5 Top Tips For Garden Companion Planting
Companion planting is where two or more crops are grown together for the benefit of one, or all. The most successful combinations mirror nature. They can be an important part of planning a successful and productive garden.
The popular wisdom is that scented plants deter pests but experiments suggest this to be untrue. So lets start with some myth busting.
Companion Planting Myth Busting
It is believed that the smell of volatile oils from certain plants can discourage pests, making them excellent companion plants. Perhaps the most well known is the relationship between the tomato plant and the strong smelling French Marigold. This is said to deter whitefly, for instance.
The evidence from recent experiments has found this to be shaky. They surrounded cabbages with different companion plants (some strong smelling, some not) and found that the amount of scent had little to do with the amount of pest damage. Instead, it found that all the companion plant needed was green leaves. Pests are apparently drawn to plants with green leaves and land to assess suitability for egg laying. If they deem them not to be suitable then they fly off and don't make it to the cabbage to lay eggs. Plants with brown leaves did not protect the target plant as the assumption is that pests did not recognise these as egg laying sites. In our opinion the jury is still out on this because it could still be the scent of the plant that highlights them as an unsuitable place to lay eggs.
So that is the scientific evidence but if you talk to any experienced gardener they will certainly provide plenty of contrary anecdotal evidence. Many people seek companion planting for tomatoes and swear by growing tomatoes with basil and parsley. Useful for cooks as well as gardeners. And separating rows of brassicas with onions has always been popular. Does the strong scent of onions confuse cabbage pests? The only way to decide is to try it yourself.
No experiment can alter the fact that plants that attract pollinators are good to have around.
English Marigold (Calendula) can provide welcome splashes of colour in the kitchen garden. The added benefit is that they attract pollinators. Along with Yarrow (Achillea) and Hyssop they also attract hover flies. The hover flies will lay their eggs around these plants and when they hatch the larvae feast on aphids.
5 Top Tips for Companion Planting
1) Don't overcrowd
Just because the plants are together, doesn't mean they have to crowd each other. Plant the plants at the recommended distance for the vegetables being planted.
2) Avoid competition - use plants' differences
- Avoid competition for space. Plant shallow rooted plants with low leaf cover alongside deep rooted plants with broad leaf cover.
- Avoid competition over nutrients - grow heavy feeders that ned lots of nutrients with lighter feeders that need less.
- Take turns - mix slow-growing plants with fast-growing plants so they aren't competing for space or light.
3) Use a wide variety
Plant plants from different families. The reason for this is that crops will have their own, different pests and diseases. So by planting diverse plants you reduce the risk of a single type of pest arriving and destroying your whole harvest.
So rather than planting a whole bed of onions consider scattering them between different crops. It could protect them if worst comes to worst and pests infest your crop.
4) Think Structure
Some plants can give structure to a garden and help other plants as a result, Take for example the sunflower. This will attract pollinators to your garden but you can also grow climbing plants up its stem. So rather than wrestling with bamboo canes you can grow plants such as beans up sturdy sunflower stems. Find out how to grow Sunflowers here How to Grow Sunflowers
Another great companion planting example is the Three Sisters Planting method where corn gives a structure for beans to climb and pumpkins provide ground cover to suppress weeds and reduce water loss.
5) Create an eco system
Plant scented plants to deter pests and flowering plants to attract pollinators and natural predators such as ladybirds. This way your garden will be diverse and more resilient a a result.
Some plants are alleged to increase the production of essential oils in the plants next to them. This makes the plants' scent and taste stronger. One example is Chamomile also known as the 'plant doctor'. It is attractive and easy to grow so a worthwhile addition to any planting scheme. Another garden 'must have' is the super fragrant Lavender. This acts as a general insect repellent whilst still attracting bees to your plot.
Crops and their Companions
Different combinations work in different conditions, so experimentation and experience is the best guide. Below is our companion planting chart with some combinations of crops and their companions that work well in most situations. (Click on the vegetable name to find out exactly how to grow them)
- Asparagus: Tomatoes, Parsley, Basil
- Beans: Carrots, lettuce, parsley, spinach
- Beetroot: Onions, cabbages
- Cabbages: Celery, mint, thyme, onions, nasturtiums
- Carrots: Peas, radish, chives, onion, leek
- Courgette: Nasturtiums
- Lettuce: Strawberry, beetroot, radish
- Onions: Carrots, beetroot, chamomile, courgette
- Parsnip: Garlic
- Peas: Potatoes, radish, carrot
- Spinach: Strawberry
- Tomatoes: Celery, basil, marigolds, foxglove
Whether you believe that the scent of companion plants does something magical or not remember that nature abhors a vacuum so if you don't plant something between your crops weeds will take over so it is certainly worth experimenting.
Check out Haxnicks Sustainable Gardening products over on our YouTube channel here Haxnicks and Sustainability
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