Better Together: Companion Planting Beyond Folklore

by Lorraine Sharaf 

Practical plant partnerships to try in the August garden

By August, the vegetable garden is very different from the tidy, well-spaced collection of small plants we admired in spring and early summer.

Tomatoes are tilting into paths. Cucumber vines are visiting neighboring plants and winding around everything along the way. Basil and dill are beginning to flower, and empty spaces have opened up where peas, lettuce, radishes, or early beans were harvested.

Don’t fret if your garden seems a little out of control or some harvests appear to be winding down. The garden isn’t nearly finished. It is simply ready for its next arrangement.

At the end of last month’s wrap-up of the 12 permaculture principles, reader Adam Dusen of Hundred Fruit Farm shared this quote from renowned permaculturist Larry Santoyo:

“You don’t DO permaculture. You use it in what you do.”

So this month, we are not going to “do permaculture.” Instead, we will use permaculture thinking and design tools to help our Bucks County gardens transition from summer into fall—beginning the fall garden while summer is still growing.

Although we’ll focus primarily on vegetable gardens, many of these same ideas can also be applied to perennial beds.

🌱 More Than a Companion-Planting Chart

Companion planting is often presented as a colorful chart of garden friends and foes:

Tomatoes love basil.
Carrots love onions.
Beans hate this.
Potatoes refuse to grow beside that.

Some of these combinations may be useful. Others come mostly from gardening tradition and have been repeated so often that they begin to sound proven.

A more thoughtful approach asks practical questions:

• Will one plant make better use of the space beneath or between another?
• Will a quick crop be harvested before a slower one needs the room?
• Will flowers provide nectar and pollen for beneficial insects?
• Will a low-growing plant shade the soil or suppress weeds?
• Could mixing plant shapes, scents, and colors make a crop harder for a pest to locate?
• Do the plants need similar amounts of water, sunlight, and soil fertility?

The goal is not to determine which vegetables are best friends. It is to identify what each plant can contribute.

Several related terms help describe what we are doing.

A polyculture is a planting that contains several species rather than a single crop growing alone.

Interplanting places different crops in the same space at the same time.

Succession planting passes a space from one crop to another as the season progresses.

Companion planting deliberately combines plants because we expect the partnership to provide a particular benefit.

These practices often overlap. A gardener might plant radishes between young kale plants, allow dill to flower nearby, and later replace the harvested radishes with spinach. That one bed becomes a polyculture, an interplanting plan, a succession plan, and a beneficial-insect planting all at once.

🌳 Borrowing a Pattern From the Forest

A forest—or a well-designed food forest—is not arranged in tidy rows of one species. Trees, shrubs, ground covers, fungi, insects, and other organisms share the space in layers and create countless relationships. Our vegetable beds are much smaller and more managed, but we can adopt the same pattern of mixing heights, harvest times, and functions so the garden behaves more like a community than a line of individual plants.

Here are three ways to try this in an August garden.

🥬 Plan 1: The Fast-and-Slow Fall Bed

This plan combines a large, slow-growing fall vegetable with a quick crop that can be harvested before the larger plants need the space.

Plant together:

• Kale, collards, or broccoli transplants
• Radish seeds
• One dill, cilantro, or calendula plant near the edge

Place the kale, collards, or broccoli according to their mature spacing. Don’t crowd them simply because the plants look small now. They will eventually need room to spread.

Sow radishes in short rows or small clusters in the open spaces between them.

Radishes germinate and mature quickly. By the time the brassicas begin filling the bed, many of the radishes will be ready to harvest. Their departure makes room for the slower crop.

Place a flowering herb or calendula near the northern edge of the bed, where it is less likely to shade the vegetables. If dill or cilantro is already growing elsewhere in the garden, there may be no need to transplant another. Simply allow one plant to flower.

What is each plant doing?

• The radishes provide a quick harvest while the larger plants are still small.
• The brassicas become the bed’s primary fall crop.
• The flowering plant provides nectar and pollen for beneficial insects, including some small wasps and flies whose offspring feed on aphids or caterpillars. Flowering herbs such as dill, cilantro, and basil are particularly useful for attracting pollinators and the natural enemies of garden pests.

This is not a magical combination in which radishes protect kale from every pest. It works because the plants use different amounts of space at different times, while the flowers contribute another function.

Make it your own

No kale transplants? Try collards, Swiss chard, or another cool-season plant suited to the space.

No radishes? Baby lettuce or another quick-growing leafy green could fill the temporary openings.

The important design question is:

What can I harvest before the main crop needs the space?

🥗 Plan 2: The Summer-to-Fall Handoff

Gardeners often wait until tomatoes, peppers, and eggplants are completely finished before beginning fall planting. By then, valuable growing time has been lost.

