Companion planting is an age old tradition, especially companion vegetable planting. It’s a gardening technique that involves planting two or more plants near each other to derive some type of benefit. That benefit could be more vigorous growth, higher yield, repelling pests or attracting predators of common pests. Scientific research doesn’t always agree with the folklore of companion planting, but who knows?
Science changes and at the very least, we know that diversity in the garden cuts back on problems.
Learning which plants to pair as companions takes a bit of trial and error. For example: anise seems to germinate better when grown with coriander, but coriander doesn’t grow well next to anise. Garlic deters Japanese beetles, but planted to close to anything in the pea and bean family and it will inhibit their growth.
One of the most compelling reasons to use the companion planting technique is the ability of certain plants to attract beneficial insects. Beneficials are insects that feed on common garden pests, like aphids and caterpillars. Beneficial insects are considered the good guys and are why gardeners are cautioned not to spray insecticides at random.
Beneficial Insects That Should be Welcome In Your Garden
- Parasitoid wasps - feed on aphids, caterpillars and grubs
- Lacewing larvae - feed on aphids
- Ladybug larvae - feed on aphids
- Ground beetles - feed on ground-dwelling pests.
- Hover flies, and Robber flies - feed on many insects, including leafhoppers and caterpillars
Because insects tend to have different feeding requirements during the various stages of their development, a diversity of plant material is essential to attracting them.
Although beneficial insects do feast on pest insects, there may be certain points in their life cycles when their diets are confined to nectar and pollen. So to attract these insects to your garden, you will need to provide host plants and even plants for shelter.
Diversity in both plant material and season of availability are crucial. Hedge rows used to serve this function. The trees, shrubs and weeds would leaf out sooner in the spring than cultivated crops and provide early food sources.
Hedge rows are rare today, but we could easily plant a mixed border of fruiting and flowering trees and shrubs and perennials that has something in bloom all season. This patchwork of plants would benefit your ornamentals and planting it near a vegetable garden will insure beneficials on your vegetable crops.
What You’ll Need to Provide To Attract Beneficial Insects:
- Low growing plants as cover for ground beetles (thyme, rosemary, or mint)
- Shady, protected areas for laying eggs
- Tiny flowers for tiny wasps, like plants from the Umbelliferae family: fennel, angelica, coriander, dill, Queen Anne’s Lace, clovers, yarrow, and rue
- Composite flowers (daisy and chamomile) and mints (spearmint, peppermint, or catnip) to attract predatory wasps, hover flies, and robber flies
Herbs work especially well as companion plants. They multitask by attracting beneficial insects and repelling pest insects and their fragrance and foliage make them good companions in both the vegetable garden and the ornamental border. The following list is compiled from experience and other people’s suggestions. Keep in mind that some things work in conjunction with other factors in the environment and your results might not be the same as mine.
However with some tweaking here and there, you should be able to use plants to keep a better balance in your gardens.
Using Herbs As Companion Plants to Deter Pests
- Aphids - Chives, Coriander, Nasturtium
- Ants - Tansy
- Asparagus Beetle - Pot Marigold
- Bean Beetle - Marigold, Nasturtium, Rosemary
- Cabbage Moth - Hyssop, Mint (also clothes moths), Oregano, Rosemary, Sage, Southernwood, Tansy, Thyme
- Carrot Fly - Rosemary, Sage
- Flea Beetle - Catmint (Contains nepetalactone, an insect repellent. Steep in water and spray on plants.), Mint
- Flies - Basil, Rue
- Fruit Tree Moths - Southernwood
- Japanese Beetles - Garlic & Rue (When used near roses and raspberries), Tansy
- Potato Bugs - Horseradish
- Mosquitoes - Basil, Rosemary
- Moths - Santolina
- Nematodes - Marigold (Marigolds should be established for at least 1 year before their nematode deterring properties will take effect.)
- Savory, Winter - Some insect repelling qualities
- Squash Bugs & Beetles - Nasturtium, Tansy
- Ticks - Lavender (Also thought to repel mice and moths.)
- Tomato Horn Worm - Borage, Pot Marigold
Read more about gardening with nature in Organic Gardening Essentials.
Books for Further Reading:
Great Garden Companions (A Companion-Planting System for a Beautiful, Chemical-Free Vegetable Garden), by Sally Jean Cunningham, Rodale Organic Living Books
Carrot Love Tomatoes, by Louise Riotte, Workman Publishing Company