knowledge and some planning, you’ll soon realise just how achievable this method of planting can be. The whole idea behind it is to group complimentary vegetables, fruits, herbs, and flowers together to naturally encourage eco-friendly methods of pest control and better crop rotation for healthy soil production. All too often, the health of the soil gets overlooked and instead we tend to focus on plant health, but it’s really simple when you break it down – healthy soil = healthy plants.

To best understand companion planting, let’s look at the simple carrot. It is frequently seen on a plate and is a staple purchase of any trip to the shops, yet the complexities of growing this simple veg is often overlooked. Carrots do not like soil that has been manured within the previous 6 months or so of planting, it needs a rock free planting site, and it is one of the few veg that will not benefit from a good dose of nitrogen (which is often the primary ingredient in many garden fertilisers). They are also notoriously tricky to grow because of the dreaded carrot fly – tiny insects who lay their larvae at the base of carrots who, after hatching, will bore holes through carrots. If you’ve ever grown a carrot with small black holes burrowed through the flesh, you definitely have carrot fly.

In order to appease carrots, gardeners often have to make special growing conditions to get these roots to develop as well as possible, particularly to avoid the dreaded carrot fly as much as possible. The most common advice is to grow carrots in raised beds about 1 metre (3 ft) off the ground, to sow thinly in order to avoid attracting carrot fly during the thinning process (they hone in on the smell), and to cover with insect proof mesh. Last year I was able to grow a fairly respectable crop of carrots – with approximately 10% affected by carrot fly – which is saying a lot considering they were grown at ground level and with no protective fleece. Part of what I attribute to this success is from the perks of companion planting. Interspersed between my rows of carrots were rows of onions, leeks, and marigolds – three plants whose strong fragrance is said to repel and confuse carrot fly.

Other relationships that best exemplify companion planting is the ‘three sister’s’, attributed to the genius of Native American growers. In this example, the ‘three sister’s’ are squash, sweetcorn, and beans. The idea was that you would plant climbing beans and ground roaming squashes amongst the stalks of sweetcorn. The beans would introduce high amounts of nitrogen into the soil – directly benefiting the hungry squashes and sweetcorn – and in return the beans would climb the sweetcorn for support. The squashes would tangle themselves on the ground around the base of the beans and sweetcorn, suppressing any weeds which could have sapped vital water, sunlight, and nutrients from the other plants. In this way, Native Americans were able to use one advantage from each vegetable in order to support and nurture the growth of another – and that is the beauty behind companion planting.

Just as some plants can be beneficial to others, so can they be combative. For example, it is important to never plant potatoes with squashes or any similar fruiting plant. Potatoes can often get blight – a fungus that appears as black spots on the leaves and can often ruin crops (think the Irish Potato Famine) – which is very easily spread to squashes. While some potatoes with blight can still be salvaged, blight tends to rots squash plants from the inside out. It is also said that you shouldn’t plant peas next to anything in the allium family (like onions, shallots, garlic, or gladioli) because they can stunt the growth of peas.

Now, this isn’t to say that if you break some of the rules or put peas and onions several feet away from each other that nothing will grow – in fact, this year I have peas and leeks growing quite happily only a few feet away from each other. It just to say that they do not necessarily compliment or assist each other or can possibly make it more difficult to have the best harvest. Even though I try to rigorously follow the rules of companion planting, there are many times when even I have to bend the rules occasionally to allow for the best use of space. Which is why I try to instead think of companion planting as a system for encouraging good bedding relationships rather than an absolute rule, even if that means that sometimes you have to plant some non-companion plants a bit closer together.

The below table is a good reference for what works best together and what to avoid, if you can help it.

In particular, I want to give a shout out to four rock stars in companion planting: lavender, marigolds, nasturtiums, and sage. Not only do these plants encourage beneficial insects like bees, butterflies, and ladybirds to your plot, they also make gorgeous additions to the dinner table!

Lavender is like an all day buffet for bees – I have four large lavender bushes in my home garden and several more in the plot. Without fail, bees are always happily buzzing around and gorging themselves on the bright purple and white flowers of my lavender bushes. Not only do the bees like it, but it also brings a delicious flavour to baked goods like cakes and scones or stewed with peppermint leaves for a relaxing tea. The scent is amazing when left to steep in a hot bath or packed in mesh sacks and put in your clothes drawers. If you don’t have lavender in your garden, drop everything you are doing and go get some – well, keeping within the lockdown restrictions, obviously!

The next on the list are marigolds and nasturtiums. These brightly coloured and strongly scented blooms may not be everyone’s favourite scent, but they make wonderful additions to any vegetable garden because of their ability to repel vegetable-loving pests and attract beneficial insects to your site. Marigolds attract vital ladybirds, hoverflies, and pest eating mini-wasps as well as attract important pollinators like bees. They are also able to repel parasitic nematodes, bean beetles, and most slugs, so it’s a good idea to plant these next to your more delicate crops like lettuces, climbing beans, and brassicas.

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Nasturtiums do an equally important job in your garden. Their scent helps to deter destructive insects like whiteflies, squash bugs, aphids, and cucumber beetles. Along with marigolds, nasturtium flowers are edible and make a lovely addition to salads. They also provide a gorgeous, bright pop of colour to make your beds really stand out. Feel free to grow as many marigolds and nasturtiums as you can and plant them liberally in your beds.

Sage – in addition to being my favourite herb for its delicious flavouring of soups, stuffings, and roast dishes – also acts as a beneficial plant for vegetable gardens. Not only does it smell beautiful in the summer sun but it makes a wonderful companion plant for French beans, strawberries, carrots, and brassicas. As sage likes to be in a much looser soil, I would recommend adding it to the edge of your vegetable beds in well-prepared ground or in pots stacked neatly alongside the rows. Sage, along with rosemary, also create beautifully delicate purple flowers that are irresistible to pollinators and make lovely addition to bouquets. In fact, my wedding bouquet had stalks of sage and rosemary mixed in with the white roses, anemones, and eryngium for a romantic and whimsical feel.

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As with everything in your garden, have fun and feel free to experiment. The best way to learn is to try it yourself, maybe fail a few times, and develop a system that works best for you and your plot.

Happy (companion) planting!