How Close Is Too Close For Companion Planting? (Sample Layouts)

interplanted garden bed of greens, kale, cilantro

When I started my first garden, I planted everything in isolated rows because that’s what I was taught. It wasn’t long before I began to tuck random plants here and there wherever there was room, unknowingly using companion planting to my advantage.

This method turned out to be a much better way to maximize space and diversify my planting area, and my garden thrived as a result. But, I had to learn a few things about the proper spacing for companion planting along the way.

The best way to space companion plants is to follow the recommended planting distance between the two plants. If one plant needs 4 inches of space and the other needs 8 inches, then the recommended spacing between them will be 6 inches.

Companion planting is the way to go if you also want to take advantage of every corner of your garden. Just keep a few spacing guidelines in mind to avoid any potential problems. With proper planning, your garden will be thriving in no time!

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Um… what’s companion planting?

Just in case this is the first growing season that you’re hearing about companion planting, here’s what it is in a nutshell:

Companion planting is a gardening technique that involves growing certain plant pairs together to benefit each other. Some plants can improve the growth and health of other plants while repelling pests or attracting beneficial insects, while others are complementary in growth habits and space needed.

Basically, you’re trying to foster a mutually beneficial relationship between two plants. It’s a great way to build a healthy and diverse garden.

How close does a companion plant need to be for maximum effectiveness?

For the companion plants to be mutually beneficial, they do not always need to be next to each other. There can be some distance between the two different plants, and you’ll still get the benefits, so don’t let an awkward garden space or having multiple small plots stop you from companion planting. 

On the other hand, don’t be afraid to pack in the plant pairing and situate them next to each other. There are some instances where it becomes incredibly beneficial to have your companion plants close together.

alyssum planted under kale plants
This is a great example of maximizing space and the effectiveness of beneficial pairings in the garden. Alyssum, kale, lettuce, and snapdragons all share the same space to produce food and attract pollinators.

For instance, if you’re planting pole beans with sunflowers or corn, it will be beneficial to grow them very close to the companion plant so the beans can climb the sunflower or corn stalks.

The way to space companion plants is to look at the standard planting instructions for the two plants involved and use their average as your planting distance.

For example, if one of the two plants has a recommended spacing of 12 inches and the other has a spacing of 6 inches, then take the average of the two and plant your companion plants 9 inches apart as an ideal spacing.

This method is particularly effective if you’re growing plants with different growing habits. For example, combinations of lettuce and radishes, or chives and carrots, can be planted close together because they have different root depths and plant heights.

Here’s a practical example:

Lettuce requires 6-9 inches between plants, and radish needs just 2-3 inches. You could alternate one lettuce and two radish seeds at 4-6 inches apart, and each vegetable would have enough room to grow. The radish will mature faster than the lettuce, so once you harvest the radish, the lettuce will have that last inch or two of space it needs to fully mature.

Interplanting radishes among lettuce plants means you get larger harvests in the same amount of space.

Staggering plantings for closer spacing

One of the leaders in companion planting and mixing crops in one garden bed is John Jeavons, author of the book “How To Grow More Vegetables.” He uses the same method that I’ve just explained, where you take the average of the recommended planting distances of your two different plants. However, he takes it one step further. He recommends planting in offset rows. 

Offset rows mean that the plants in the second row are in line with the midpoint between plants in the first row. Staggered planting allows you to plant rows closer together without overcrowding or wasting space.

Think of it like staggering cookies on the baking pan. By offsetting the cookie dough, each one has room to spread without running into the next cookie.

Companion plants pest control vs. pollinator-attractor distances

In addition to saving space, companion planting excels at helping with pest control and attracting pollinators and beneficial insects. Although any interplanting can help with either of these goals, if you’re looking for the best way to plan your garden, here is some specific information to consider.

Pest control and prevention

Pest control from companion planting works because the pests are looking for a specific type of plant to eat. If you have multiple types of plants growing next to each other, the pests can be confused and not know which plant to go after. At the very least, mixing different plants can slow down a bug’s progress through the garden bed.

A classic example is planting alliums (members of the onion family) with carrots to deter carrot flies. The onions, garlic, or shallots will mask the scent of the carrots, so the damaging carrot fly moves on without visiting the carrot crop.

Staggering planting, mentioned above, is a fantastic way to not only save space, but also to help fool pests who use scent to find their favorite crops. Carrots and onions are a classic combination in the garden.

Another common practice is to use companion trap crop, such as nasturtiums. These flowers are excellent at drawing pests like aphids away from more valuable crops like kale or cucumbers.

For this type of companion planting, it’s beneficial to plant the different crops close together. The average distance guideline I mentioned above would be best to get the most impact.

Attracting pollinators

When using companion planting to attract pollinators and beneficial insects, you don’t always have to combine both plants in the same garden bed.  

Instead, what can be beneficial is to plant a floral border around your primary crop or garden area. Besides looking pretty, these flowers create a pollination zone that encircles your whole garden area, catching the attention of insects as they fly by.

In this case, the spacing is pretty straightforward: follow the spacing guidelines for the type of flowers you’re growing. This can range from six to 18 inches, depending on what kind of flower you’re growing.

Some of the best flowers for companion planting are native and wildflowers that are common to your area. These tend to attract the greatest range of beneficial insects to your garden. These seeds can be scattered and left to grow at the random spacing they fall in, or you can see what sprouts and thin them to leave about a foot between plants.

