Companion planting

Companion Planting is a system where two or more plants are grown in close proximity, in order to provide some form of protection to one or all of them. It is a form of polyculture. Polyculture includes crop rotation, companion planting and the use of beneficial weeds.

Benefits could be to act as a deterrent or a decoy for pests and diseases. Some plants produce chemicals from their leaves which can deter certain pests, i.e. African Marigolds produce a substance called thiopene which repels the tiny slugs that live in the soil, therefore making it a good companion for root crops.

Another good example of this would be the carrot and carrot fly. The carrot fly is attracted to the smell of the carrots especially when the crop is being thinned, the scent is strongest when leaves are crushed. To stop the carrot, fly from finding your carrots place a plant with a stronger smell near to the carrots. There are various plants that can help with this. Onions are a good one to try as the strong odour they give off will help mask the scent of the carrots.
Planting taller plants around your crops can provide shelter and also creates a micro-climate which can protect from pests. Helpful insects can be encouraged by planting something nearby which they use for food, i.e. hoverflies love nectar but their larvae feed on aphids, so putting plants rich in nectar nearby will attract them.

Trap crops also work well. Black aphids love nasturtiums more than anything. If you have trouble with aphids on your bean plants, then you can plant nasturtiums nearby and then pull them up when they are full of aphids. 

Please find below in alphabetical order of plants and their good and bad companions we hope you find it useful.

Plant Name - Asparagus
Best Friends - Can stop tiny nematodes from attacking the roots of tomato plants.
Worst Enemies -

Plant Name - Aubergine
Best Friends - Runner beans, Dwarf beans, Spinach.
Worst Enemies -

Plant Name - Basil
Best Friends - Pepper, Tomato, Marigold
Worst Enemies -

Plant Name - Beans
Best Friends - rosemary, peas, cucumbers, carrots, chives, radishes, lettuce.
Worst Enemies - onion or fennel.

Plant Name - Beetroot
Best Friends - Beans, Cabbage, Onion, Sage.
Worst enemies - Mustard

Plant Name - Brassica's (Cabbage Family)
Best Friends - Bush Beans, Beets, Celery, Onions, Tomato, Marigold, Nasturtium, Sage, Rosemary.
Worst Enemies - Strawberry and Caraway

Plant Name - Carrots
Best Friends - Bush Beans, Pole Beans, Lettuce, Onion, Leeks, Peas, Radish, Tomato, Sage grow well with chives, rosemary, parsley and tomatoes. (Onions are good at repelling carrot fly due to the smell).
Worst Enemies - Dill

Plant Name - Celery
Best Friends - Dwarf Beans, Cabbage, Onion, Spinach, Tomato
Worst Enemies -

Plant Name - Cucumbers
Best Friends - Beans, sweetcorn, Lettuce, Onions, Peas, Radish, Marigold, Nasturtium, Savoury
Worst Enemies - No strong smelling herbs

Plant Name - Lettuce
Best Friends - Carrots, Cucumbers, Onion, Radish, Beans, Chervil and Strawberries
Worst Enemies -

Plant Name - Melon
Best Friends - sweetcorn, Nasturtium, Radish.
Worst Enemies -

Plant Name - Nasturtiums
Best Friends - Cucumber and lettuce
Worst Enemies -

Plant Name - Onion
Best Friends - Beetroot, Cabbage, Carrots, Celery, Cucumber, Lettuce, Pepper, Squash, Strawberries, Tomato, Savoury 
Worst Enemies - Peas and Beans

Plant Name - Parsley
Best Friends - Tomato
Worst Enemies -

Plant Name - Peas
Best Friends - Dwarf beans, Runner Beans, Carrots, Sweetcorn Cucumber, Radish, Turnips. lettuce, Turnips.
Worst Enemies - Onion and Garlic

Plant Name - Pepper
Best Friends - Onion
Worst Enemies -

Plant Name - Radish
Best Friends - Beans, Carrots, Cucumber, Lettuce, Melons, Peas, Squash beetroot, spinach, parsnips, beans.
Worst Enemies - Hyssop, cabbage, Cauliflower, Brussel sprouts, broccoli, or turnips.

Plant Name - Runner Beans
Best Friends - Carrots, Corn Cucumber, Aubergine, Lettuce, Pea, Radish
Worst Enemies - Onion

Plant Name - Spinach
Best Friends - Celery, Aubergine, Cauliflower.
Worst Enemies -

Plant Name - Squash
Best Friends - Sweetcorn, Onion, Radish.
Worst Enemies -

Plant Name - Strawberry
Best Friends - Beans, Lettuce, Onion, Spinach.
Worst Enemies - Cabbage

Plant Name - Sweetcorn
Best Friends - Runner beans, Cucumber, Melons, Peas, Squash and Potaotes.
Worst Enemies - Tomato

Plant Name - Tomato
Best Friends - Cabbage, Carrots, Celery, Onion, Mint.
Worst Enemies - Sweetcorn, cabbage, Cauliflower and Fennel, French Marigold.

Make sure you plant your companions at the same time as your edible crops to prevent pests from getting a hold.

Very useful Herbs

Bay Leaf - The leaves of this pungent plant can be dried along with other strong herbs and sprinkled around the garden as a natural insecticide.

Borage - A self-seeding annual, borage makes a good companion plant for tomatoes, squash and strawberries. Also a good plant for attracting beneficial insects like bees. An excellent mulch, soil conditioner and a good addition to your compost heap it is rich in minerals like potassium, calcium and mineral salts.

Chervil - A good companion for radishes and keeping aphids away also known to deter slugs.

Chives - Onion scent protects chrysanthemums, sunflowers and tomatoes from aphids.

Comfrey - This plant was traditionally used for medical purposes, it is rich in potassium, calcium and phosphorous. A good place to look for slugs as they like to hide amongst its foliage.

Coriander -  Helps to repel aphids and spider mite.

Dill -  Attracts beneficial insects like hoverflies and predatory wasps that love to eat aphids and a good chum for your lettuce.

Garlic - The Strong smell helps to deters aphids and is a good companion for roses. has been known to ward off snails, carrot fly and codling moth.

Hyssop - A member of the mint family, hyssop makes a good companion for cabbages and grapes, will fend off attacks from flea beetles and codling moths. Do not plant it near radishes. Excellent for attracting bees.

Lavender - A beautifully scented plant and a must for every garden or allotment, repels flea beetle and moths. Makes an excellent food source for many beneficial nectar loving insects.

Lemon Balm -  When crushed this plant gives off a heavenly citronella like scent which makes many bugs dislike it. Can be invasive so best grown in a pot.

Mint - A very useful plant to have in the garden, it is known to deter many insects such as flea beetles, ants, aphids and cabbage moths. Also effective in deterring mice. Can be used as a mulch around your brassica's. A very invasive perennial so best grown in a pot.

Oregano - Makes a good companion plant for members of the brassica family and good for repelling the dreaded cabbage white butterfly.

Parsley - Good companion for onions, tomatoes, carrots and asparagus. It's flowers a great for attracting insects like hoverflies and bees. Don't plant near mint as they don't get on!

Rosemary - Makes a good companion for beans, cabbages and carrots. Can keep carrot flies and cabbage moths at bay.

Sage - A good companion for brassica's and carrots will deter cabbage moth, carrot fly and flea beetle. The flowering plant attracts many beneficial insects.

Tarragon - Can be planted throughout the garden, disliked by many pests.

Yarrow - A strong smelling plant which attracts many beneficial insects such as ladybirds and hoverflies. It is known to give a boost to other plants and accumulates phosphorous, calcium and silica, and is great added to your compost heap.