Companion planting folklore has existed for centuries. Although modern research often validates the effectiveness of some companionships, we don’t understand all the reasons why it works. Effective organic gardening techniques often implement many types of companion planting.
This article covers the benefits of companion planting, and provides practical suggestions for how to implement companion planting principles in your home garden.
Some of the benefits of successful companion planting include:
- Fewer pests
- Increased beneficial insects and pollinators
- Wider diversity and beauty in garden plantings
- Increased health and productivity of plants
5 Tips for Successful Companion Planting
1. Understand what not to plant next to each other
Many plants have different light and water requirements and should not be planted next to each other. There are also some plants that can thwart one another’s growth or cause them to be more attractive to pests and disease. Luckily, there are just a few to be aware of, such as:
- Do not plant beans and peas near onions, leeks, or garlic; they inhibit the growth of one another.
- Keep corn away from tomatoes; they share a common pest (corn ear-worms).
- Do not plant potatoes near tomatoes; it may spread blight.
- Fennell can inhibit the growth of many vegetables; it’s best to plant it near but not in the garden.
2. Implement polyculture practices in your garden
Polyculture: A variety of plants to each bed or plot of land.
Monoculture: A single type of plant in each bed or plot of land.
Adding a wide variety of herbs, flowers, vegetables, and fruit to your garden will benefit it more than any one specific companion plant combination. Diversity in plantings attracts a broader assortment of beneficial insects and pollinators. Provide food and shelter within your garden for those pollinators and beneficial insects.
I began my gardening journey using square foot gardening methods. This is the method I continue to practice today. One reason why this method is successful is the natural polyculture that results from interplanting several different types of fruits, vegetables, herbs, and flowers within the same bed.
A monoculture (think long rows of the same crop) makes it much easier for pests to find their intended crop.
How to implement polyculture practices:
- Learn how different crops grow so that you can plant different crops with similar light and water requirements near each other.
- Don’t be afraid to plant a variety of different vegetables, herbs, and flowers in each bed.
- When a spot (or square) opens up in your garden, fill it.
- Add perennial herbs to your garden beds.
- Resist the urge to plant all of one type of vegetable in one location. Add it to different areas around your garden.
- Try planting different varieties of the same crop (squash, beans, tomatoes, etc.) in various parts of the garden.
- Learn which flowers grow well from seed, and plant a square or two of each bed with flower seeds.
- Interplant crops with different timing. For example, as cool season crops come to an end add warm season crops. Once the cool season crops are harvested the warm season crops will be ready for the extra room.
3. Practice companion planting to attract beneficial insects and pollinators
As you implement polyculture practices (see Tip #2) and provide diverse habitats and food, your garden becomes more attractive to beneficial insects and pollinators.
Do not kill off the beneficial insects by using pesticides. One reason pesticides are harmful is they often have unintended consequences and do not discriminate between the good bugs and the pests.
How to encourage more beneficial insects and pollinators in your garden:
- Eliminate all use of pesticides.
- Use organic pest control methods sparingly and with a light hand.
- Provide diverse habitats and food sources for beneficial insects.
- Leave flowering herbs and flowers in place past blooming, and delay clean-up.
- Practice no-till methods in your garden.
- Plant as many beneficial insect-friendly plants as possible (see list below).
- Include flowering annuals, herbs, and perennials in your garden.
- Leave stems of plants in place for nesting bees and other insects.
Beneficial insect and pollinator-friendly plants:
Alfalfa, alyssum, angelica, basil, borage, buckwheat, butterfly weed, caraway, chervil, clover, coreopsis, coriander (cilantro), cosmos, dandelion, dill, fennel, gloriosa daisy, lavender, lemon balm, lobelia, lovage, mallow, marigold, mint, parsley, prairie sunflower, Queen Anne’s lace, rudbeckia, scabiosa, statice, sunflowers, tansy, thyme, tithonia, zinnia.
4. Use companion plants as supports or shade for one another
Although this first happened in my garden by accident (cucumbers found a nearby sunflower), I’ve since learned to use it to my advantage. With a little planning, you can use plants’ physical characteristics to benefit one another as tall stalks provide support for vining crops.
Utilizing the vertical space of tall plants allows you to grow more in less space. Vertical gardening also has other benefits such as increased sunlight and airflow, increased pollination, ease of harvesting, and spotting pests.
5. Practice companion planting to repel pests
Fewer pests is often considered the main goal of companion planting. There are a couple different methods for repelling plants using companion planting methods.
Use a companion plant to mask or block the desired crop from pests
It’s not completely understood how the pests are repelled or attracted to certain plants, but some companionships have proven to be effective.
Pest that may be repelled
Onion root maggot fly, Cabbage root fly
Use a "trap crop" to divert pests
Using a trap crop is planting something that is more attractive to pests than your desired crop.
- Plants used as trap crops should be planted earlier than the main crops.
- Typically, plant trap crops around the perimeter or near the plant you are protecting.
- Once the pests are on the trap crop, the pests should be removed/eliminated to keep them from reproducing.
- Trap crops work best for pests that are a regular nuisance.
Possible Trap Crops
Blue Hubbard squash
Squash vine borer
Blue Hubbard squash, nasturtium
Blue Hubbard squash, nasturtium, amaranth
Root maggot, cabbage maggot
Carrot root fly
Colorado potato beetle