COMPANION PLANTING: what is it?
Many gardeners/farmers have known for a long time that plants grow better when they have certain other plants nearby. The opposite is also true. The idea that plants have ‘friends’ and ‘foes’ was dismissed by many experts as unscientific for some time but now that the theory has been studied and found to have a sound basis it has been given a name: allelopathy.
The ways in which one plant can help or hinder another is either through chemicals that are exuded through the roots or from the leaves. Pine trees and eucalypts for example release substances into the soil around them to inhibit the growth of other plants close by that would compete with them for nourishment. The aroma given off by some plants could also be a factor in the effect they have.
You will find a number of books on the subject in the gardening section of book stores and we suggest that you get one of them if you want to follow up on the subject. This booklet is intended only as an introduction to an interesting and helpful topic.
Several things must be kept in mind as you learn about companion planting. Some of the books on the subject were written in other countries and what is true of those environments might not be true of ours. As with most aspects of gardening you may hear claims made fervently but have no basis in fact. It can be confusing but keep an open mind and check out what you have heard with some knowledgeable person. In the end you will have to try things out for yourself.
This, by the way, is one of the advantages of belonging to HOGS: most of our members have already found out what works through trial and error and as a member you can avail yourself of that knowledge and expertise. After all, you don’t have to keep reinventing the wheel.
Companion planting means that the friends should be placed close to the plants being helped. They will not have much effect if planted a couple of metres away. On the other hand, a plant categorised as a foe may still have a place in your garden; just make sure they keep their distance. For example, the onion family do not get on with the legumes (peas, beans etc) so plant onions in a different bed to your peas; make sure they are not next door to each other.
The following information comes from gardening experience and can be acted on with confidence. The friends of each plant are listed first then the foes (if there are any). By ‘friend’ we mean plants that help the plant in question to thrive. By ‘foe’ we mean plants that will inhibit the growth and well-being of the plant in question.
| Crop | Friends | Foes |
|---|---|---|
| Asparagus | Tomato, parsley, basil | |
| Beans | Potato, carrot, cucumber, cauliflower, summer savory, most vegetables and herbs | Onion, garlic, gladioli |
| Beets | Onion, kohlrabi | Runner beans |
| Brassica (cabbage, cauliflower etc) | Aromatic plants, potato, sage, celery, dill, chamomile, beet, peppermint, rosemary, onion | Strawberry, tomato |
| Carrot | Peas, lettuce, chives, onion, leek, rosemary, sage, tomato, wormwood | Dill in flower, being stored with apples |
| Celery/celeriac | Leeks, tomato, bush beans, cauliflower, cabbage | |
| Chives | Carrot | Peas, beans |
| Corn | Potato, beans, peas, squash, cucumber, pumpkin | |
| Cucumber | Beans, corn, peas, radish, sunflower | Potato, aromatic herbs |
| Leek | Onion, celery, carrot | |
| Lettuce | Carrot, radish | |
| Melon | Radish | |
| Onion, garlic | Beets, summer savory, tomato, lettuce, strawberry, chamomile | Peas, beans |
| Parsley | Tomato, asparagus | |
| Peas | Carrot, turnip, corn, beans, radish, cucumber, most vegetables and herbs | Onion, garlic, potato, gladioli |
| Potato (not sweet) | Beans, cabbage, marigold, horseradish (plant at corner of patch), eggplant | Pumpkin, squash, tomato, cucumber, sunflower, raspberry |
| Pumpkin | Corn | Potato |
| Radish | Peas, nasturtium, lettuce cucumber | |
| Raspberry | Most vegetables | Blackberry, potato, tomato |
| Spinach | Strawberry | |
| Squash | Nasturtium, corn | |
| Strawberry | Bush bean, spinach, borage, lettuce | Cabbage |
| Sunflower | Cucumber | Potato |
| Tomato | Chives, onion, parsley, carrot, asparagus, marigold | Kohlrahbi, fennel, potato, cabbage |
| Peas | Turnip |
FURTHER READING
Jackie French: Jackie French’s Guide to Companion Planting in Australia and New Zealand
Brenda Little: Companion Planting in Australia
Louise Riotte: Carrots Love Tomatoes: secrets of companion planting for successful gardening