Instead, let the outgoing summer crop shelter the incoming fall crop for a short period.

Look for:

• The north or east side of a tomato, pepper, or eggplant plant
• An opening that receives light but is protected from the fiercest afternoon sun
• Enough space to avoid restricting airflow around the established plant

Plant:

• Leaf lettuce
• Arugula
• Mustard greens
• Parsley
• Later in the season, spinach

Sow a small patch of greens or tuck in several transplants near, but not directly against, the established summer plant.

The taller plant may provide filtered shade during the hottest portion of the day, helping young cool-weather crops through their vulnerable first weeks. As temperatures cool and the summer crop slows down, remove it carefully. The younger plants can then expand into the newly opened space.

For a short time, the summer and fall crops are interplanted.

As the older crop is removed and the younger crop takes over, the same arrangement becomes succession planting.

Together, the plants form a temporary polyculture.

It’s like a relay race: one season passes the baton to the next instead of the gardener ripping out one garden before beginning another. University of Maryland Extension similarly recommends using the shade cast by taller crops for young greens and beginning new plantings before the previous crop has completely finished.

A word of caution

Don’t force fall crops beneath dense, diseased, or sprawling tomato plants simply because there is technically soil underneath them. Young greens need light, water, airflow, and access, so look for a genuine opening rather than a crowded corner.

New seeds will also need consistent moisture. During August heat, check them daily at first. A light mulch spread after germination can help protect the soil, and temporary shade cloth may be useful during an especially hot spell.

The design question for this plan is:

Can an established summer plant help the next crop get started without overwhelming it?

🐞 Plan 3: Open a Tiny Beneficial-Insect Café

By late summer, gardeners are often pinching flower buds from basil and pulling herbs that have begun to bolt. But allowing a few herbs to bloom can provide food for some of the insects that help the garden.

Choose one or more:

• Dill
• Cilantro
• Basil
• Oregano
• Thyme
• Calendula
• Anise hyssop
• Mountain mint or another well-behaved native mint relative

Allow a few plants to flower near vegetables rather than harvesting every stem.

The small, accessible flowers of dill and cilantro are especially valuable to many small beneficial insects. Adult syrphid flies, also called hover flies, feed on nectar and pollen, while their larvae eat aphids. Some tiny parasitic wasps also need flowers as adults, even though their developing young feed on garden pests.

Basil, oregano, thyme, calendula, and anise hyssop can also extend the garden’s supply of flowers. Providing flowers throughout the season supports beneficial insects that consume or parasitize garden pests.

Try a five-minute observation

Quietly stand or sit near the flowers for five minutes.

Look for:

• Bees gathering pollen
• Flies hovering like tiny hummingbirds
• Small wasps moving between flowers
• Beetles, butterflies, or moths feeding
• Spiders waiting nearby

The visitors may not all be familiar, and not every insect must be immediately identified. The first step is simply to notice how much activity one flowering plant can support.

Allowing one basil plant to flower might mean a little less pesto or Caprese salad, but it creates a much better restaurant for the garden’s smallest workers.

The design question is:

Could I harvest most of this plant while leaving part of it to serve the overall garden?

🧪 Beyond Folklore: What Companion Planting Can Do

The three plans above don’t depend upon plants “liking” one another. They are based on observable functions.

A plant partnership may:

• Use vertical space more efficiently
• Provide several harvests from the same bed
• Shade and protect the soil
• Keep living roots in the ground
• Supply flowers over a longer period
• Attract pollinators and beneficial insects
• Interrupt the large, uniform blocks that make some crops easier for pests to find
• Increase the overall diversity of the garden

Some aromatic plants may interfere with the visual or chemical signals insects use to locate a host plant. In other cases, a low-growing companion may make it more difficult for an insect to reach the soil or lay eggs near the crop.

But these effects are usually specific. A plant that helps reduce one pest under particular conditions should not automatically be promoted as a universal insect repellent. Companion planting charts may contain long lists of claims that are not supported by research or that apply only under particular conditions.

Companion planting is one tool among many. Healthy soil, appropriate spacing, crop rotation, row covers, careful observation, hand-picking, and tolerance for a small amount of insect damage still matter.

🎯 Sometimes a Companion Takes One for the Team

Some companion plants help by attracting pests rather than repelling them. These trap crops, or decoy plants, lure pests away from the crops we hope to harvest.

Borage is a superstar in the garden, producing bright blue, star-shaped flowers that attract bees and other beneficial insects. In my garden, it also draws some of the damaging insects that might otherwise attack my peppers and eggplants. I can then monitor the borage closely and remove heavily infested portions before the pests move onto my harvest crops.

