A Full Guide to Companion Plants for Your Garden

Did you know that companion planting can maximize your gardening space, increase plant growth, and ward off pests? By choosing plants, flowers, and herbs that complement each other, you can grow a garden that produces more vegetables and improves the health of your plants and soil. Picking companion plants that don't compete with each other is essential—and it'll make your gardening a lot easier.

We went straight to the experts to provide you with the best companion planting guide for your garden. 

What is Companion Planting and How Does It Work?

"Companion planting is growing different plants close to each other so they can benefit from each other," says Jane Dobbs, an expert gardener and gardening team lead at Allan's Gardeners. "Some plants can enhance the growth, flavor, and resilience of other plants, as well as control pests and diseases. The natural relationships between plants can help improve productivity and health in the garden."

She continues, "For instance, you can deter nematodes and aphids with marigolds. Certain plants can help their neighbors grow by supplying nutrients, improving soil health, or supporting them physically. Nitrogen-loving plants like spinach and lettuce benefit from legumes like beans and peas fixing nitrogen in the soil."

You can also maximize your garden space with companion planting. "Plants with different growth habits, like deep-rooted varieties and shallow-rooted varieties, can grow together without competing," she informs. 

3 Simple Rules for Companion Planting

"There are a lot of mixed messages out there about companion planting," says Nathan Heinrich, horticulturist and botanical designer. "What one expert says should be planted next to each other, another says you should never plant together. It's understandable that new gardeners can become confused and disheartened by all the noise."

He continues, "I'm going to give you three simple rules to determine which fruits and veggies you should plant next to each other. I prefer to call this good neighbor gardening rather than companion gardening. To understand which plants will make 'good neighbors' in your garden, there are three things to consider: height, leaf size, and root zone."

Consider the Plant's Height

The first rule is to consider the height of the plants you are pairing together.  "Some veggies like spinach and lettuce only get a few inches tall," Heinrich explains. "These shorter plants do very well when planted together, but they do not do well when planted with much taller plants that block their sunlight. Pole beans, peas, and corn are examples of some of the tallest plants in your garden, but they do not make good neighbors when planted in front of shorter varieties."   

He continues, "Now, the exception to this is if you position the tallest veggies at the back of your garden so that they do not cast a shadow over their shorter neighbors. Then, these tall and short plants can live in harmony. Just make sure you understand in which direction the sun comes into your garden and make sure your tall plants are not in the front, where they will block the light."

Factor in the Leaf Size and Shape

Heinrich says that just because two plants grow to the same height does not mean they will necessarily make good neighbors in your garden. Leaf shape makes as much of a difference as height. "Just imagine two people of the exact same height standing side by side on the beach.  One is wearing a baseball cap, and the other is holding a huge beach umbrella over their head.   Even though they are the same height, their shade impact is very different.  The same is true for vegetable plants, he explains.  

"Veggies with oversized leaves like rhubarb or squash have very large umbrella-like leaves that would shade out their neighbors with tiny leaves, like carrots or many herb varieties," Heinrich says.

Plant According to Root Zones

Heinrich says that another very important thing to consider when planning your garden is how compatible the root zones of your veggies will be. Potatoes are a wonderful crop that grows to approximately the same height with a similar leaf size as bush beans, but their root zones are completely different and totally incompatible.   

"When it comes time to harvest the potatoes, all the disruption and digging up of the soil to extract the potatoes will end up damaging the roots of the beans, potentially killing them," he warns.

He continues, "Root veggies such as carrots and beets actually do well together because they are approximately the same size, they take similar times to ripen, and are both harvested by pulling up the roots."

Benefits of Companion Planting

Melvin Cubian, a certified botanist and gardening expert for the PlantIn App, says that companion planting is a well-studied field in agriculture, with empirical-based evidence on its benefits. There are many benefits when it comes to companion planting, such as:

• Boosting crop yield 
• Improving soil quality
• Controlling weed growth
• Reducing water loss and erosion
• Improving plant health
• Attracting pollinators and other beneficial insects
• Maximizing garden space
• Reducing pests

So, whether you're a beginner gardener or have been gardening for years, the art of companion planting can improve your garden.

