Planting guide

Companion planting
Companion planting is a framework that can help us get the most compatible mix of crops which will, hopefully, result in improved quality of produce. By considering the compatibility of the plants we choose, we can make the most of the available space and resources in the garden.

Many of the combinations are based on “folk-lore”, inherited by generations of gardeners, and we really don’t know how they work or if in fact they really do. However, science is starting to identify reasons for these beneficial interactions, such as the chemicals excreted by plant roots. Feel free to conduct your own experiments and see if you think there is a benefit in certain combinations. The most positive outcome of companion planting is that it creates biodiversity in the garden and that on its own is beneficial to all your plants.

Good companions

Some combinations of crops seem to benefit each other. The reasons for this may be straightforward, such as two plants requiring different nutrients and thus not competing with each other, or one repelling a pest of the other. Other reasons may be more mysterious, as in the case of yarrow (known as the “physician plant”) which appears to improve the general health of those around it.

Often these crops just seem to work well together. We’ve taken it for granted that these combinations of plants have been tried and tested by generations before us and if they work, that’s great for us. If you try a combination and feel that it is not proving beneficial, then by all means try a different companion.

Some combinations are used because they make common sense. For example, plants that have roots close to the surface, such as lettuce, can be planted next to those that send their roots deeper, like tomatoes. These each get their nutrients from different levels within the soil. Another example of such compatibility is using taller-growing plants to provide shade for other plants, such as planting sunflowers to shade cucumbers.

Another consideration when planting different types of plants together is how their root system grows. Plants which have roots close to the surface should be planted next to those which have deeper roots. Planting vegetables with different root-growth habits together will utilise nutrients from varying soil depths and thus reduce competition between the plants.
Yarrow is known as the “physician plant” and is a good general companion
Broad bean flowers

Good Companions list

Apples – Chives (protect against apple scab) / Foxgloves / Garlic / Nasturtiums / Wallflowers

Apricots – Basil / Southernwood / Tansy

Asparagus – Basil / Parsley/ Tomatoes                           

Beans – Beetroot (with dwarf beans) / Cabbage / Carrots / Cauliflower / Celery / Cucumbers / Lettuce / Peas / Parsley / Potatoes (with broad and dwarf beans) / Spinach / Sweetcorn  

  • Dwarf beans in alternating rows with beetroot and potato will increase plant health and crop yield.
  • Runner beans love family and pet hair. Place vacuum contents and sodden newspapers in a trench before planting.

Beetroot – Cabbage / Dwarf beans / Kohlrabi / Lettuce / Onions / Silverbeet

Cabbages (brassicas) – Beans / Beetroot / Celery / Chamomile / Dill / Mint / Onions / Oregano / Potatoes / Rosemary / Sage (improves plant quality, flavour and digestive qualities) / Thyme

  • Short sticks of rhubarb throughout the patch will protect against club root

Carrots – Chives / Leeks (sow together- carrots will be ready for harvest before leeks, which will have protected carrots against carrot fly) / Lettuce / Onions (alternate rows as carrots will deter onion fly and onions deter carrot fly) / Peas (plant carrots on the side that receives the most sun) / Radishes / Rosemary / Sage / Wormwood (the strong scents will deter carrot fly)

Cauliflower – Beans / Celery (will deter cabbage white butterfly) / Sage

Celery – Beans / Cabbage / Cauliflower / Dill / Leeks (plant in alternating rows- both like pig manure) / Tomatoes

Citrus- Guava (repels psyllids, protecting the citrus against the virus carried by psyllids)

Cucumbers – Beans / Celery / Chives / Lettuce / Marjoram / Oregano / Potatoes / Radishes (repel cucumber beetle) / Savoy cabbage / Sunflowers (will shade cucumbers) / Sweetcorn

Eggplant – Beans / Potatoes

Garlic – Apples / Apricots / Peaches / Roses 

Grapes – Basil / Beans / Geraniums / Hyssop / Mulberries / Mustard greens / Peas / Tansy

Kohlrabi – Beetroot / Onions

Leeks – Carrots (grow in alternating rows as they have a mutual protection for each other) / Celery (deters cabbage white butterfly- grow in alternating rows as both like pig or goat manure and compost, and benefit from added potassium)

