Good and Bad Onion Companion Plants

It is important to know which plants can be grown alongside onions and which ones should be avoided when companion planting.

This article will discuss some of the best and worst companion plants for onions to maximize your onion harvest.

Good Companion Plants for Onions

Here is a list of the best plants to grow with onions in the vegetable garden.

• Broccoli
• Kale
• Tomatoes
• Brussels sprouts
• Peppers
• Chamomile
• Summer savory
• Pak choi
• Carrots
• Beets
• Eggplant
• Cucumbers
• Lettuce
• Amaranth
• Thyme
• Cabbage
• Cauliflower
• Strawberries
• Swiss chard
• Marigolds
• Celery
• Dill
• Mint

Moreover, green onions (scallions) also thrive next to many of these plants.

What Not to Plant with Onions

Below are some of the worst plants to grow with onions. These may inhibit their growth and development and harbor pests, among other things.

• Peas
• Beans
• Sage
• Asparagus
• Alfalfa
• Clover
• Wheat
• Squash
• Garlic
• Shallots
• Leeks

Wheat, clover, and alfalfa are bad companions because they may harbor onion thrips [1]. Squash, beans, garlic, shallots, peas, and leeks may also encourage harmful insects.

How to Grow Onions

You can grow onions from seeds, sets, or scraps. Onion sets are ideal for planting, as these small bulbs are more prone to bolting (flowering) earlier than smaller bulbs.

If using sets, plant them at a depth of 1 to 2 inches and a spacing of 2 to 6 inches. Additionally, separate rows 12 to 18 inches apart.

To grow from seed, start the seeds about 8 to 10 weeks before transplanting them outside. As a general guideline, place seedling transplants 4 to 5 inches apart in 12 to 18-inch-wide rows.

Furthermore, onions thrive best in nutrient-rich soil and full sun. To provide space for bulb growth, thin out plants that are becoming too thick in the planter.

You may use the young plants from the thinning as spring onions in the kitchen.

Care and Maintenance

Plants will begin developing bulbs in the summer when the temperature warms up.

Onions are ready for harvesting when the leaves turn brown and droop over. However, allow the onions to dry out in the garden for a few days before storing them.

Keep them in a cool, dry place until you’re ready to use them when the outer skin is dry and papery.

Light

Long-day onions need at least 14 hours of direct sunlight daily to thrive. On the other hand, short-day onions require at least 10 hours of sun per day [2].

Soil

To grow these plants properly, you need the right soil. It must be fertile, well-drained, loose, light, and loamy.

Additionally, add some organic matter. The ideal soil pH range for onions is 6.0 to 7.0.

Water

The plants require adequate water to sustain their growth. Water them once a week to avoid bulb rot. However, don’t overwater them or leave them in waterlogged soil.

Fertilizer

Onions are heavy feeders. Therefore, to develop large bulbs, treat the plants with a high-nitrogen fertilizer such as Nitrogreen every few weeks.

This will support leaf growth. However, stop feeding the onion bulbs when they begin to push the earth away.

Pests and Diseases

Below are a few of the pests and diseases affecting onion plants.

Rot

Neck rot, bulb rot, and leaf rot are common. To prevent rot, ensure that the soil is well-drained and aerated.

Thrips

Onion thrips may cause damage to leaves and give them a white or silvery appearance. Soapy water and neem oil are excellent natural treatments for thrips.

Onion Root Maggots

Onion flies lay their eggs at the base of the plant. The maggots from these eggs then crawl deep into the plant stems, feeding on the roots and destroying the onion plants below the soil.

Rotate your plants every year to keep them free of pests. Diatomaceous earth also works.

Harvesting 

The time it takes for onions to develop varies. However, they may be harvested at any stage. Even seedlings pulled from a row can be utilized as green onions.

When about half of the top leaves have fallen off and the bulb skins have a papery texture, the bulbs are completely grown. You may achieve longer-lasting storage by allowing bulbs to stay in the ground until at least half of their green tips have fallen.

Allow the bulbs to dry out in the ground for a few days before removing them.

Digging up the onion bulbs rather than plucking them out is a preferable strategy. Only a little digging is necessary to remove the residual roots.

Allow the bulbs to dry out in a warm, dry environment with sufficient air circulation while they finish curing. Don’t remove the leaves. You may use your fresh onions whenever you choose.

Where to Buy Seeds

Quality seeds are essential when you’re ready to start your plants from seed. Several local farm stores sell vegetable seeds of all kinds.

You can also buy high-quality organic seeds from trusted online stores.

Takeaway

Onions are fairly easy to cultivate. However, it is important to know which vegetables, herbs, fruits, or flowers grow well with them.

Companion planting is a common practice for promoting garden well-being. By placing certain crops next to each other, you can naturally repel various pests, attract helpful insects, and boost plant growth.

Use the list above to determine exactly what to plant near onions and what not to plant next to them.