Companion Planting Chart 

Before heading to the gardening center, check out our companion planting chart to help you pick the best plant combinations for your garden. 

Crop	Companion Plants
Carrots	Beets, Spinach, Peppers
Lettuce	Strawberries, Dill, Onions
Yellow Squash	Rhubarb, Beans, Dill
Eggplant	Garlic, Spinach, Radishes
Onions	Leeks, Tomatoes, Eggplant
Tomatoes	Basil, Onions, Parsley
Sweet Corn	Pole Beans, Melons, Cucumbers
Chives	Oregano, Strawberries, Carrots
Pumpkins	Peas, Radishes, Beans
Garlic	Beets, Cabbage, Tomatoes
Arugula	Swiss Chard, Garlic, Onions
Radishes	Carrots, Common Beans, Cucumbers
Peas	Cucumbers, Celery, Turnips
Cabbage	Celery, Shallots, Garlic
Broccoli	Onions, Potatoes, Shallots

Companion Planting with Flowers

Dobbs says that many plants rely on pollinators like bees for fruiting. Planting flowers among crops will increase yields and pollination. "You can repel pests and attract pollinators with marigolds, nasturtiums, calendula, and sunflowers," she says. "Pick flowers with pest-repellent properties. Aphids, nematodes, and whiteflies hate marigolds."

"You can plant them around your vegetable beds to repel pests," she adds. "Clover and lupine are good at fixing nitrogen and adding organic matter to the soil."

Cubian recommends using plants such as alyssum and bitter melon to control weeds. He explains that alyssum is a creeping plant that carpets the soil, which prevents weeds from getting the sunlight they need to grow. So, flowers have many benefits and are an essential part of companion planting.

Companion Planting with Herbs

Dobbs explains that companion planting with herbs can boost the health and growth of your garden. "The herbs basil, dill, chives, and parsley promote plant growth and repel insects," she says. "Create beneficial plant guilds with herbs, vegetables, and flowers. If you plant rosemary with carrots, you'll deter carrot flies, and if you plant thyme with cabbages, you'll deter cabbage worms."

You need to pay attention to how herbs grow. "Herbs like mint are highly invasive, so plant them in containers to keep them from overwhelming your garden," she advises.  "Natural self-seeders like dill and cilantro can also spread naturally. Bees and butterflies love herbs because they produce flowers. Oregano, thyme, and lavender can help pollinate your garden, leading to more produce," she adds.

Avoid These Companion Planting Mistakes

Gardening takes patience and can be a process of trial and error. However, by following the simple companion planting rules and choosing plant combinations that complement each other, you can increase your chances of growing a flourishing garden.

Another way to ensure you have "green thumb success" is by avoiding these companion planting mistakes that Dobbs warns about:

• Avoid pairing the wrong plants: Plants don't always get along. When pairing plants, try to avoid those that compete for resources or have conflicting growth habits. Companion planting is more effective when compatible plants are combined. 
• Don't plant too close together: Planting too densely can result in competition for water, nutrients, and sunlight, stunted growth and reduced yields. Give your plants enough room to grow. Overcrowding and shading can happen if you plant fast-growing crops next to slow-growing ones. Consider each plant's growth rate and avoid overshadowing or stunting neighbors.
• Avoid planting at the wrong time: Planting companion crops at the wrong time can disrupt their natural growth cycles and reduce their effectiveness. Plant companion plants at the same time so that they mature at the same time.
• Don't neglect the soil: Plants have different soil needs. If you don't consider pH, fertility, and drainage, you may end up with nutrient deficiencies or soil-related issues. You can amend the soil to make it grow better.
• Avoid invasive plants. If introduced as companion plants, they can become out of control and outcompete native plants. Choose plants that aren't invasive.

"Monitor plant interactions and keep an eye out for competition, nutrient deficiencies, pest infestations, and other problems that can arise from companion planting," Dobbs advises.

With these companion planting guidelines, you can grow a flourishing garden season after season.