Lettuce – Beetroot / Cabbage / Carrots / Chervil / Marigolds (French or African; their scent repels many insects) / Onions / Radish (lettuce thrives when radish is present, and protects radish against flea beetle) / Strawberries

  • Wood ash scattered around will protect against insects

Onions (alliums) – Beetroot / Carrots (grow in alternating rows as carrot will protect against onion fly) / Lettuce / Fruit trees / Brassicas (cabbage family) / Nightshades (solanacae family) / Strawberries / Celery / Parsley and other herbs / Passionfruit / Cucumbers / Marigolds.
(*) Alliums confuse pests with their strong odour, masking the smell of other plants. They also help to prevent fungal diseases such as verticillium wilt in tomatoes and deter pest such as slugs, red spider mite and aphids.

Parsnips – Beans/ Garlic / Peas / Peppers / Potatoes / Radish

Peas – Beans / Carrots (roots excrete a chemical that encourages pea plant growth) / Cucumber / Onions / Potatoes / Radishes / Sweetcorn / Turnips

  • Peas grow well with most vegetables, and dwarf varieties are great as they don’t block as much sun from their companions. Taller varieties of pea will shade lower-growing vegetables such as lettuce.

Potatoes – Beans (help to deter Colorado beetle) / Broad beans / Cabbage / Horseradish and nettles will also protect crop against pest insects / Marigolds (repel nematodes and Colorado beetle) / Nasturtiums / Peas / Sweetcorn

Pumpkins – Beans / Cabbage / Horseradish / Marigolds / Peas / Sweetcorn

Radishes- Chervil / Cucumber / Lettuce (protects radish from flea beetle) / Nasturtiums / Peas

Silverbeet – Beetroot / Lavender / Onions

Spinach – Strawberries

Strawberries – Borage / Lettuce / Sage / Spinach

Sweetcorn – Broad beans / Cucumber / Melons / Potatoes / Pumpkin / Squashes / Tomatoes

  • Sweetcorn takes a lot of nitrogen from the ground, so follow up with peas and/or beans (which add atmospheric nitrogen to the soil) once sweetcorn has finished or even inter-plant to increase sweetcorn productivity.

Tomatoes – Asparagus / Basil / Cabbage (brassicas) / Celery / Chives / Cucumber / Marigolds (deter nematodes) / Nettles (protect against mould) / Nasturtiums / Parsley

  • Bury iron nails to protect tomatoes against cut worm.

Turnips – Peas

Zucchini – Nasturtiums (provide protection against aphids)

Bad companions

Some plants don’t work well together and may even be detrimental to the growth of each other.
Broccoli (left) and strawberries (right) do not go well together.

Bad Companions list

Apples – Grass / Potatoes

Beans – Fennel / Garlic / Onions (inhibit growth) / Sunflowers

Broccoli – Strawberries

Cabbages (brassicas) – Rue / Strawberries / Tomatoes

Carrots – Dill / Tomatoes

Cauliflower – Strawberries

Coriander – Fennel (coriander has poor growth in its presence)

Fennel – generally does not mix with other plants and is better grown on its own. It does grow well with dill but when they both flower, they will cross-pollinate.

Garlic – Beans / Peas

Hyssop – Radishes

Kohlrabi – Tomatoes (kohlrabi reduces the growth of tomato) / Beans

Lettuce - Fennel

Mint – Parsley

Onions – Beans / Peas / Turnips / Parsnips / Asparagus / other alliums with the exception of leeks (they can be planted with other alliums as they deter onion flies)

Parsnip – Cabbages / Carrots / Celery /

Peas – Garlic / Onions (inhibit growth)/ Potatoes / Shallots

Potatoes – Apples / Cherries / Cucumber / Pumpkin / Raspberries / Rosemary / Sunflowers / Tomatoes

Pumpkins – Potatoes

Radishes – Hyssop / Potatoes

Raspberries – Blackberries / Potatoes

Rue – Basil (poisons the rue) / Cabbages / Sage

Spinach – Cabbages (brassicas)

Strawberries – Brussels sprouts / Cabbages / Cauliflower / Tomatoes

Sunflowers – Potatoes (sunflower growth becomes stunted)

Tomatoes – Apricots / Fennel / Kohlrabi / Potatoes / Rosemary

Companion planting – Herbs

Herbs make excellent companion plants as they often produce strong fragrances and other chemicals that can improve the health and quality of plants growing nearby.
Many herbs make good companions
Chives

Herbs Companion list

Basil – Tomatoes / Asparagus / Parsley / Apricots / Apples / Grapes 

  • Basil works well with parsley and summer savory as well as beans, onions and potatoes.