If you prefer to buy your flower seedlings, some of the most common ones at the garden center that make excellent pollinator plants are

  • zinnias
  • cosmos
  • marigolds
  • alyssum
  • sunflowers

Plant your seedlings about a foot apart, and they’ll thrive. You can use tighter spacing if you know you’re going to harvest some of the flowers for bouquets. Harvesting from the plant frequently keeps it well-pruned and needing less space.

Spacing for companion planting in rows

If you prefer to garden in rows rather than mix your crops together, you can still use companion planting methods with close spacing. Sometimes rows are better when you’re planting large amounts of one crop, such as tomatoes for canning. 

For the spacing, stick to standard spacing recommendations for each plant type. For example, plant your bed of tomatoes with two feet of space between your tomato plants and your second companion plant at its intended spacing in its row.

For example, you’d have one row with tomatoes at 2-foot spacing. Then the next row could be marigolds (a classic combo!) spaced 9-12 inches apart.

Row spacing for companion planting follows the traditional plant spacing since the plants are offset. This method is fantastic for planting beneficial plants close to each other, such as marigolds and tomatoes.

When you grow this way, your companion plant can still be effective up to three rows away, so you could even have multiple rows of one crop before mixing in a row of flowers or companion vegetables. Keep in mind that the effectiveness of the companion plant gradually reduces with greater distance, so don’t space things out too far.

If you don’t want to sacrifice garden space for a row of flowers, try planting a border around the primary crop. Planting a large border of flowers is a powerful signal to insects passing by, who look for large swaths of the same color and shape to land on.

Spacing for companion planting in containers

If container gardening is more your style, you can still use companion planting. The spacing is a little different when working with limited space in a container, but the basic idea is the same.

You’ll still want to follow the standard plant spacing in containers, but you should also pay attention to the growing habit of the plants you include. For example, if you’re companion planting basil and tomatoes in a pot, put the tomato in the center of the container with a cage or trellis. Then plant the basil around the edge of the pot at 6-12 inches apart.

Can companion plants be too close together?

Any combination of plants can be spaced too close together. If this happens, the plants will compete for resources like water and nutrients, and they may even start to overtake each other as they grow. The more robust plant will shade the smaller one, resulting in poor growth.

Besides small, fast-growing crops like radishes, most plants need at least 4-6 inches between them to allow for the healthiest growth. That said, it’s worth playing around with spacing to see what you can get.

If you live in a warm, sunny climate, you can probably space your plants together without adverse effects. If you live in a humid climate, you should leave more room between plants to maximize airflow and reduce the risk of fungal disease creeping in.

How far away should poor companion plants be?

As impressive as companion planting is, it’s a fact that some plants make very poor companions with other plants. One plant can stunt the growth of its companion through chemicals released into the soil, both crops are susceptible to the same diseases, or the growth habits of the two plants are simply incompatible.

For example, beets are said to perform poorly when planted with pole beans (though I haven’t tested it myself). Fennel is known to inhibit the growth of anything planted next to it because of its allelopathic properties, which release chemical compounds that can prevent germination.

This fascinating study discusses how plants can “talk” to each other through releasing chemicals that either welcome or reject their neighbors. In the example, the scientists note that a parasitic weed sniffed out its host plant and proceeded to grow toward it.

When in doubt, it’s always best to err on the side of caution and give poor companion plants a bit more space than you would for good companions. A few extra inches between these plants will go a long way in ensuring that they

Distance for poor soil companions

The minimum distance between plants that are poor companions should be at least double the regular recommended distance. The extra room gives each plant’s roots the necessary space without affecting the other plant.

If you have the space, it’s better to separate the crops by more than just the minimum to have better chances of each plant thriving.

I learned this in my own garden when I planted two competing plant families together, legumes with alliums (beans and onions, specifically). Legumes fix nitrogen from the air but rely on bacteria found in the soil. However, alliums exude chemicals through their roots that actively destroy the bacteria that the legumes need.

I found that the only way I could plant legumes and alliums near each other was by putting them in pots or having one in a raised bed and the other in pots so they wouldn’t share the same soil.

Distance for slowing down pests

Some plants attract the same pests, and combining them can potentially impact both crops, especially if you have problems with harmful insects. If you plant all your brassica crops close together (kale, cabbage, broccoli), then any pest that finds one can easily move on to the next and speed up their reproduction and damage.

beet and onion interplanted
These onions will help deter pests that would otherwise chew on the beet leaves. Notice that little caterpillar in the foreground?

A better strategy would be to increase the space between the different crops and mix in a different vegetable or flower to interrupt the pest’s movement. For example, you could plant a row or block of kale, then a block of marigolds, then a row of lettuce. You can keep close spacing to save room, and the variety of plant families will make it harder for pests to move from one crop to another.

Distance for incompatible growth habits

Finally, if you’re growing two or more companions with different growth habits, planting them too close can prevent one or both from thriving.

For example, if you’re companion planting flowers, both need space to access sunlight and water. Most flowers will do well planted about a foot apart, so if you grow them closer, you’ll need to monitor them to ensure they’re not crowding each other out.

A creeping alyssum can quickly be overshadowed by a bushy cosmos plant if planted too close. Two vining plants, such as sweet peas and hyacinth bean, will compete for the same trellis space, so they would need separate garden areas or double the normal distance between them to provide each of them to thrive.

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