Onion Companion Crops: Allium Allies

Accompanying planting is an old but popular strategy. Gardeners and farmers have been using this organic gardening technique for years, and it is seeing some kind of revival in the backyard garden. As people try to forego artificial fertilizers and pesticides to refine more natural practices, growing companion crops has become more important. For those who stock their home pantry, choosing the right onion companion plants is essential to get maximum yields.

Your goals with companion planting should be carefully considered. An accompanying planting like beans and strawberries works well because the beans provide the strawberries with nitrogen and the strawberries cover the soil, keeping it moist for the beans. Likewise, the benefits of planting onion companions only come into play if done correctly.

While planting onions and other allies like garlic from seeds can be quite difficult, growing from "onion sets" is a lot easier. This term refers to a baby onion that grows and develops into a full size onion. This fast growing plant is almost a safe choice and comes in handy when you accompany it with other plants. Also, remember to plant onions that have already sprouted.

There are all sorts of reasons for a companion plant. Some plant pairings result in better tasting foods. Others lead to fewer pests. Some companion plants provide each other with shade or structure such as corn and beans, while others can shade the soil and store water, such as the large leaves of the pumpkin plant.

As you plant onions in your garden, you will realize what problems you may have that the onions could help with. Did you want sweeter harvests? Less bad harvests? Did you want to get a bigger harvest out of your row of carrots or lettuce? See where onions can really help improve your garden and plan accordingly!

What is accompanying planting?

Choosing the right onion companion plants is the key to your success. Source: Julie

Underplanting is a system of growing different plants either one below the other (think of a carrot between each bulbous plant) or in adjacent rows or beds. With accompanying planting, each plant can in some way help another by growing nearby. This help can come in the form of improved taste, pest control, nutrient distribution, structure, weed control, shading, or water retention.

How does the accompanying planting work? There are different possibilities. Take peas and beets as an example. The roots of the pea plant develop nodules that fix nitrogen in the soil around its roots. This nitrogen is then fed to the beets, helping them grow bigger and healthier. This type of accompanying planting is known as nutrient sharing.

One of the best-known examples of good companion plants are the "Three Sisters" grown by the Native Americans. These are corn, beans, and pumpkin. The corn stalks grow tall and provide support for the bean vines to grow. The beans add nitrogen and fertilize the soil, while the pumpkin leaves protect the soil and retain water and prevent weeds. This symbiotic relationship results in a much healthier harvest.

Some plants, like yarrow, attract beneficial insects. Not only butterflies and bees like this colorful plant, lace flies are also attracted by the cloud-like structures of the yarrow flowers. Lacewings eat aphids – one of the most common pests in the garden, which not only eats and harms plants, but also spreads diseases. This type of accompanying planting reduces pests.

Radishes are great around onions, especially onion sets that are not yet sticking out of the ground. Radishes germinate quickly and mark where the row of onions that are not yet visible grow. This allows you to mark your garden rows with a companion plant.

As you will see with growing onions, the fragrance of many members of the onion family can repel garden pests such as Japanese beetles, the carrot fly, and cabbage worms. By planting certain plants with others, you can avoid crop damage before they start.

One way to catch pests that are always present in the garden (like aphids) is to plant nasturtiums. The nasturtium is used as a sacrificial or trap fruit. It attracts the aphids, and once it is infected it is plucked from the garden and disposed of. It doesn't hurt that the nasturtium flowers are lovely too!

Good onion companion plants

Spring onion flowersSpring onions, like other onions, produce spherical inflorescences. Source: starmist1

Onions are a great companion plant for members of the cabbage family (commonly known as the cabbage family), and not just because you can find them in the same dishes! The pungent smell of the onion helps repel pests that naturally prey on cabbage, broccoli, kale, or cauliflower, namely cabbage worm, cabbage claws, and cabbage maggots. Members of the cabbage family like kale, broccoli, Brussels sprouts, and napa cabbage do well when planted near these hot onions in the garden.

For gardeners fighting aphids, the entire onion family makes good companion plants around tomatoes, lettuce, strawberries, and peppers such as peppers or jalapenos. You will find that growing onions near tomato plants can add even more flavor to the tomatoes. In the case of lettuce or strawberries, the scent of the onions planted next to them also drives away some other juice-sucking pests.

