7 Onion Companion Plants and Why You Need Them

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Onions are a great addition to any garden. Not only are they delicious in numerous recipes from salsa to soup, but, they are also an important ingredient in apothecary preparations like fire cider. While growing in the garden, it can be beneficial to have onion companion plants both for onions and utilizing onions.

Why Grow Onions Anyways?

According to WebMD, onions contain a plethora of health benefits when eaten. Some of these include: decreased risk of cancer, diabetes, Alzheimer’s, heart attack and stroke.

They are a rich source of sulfur as well as many other vitamins and minerals beneficial to the human body!

In addition to this, onions also contain antioxidants, specifically quercetin, which help reduce inflammation.

What better way to add these nutrient storehouses to your home than to grow them yourself?

Onions take up relatively little space within the garden, and can be planted both in the early spring as well as late summer for both a summer and a fall/early winter harvest.

This allows for an increased harvest, especially if you have a small garden and are trying to conserve square footage while maximizing yield!

So what are companion plants?

Companion plants equate to the close planting of a variety of crops, flowers, or herbs that benefit each other in some fashion.

In her book, Plant Partners, Jessica Walliser describes this as:

Using plant partnerships to improve the overall ecosystem of the garden and create a well-balanced environment in which all organisms thrive, from the tiniest soil microbe to the tallest corn plant.

It’s about thinking through, observing and then utilizing a combination of plants to help each other in some way, shape or form throughout the growing season.

What Plants are Good Companions for Onions?

What are some of these good companion plants for onions?

There are a number of herbs, which, when planted near onions, are thought to help improve their flavor and growth. These include:

• chamomile
• summer savory
• dill
• parsley
• mint

It is important to note that with some herbs, such as mint, you want to be diligent to make sure they don’t take over your garden.

Some people prefer to plant mint, and other invasive herbs, in pots throughout the garden rather than in the ground where they will happily spread.

Outside of improved growth and flavor, there are several other plants that can be beneficial to plant with onions for other reasons.

You could plant some form of nutrient accumulator (amaranth, etc.) near onions to improve production and soil nutrient density.

Finally, planting some variety of chop and drop (mulch) plant near onions can be beneficial to them as well!

In What Ways are Onions Good Companion Plants?

Because of their strong scent, onions are wonderful at repelling insects from other plants.

In light of this, planting things such as:

• brassicas
• potatoes
• tomatoes
• peppers
• strawberries
• etc.

near your onions can markedly decrease a pest population due to the smell of the onions masking the scent of your other crops.

Similarly, onions or other alliums can be used in fruit tree guilds for the same purpose.

The Big 7

1. Herbs

Planting herbs alongside onions has a beneficial effect on each. The onions can mask certain scents, thereby confusing pests that could damage the herbs.

While the herbs can assist the onions in their growth as well as sweetening and mellowing out their flavor profile. Some of these herbs, while mentioned above are:

• chamomile
• summer savory
• dill
• parsley
• mint

2. Brassicas

The brassica family encompasses many different plants, a majority of which quite enjoy being planted close to onions for their pest control effect. This family includes:

• broccoli
• cauliflower
• kale
• cabbage
• collards
• etc.

3. Potatoes

Similarly, onions are great to plant with potatoes due to their strong scent and ability to ward off pests. As an extra bonus, they don’t interfere with the growth of potatoes because they are so shallowly located in the soil!

4. Tomatoes

Onions are good to plant with tomatoes as a pest deterrent. That said, there is some evidence that would suggest if you have issues with thrips not to plant onions near tomatoes, as they are also susceptible to damage from this insect.

5. Peppers

When planting onions with peppers, they work as a pest deterrent for slugs and cabbage worms among others. They also fit quite nicely interplanted with your peppers since they take up only a small amount of space!

6. Flowers

Flowers, both edible and ornamental can benefit from being planted near onions. There is evidence that marigolds and roses specifically are good companions with onions.

Some people think that planting marigolds near onions will help reduce harmful nematode infestation in the soil.

7. Carrots

Carrots are another crop that benefit from onion companion planting. The onions act as a pest deterrent. Some say that this works specifically for the carrot root fly.

In addition, the carrots can also help protect your onions from the onion fly.

A win, win for everybody!

Things to avoid planting onions by:

Four common plants that should not be planted near onions are:

• legumes
• peas
• sage
• asparagus

It is thought that if onions are planted near any of these, it will cause them to be stunted and may affect their flavor in a negative way.

In light of this, it is probably a good idea to avoid planting these crops near onions just to be on the safe side.

No one wants off tasting peas or asparagus!

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