Borage – Strawberries (borage encourages the growth of strawberries so the fruit is healthy and tasty, and the leaves are more resistant to fungi and other diseases) / Broad beans / Courgettes / Cucumbers / Grapes / Marrow/squash / Tomatoes

Calendula – Artichokes / Beans (all varieties) / Peas / Potatoes

Chamomile (Roman or German) – Mint (chamomile enhances the flavour of mint) / Cabbage family / Onions / Peas / Tomatoes

  • Chamomile is generally good for other plants as it improves their health and promotes the production of essential oils in the companion.

Chervil – Dill / Coriander

Chives – Parsley / Apples (growing chives near apple trees will help keep the trees free of apple scab) / Carrots / Cabbage / Grapes / Leeks / Roses / Tomatoes

Coriander – Dill / Chervil / Anise / Carrots / Cabbage / Radishes / Spinach

Dill – Coriander / / Cabbage / Brussels sprouts / Cauliflower / Celery / Kohlrabi/ Leeks

Fennel – Cabbage / Leeks / Marrow/squash

Garlic – Apples / Runner beans / Lettuce / Peaches / Plums / Roses

Geraniums – Grapes

Horseradish – Fruit trees / Potatoes

Hyssop – Grapes / Cabbage family

Lavender – Cabbage / Citrus / Tomatoes

Lemon balm – Potatoes / Tomatoes

Marjoram –Beans / Broccoli / Cabbage / Potatoes

  • Marjoram generally improves the growth and flavour of plants growing nearby.

Marigolds – Lettuce / Potatoes / Tomatoes / Roses / Beans

Mint – Cabbage family / Peas / Tomatoes

Nasturtiums – Apples / Apricots / Courgettes (Zucchini) / Cabbages / Cauliflower / Broccoli/ Brussels sprouts / Kohlrabi / Turnips / Radishes / Cucumbers / Zucchini

Oregano – Cabbages

Parsley – Tomatoes / Asparagus / Chives / Roses / Artichokes / Lettuce / Potatoes / Mint

Rosemary –Sage (stimulate growth in each other) / Cabbage family / Beans / Carrots / Tomatoes

Sage – Rosemary / Carrots / Cabbage family / Grapes / Tomatoes

Savoury summer – Beans / Onions / Potatoes

Sunflowers – Squash / Cucumber

Tansy – Cabbages / Roses / Raspberries / Grapes

  • Tansy is a strong insect repellent.

Thyme – Cabbage / Eggplant / Beans / Lettuce / Cauliflower

Yarrow – Raspberries / Sweetcorn 

Plant root depth

Another consideration when planting different types of plants together is how their root system grows. Plants which have roots close to the surface should be planted next to those which have deeper roots. Planting vegetables with different root-growth habits together will utilise nutrients from varying soil depths and thus reduce competition between the plants.

Plants with shallow roots (30-45 cm)
Broccoli / Brussels sprouts / Cabbage / Cauliflower / Celery / Chinese cabbage / Corn / Endive / Garlic / Kohlrabi / Bok choi / Lettuce / Onions (Leeks, Chives) / Potatoes / Radish / Spinach / Strawberries

Plants with moderate-depth roots (45-60 cm)
Beans / Beets / Cantaloupe (Rockmelon) / Carrots / Chard / Cucumber / Eggplant / Kale / Peas / Peppers / Squash (summer) / Turnips

Plants with deep roots (60-75 cm or more)
Artichokes / Asparagus / Okra / Parsnips / Pumpkins / Rhubarb / Sweet potatoes / Tomatoes / Watermelon / Squash (winter)

Broccoli (left) and spinach (right) have similar root depths and, ideally, should not be planted directly adjacent to one another.