Borage has been studied as a plant that can harbor aphids while also attracting parasitoid wasps that attack them. However, a successful trap plant must be watched so that pests do not eventually disperse back to the crop being protected.

The same idea may work with birds. Red mulberries ripen around the same time as blueberries, and birds often flock to their abundant, easy-to-reach fruit. A fruiting mulberry nearby may draw some attention away from blueberries, cherries, or raspberries. It will not distract every determined visitor, but offering birds a fruit they love may lessen the competition. Netting, of course, is still the surest way to protect the harvest. Red mulberry fruit matures from June through August and is a favorite food of many birds and other wildlife.

🌼 What About Marigolds?

Marigolds may be the most famous companion plants of all.

They can add diversity, supply flowers for insects, and, in some circumstances, help suppress particular plant-parasitic nematodes. Research has identified benefits involving specific marigold varieties, crops, and pests.

What marigolds do not create is an invisible force field around the vegetable garden.

Their effectiveness against nematodes depends upon the marigold variety, the nematode species, the planting method, and other conditions. Simply placing a few marigolds beside a susceptible crop does not guarantee protection.

Plant them for flowers, habitat, and beauty, and for any specific, researched purpose that applies to your garden. Just don’t expect a few marigolds at the end of a tomato row to run security for the entire garden.

⚖️ Better Together Does Not Mean Packed Together

A productive polyculture is not a competition to fit the greatest possible number of plants into a bed.

Before adding a new crop, ask:

• How large will each plant become?
• Will one be harvested before another needs the space?
• Do the plants have compatible light, soil, and water needs?
• Can air still move through the planting?
• Can I reach everything to water, inspect, and harvest it?
• Will one plant shade another helpfully or excessively?

Open space can be an opportunity, but not every visible inch must be filled. The purpose is to create useful relationships—not a crowded bed that is difficult to manage.

🌳 From Polycultures to Permaculture Guilds

Each of our three August plans is a small polyculture: several plants sharing space and contributing different functions.

A permaculture guild takes this idea a step further. It is an intentionally designed polyculture, often organized around an anchor plant such as a fruit tree or large shrub. Other plants are selected to meet the needs of the entire site and one another.

One might cover the soil. Another might attract pollinators. Others may produce food, contribute mulch, support wildlife, recycle nutrients, or occupy different layers above and below the ground.

A guild asks the same question we have been asking throughout this article:

What work needs to be done here, and which plants could help do it?

Next month, we will choose an anchor plant and build a small permaculture guild step by step.

For now, begin with one open space.

Could it hold a quick harvest while another plant grows? Could a summer crop shelter a fall seedling? Could one herb be left to flower for insects? Could a finished section begin feeding and protecting the soil?

You do not have to “do permaculture.”

Just use it in what you do.

🌾 Permie Tip: Create a Patchwork Cover

Not every opening needs to produce another vegetable.

Where you want an additional harvest, plant a fall crop. Where you are finished growing food for the year, consider sowing a cover crop.

Cover crops can:

• Keep living roots in the soil
• Protect the ground from erosion
• Capture nutrients that might otherwise be lost
• Suppress weeds
• Feed soil organisms
• Add organic matter

There is no need to clear the entire garden before beginning. Add cover crops section by section as summer vegetables finish, gradually turning the bed into a patchwork of food crops, flowers, and soil-building plants.

Oats are often manageable for beginners because they grow quickly and, when planted promptly in August, generally die during the winter in our climate, leaving plant material that can protect the soil. Other cover crops survive winter and require a spring management plan, so choose according to when you are planting, what you want the crop to accomplish, and what you intend to grow in the bed next year. Penn State recommends planting spring oats in southeastern Pennsylvania by approximately September 1 for the greatest benefit, although conditions can affect the planting window.

Even here, the permaculture question remains the same:

If this space is no longer feeding us, how might it feed and protect the garden?

Resources and Further Reading

• Hemenway, Toby. Gaia’s Garden: A Guide to Home-Scale Permaculture. 2nd ed. White River Junction, VT: Chelsea Green Publishing, 2009.
• Penn State Extension. “Herbs Make Good Plant Partners and Companions.”
• Penn State Extension. “Attracting Beneficial Insects.”
• Penn State Extension. “Philadelphia Planting Guide.”
• Penn State Extension. “Tips for Planting Cover Crops in Home Gardens.”
• University of Maryland Extension. “Vegetable Succession and Companion Planting.”
• University of Minnesota Extension. “Companion Planting in Home Gardens.”
• Sarkar, Subhendu C., et al. “Application of Trap Cropping as Companion Plants for the Management of Agricultural Pests: A Review.” Insects 9, no. 4 (2018): 128.
• U.S. Forest Service. “Red Mulberry.” Silvics of North America.