Onions can also scare off spider mites, which means that planting tomatoes, peppers, and onions together is a great boon to these delicious plants. Spider mites can do serious damage to these plants and stunt foliage growth, so having companions around to slow them down is a good choice. Putting together a mix of onions, peppers, tomatoes, and marigolds will seriously reduce pest problems in your peppers and tomatoes!

Onions can be a root crop, but onions draw a different nutrient content in the soil than carrots or parsnips. When mixed with carrots, spinach, and lettuce, they actually don't compete for nutrients. They grow together well because they feed on different levels of the soil. The carrot sends its taproot deep into the ground for feeding, while the onion tuber pulls soil from the top few inches. The lettuce and spinach are even flatter than the onions. This method allows you to achieve a gradual series of root growth in the soil.

While intense, this type of gardening will bring in a great harvest of vegetables! The smell of the onion will also ward off the carrot fly, a common carrot pest. The aroma also repels many other species of pests such as aphids and flea beetles. This symbiotic relationship between lettuce, carrots, and onions makes them one of the most popular pairings of plants.

Use root crops like radishes to pop up quickly to mark rows where your slow growing bulbs are. The radishes will be ready by about the time the bulbs are visible and you won't accidentally overplant.

Many herbs planted next to onions can even improve the taste of the onions. Herbs such as summer or winter savory, marjoram, rosemary and dill improve the taste of onions. Mint and parsley also improve the flavor of your onions, while summer savory makes them sweeter! Just be careful and consider adding onions to your herb bed rather than the other way around. Mint can take over your garden box, and fast-blooming dill and parsley plants can drop seeds that return annually.

Another range of companion plants that will grow together in the garden are chamomile and onions. Chamomile's antifungal nature helps prevent some onion fungal problems, a problem in more humid climates. The chamomile plants also attract beneficial insects to the garden that can eat bugs such as aphids.

One option for the orchard ravaged by Japanese beetles or aphids would be to put containers in the orchard and plant onions, carrots, and summer flowers, or herbs like marigolds, dill, summer savory, and parsley. Not only do you get extra veggies, but the companions work together to improve the health of your garden. The bulbs reduce pests, while the flowers attract beneficial insects that can pollinate your orchard buds.

What not to plant with onions

Onions and herbsOnions are great partners for most herbs. Source: dayeraph

There are a few plants that you should avoid planting with your bulbous plants. Different plants interact with each other differently and are not all good companions.

A summer vegetable that you should never grow near onions is asparagus. Since asparagus is a perennial plant and takes years to establish, it is best to place the two plants in completely separate areas of the vegetable garden. Planting onions together with asparagus creates competition for soil nutrients.

Other vegetables that don't do well with onions include beans, peas, and most of the other plants in the legume family. The presence of the plants in the allium family can damage beans and peas as they can stunt their growth. There is a chemical incompatibility that prevents peas, field beans, runner beans, green beans, lentils, or other legumes from forming a stable and beneficial relationship. Avoid garlic, onions, leeks, and other allium plants in the same bed as these plants.

As with most plant families, members of the allium family are often plagued by the same diseases and pests. For this reason, it is beneficial to keep other members of the allium family (think leeks, garlic, chives, shallots, garlic-chives, and other onions) away from each other. If you plant these vegetables together, they will likely attract many of the same pests, namely onion maggots and onion flies. Both pests can do serious harm to your plants and stunt the growth of your future bulbs.

Another garden vegetable companion to stay away from is sage. While sage is known to stimulate the growth of a wide variety of vegetables, onions are not one of them. Keep your onion crop away from sage as it can actually stunt the growth of your plants!

In addition, planting beets with onions together leads to a loss of taste, only this time with the beets.

frequently asked Questions

Red onionsRegardless of the color or variety of the onion, they are all useful. Source: Blue Yonder

Q: Can I plant onions with cucumbers?

A: Not only will the onion odor repel pests that eat cucumbers, but the roots of the onion plants grow in a different layer of soil than the deep taproot of the cucumber.

Q: can onions be planted with tomatoes?

A: Yes, they are one of the best plants to grow next to your tomatoes. The smell of the onion plant and other allium plants can repel insects and bugs that prey on tomatoes if you plant onions near tomatoes.

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