can you plant onions and tomatoes together

Can You Plant Onions and Tomatoes Together? A Guide to Companion Planting These Popular Veggies

Many gardeners wonder if it’s a good idea to plant onions and tomatoes together. After all these are two of the most popular vegetables that home growers cultivate. Companion planting involves planting different crops in close proximity so they can benefit each other. But is this an effective technique for onions and tomatoes? Let’s take a closer look at the science and practical considerations behind planting these veggies together.

The Benefits of Companion Planting Onions and Tomatoes

Companion planting has numerous advantages when done correctly. Here are some of the main benefits of planting onions and tomatoes together:

• Pest control – Onions help repel pests like aphids, spider mites, rabbits, and deer that can damage tomato plants The strong scent of onions masks the smell of tomatoes and confuses pests

• Enhanced flavor – Onions can subtly enhance the flavor of tomatoes. Likewise, tomatoes bring out the sweetness in onions.

• Improved growth – Onions provide nutrients to tomatoes. The shallow onion roots also aerate and break up the soil, allowing better airflow and growth for tomato roots.

• Space efficiency – By planting compatible crops together, you maximize productivity in each square foot of your garden.

• Natural weed control – Dense plantings help suppress weeds by blocking sunlight access. The extensive root systems also absorb water and nutrients before weeds can get to them.

• Disease prevention – Onions and tomatoes can help prevent each other’s diseases. Onions deter fungus, while tomatoes deter rot.

As you can see, onions and tomatoes form a symbiotic relationship. The onion protects the tomato and improves the soil and flavor. Meanwhile, the tomato shades the onion bulbs and repels onion maggots.

Factors to Consider When Companion Planting Onions and Tomatoes

While onions and tomatoes complement each other nicely overall, you need to plant them properly to get the full benefits. Here are some important factors to consider:

Light requirements – Tomatoes need at least 6-8 hours of full sunlight per day. Onions can tolerate partial shade, especially in hot climates. Make sure the onions don’t shade out the tomatoes.

Soil needs – Onions prefer slightly alkaline soil with a pH of 6.0-7.0. Tomatoes thrive in slightly acidic soil with a pH of 6.0-6.8. Test and amend your soil to fall within compatible pH ranges before planting.

Watering needs – Tomatoes require consistent moisture when setting and ripening fruit. Onions prefer drier soil and can rot in wet conditions. Use drip irrigation and pay attention to each plant’s needs.

Spacing – Allow at least 12-18 inches between onions and tomatoes to prevent crowding. Plant tomatoes in the center with onions around the border to maximize light and space.

Timing – Plant onions 2-4 weeks before tomatoes so they can establish themselves first. Onions grow best in cool weather and tomatoes in warm weather.

With a little extra care, onions and tomatoes can flourish side-by-side. Just be observant of their individual requirements.

How to Companion Plant Onions and Tomatoes

Follow these tips when companion planting onions and tomatoes:

• Before planting, test and amend your soil pH to the optimal range for each crop (6.0-7.0 for onions and 6.0-6.8 for tomatoes).

• Work aged manure or compost into the soil to provide nutrients. Onions and tomatoes are heavy feeders.

• Choose disease-resistant varieties of both onions and tomatoes. This prevents transmitting blights between the two.

• Start onion sets or transplants 2-4 weeks before transplanting tomatoes. The onions establish first and won’t compete with mature tomatoes later on.

• Plant onions on the north side of tomatoes so they don’t block sunlight to the tomatoes as they grow.

• Allow 12-18 inches between the onion sets and tomato plants. Close enough for companionship yet far enough apart to prevent crowding.

• Use drip irrigation or soaker hoses to water the soil directly. This prevents foliar diseases. Water when the top few inches become dry.

• Place organic mulch like straw or leaves around the plants to retain moisture and discourage weeds.

• If necessary, use cages, stakes, or trellises to support the tomato vines as they grow tall.

Follow these companion planting guidelines, and your onions and tomatoes will thrive! Monitor their growth and make adjustments to spacing, supports, and watering as needed.

Troubleshooting Onion and Tomato Companion Planting Issues

Even when following best practices, you may encounter some problems when growing onions and tomatoes together:

• Shading – If onions grow too large, they can block sunlight from reaching the tomatoes. Use trellises and cages to keep tomato vines above the onion leaves.

• Competition – The two crops may compete for water and nutrients if planted too closely together. Allow adequate space and enrich the soil to provide enough resources.

• Disease transmission – Onions and tomatoes can spread diseases like blight to each other if the plants already have issues. Start with disease-free transplants.

• Attracting pests – Onions may attract onion maggots. Tomatoes can draw in hornworms. Hand pick pests and use organic remedies like neem oil.

• Allelopathy – Onions release a chemical that inhibits tomato growth. Use raised beds and space plants far enough apart to allow good airflow.

With attentive garden management, any issues that arise can be promptly addressed. Both onions and tomatoes are highly rewarding crops for home gardens.

Companion Planting Onions and Tomatoes with Other Vegetables

In addition to pairing with each other, onions and tomatoes combine well with these other common vegetables:

Onions:

• Carrots – Mask each other’s scents to confuse pests. Onions deter carrot fly insects. Carrots shade onion bulbs.

• Beets – Beets deter onion maggots. Onions deter leaf miners, aphids, and beet diseases.

• Lettuce – Onions repel slugs, aphids, and rabbits that can damage lettuce. Lettuce provides shade for onions.

• Cabbage – Onions deter cabbage moths. Cabbage repels onion flies and maggots.

Tomatoes:

• Asparagus – Asparagus repels harmful nematodes around tomato roots. Tomatoes deter asparagus beetles.

• Spinach – Spinach provides shade and moisture retention. Tomatoes deter leaf miners on spinach.

• Celery – Celery helps tomatoes to grow stronger. Tomatoes protect celery from cabbage loopers.

• Carrots – Carrots lure tomato hornworms away. Tomatoes provide shade for carrots.

Get creative with companion planting in your garden. You’ll discover all sorts of effective plant pairings.

Growing Tips for Onions and Tomatoes

Here are some additional growing tips to help your onions and tomatoes thrive:

Onions:

• Plant onion sets or transplants 1-2 inches deep in fertile soil in early spring. Place them 2-4 inches apart in all directions.

• Side dress with nitrogen-rich fertilizer when the onions start bulb formation. This fuels the rapid bulb growth.

• Water onions 1-2 inches per week. Less watering causes bigger, tastier bulbs to form.

• When the tops turn brown and flop over, bend the stalks to expedite ripening. After 2 weeks, lift the bulbs and allow them to further cure in a warm, dry spot.

Tomatoes:

• Start seeds indoors 6-8 weeks before your last expected frost date. Harden off plants and transplant outdoors after danger of frost.

• Space tomato plants 24-36 inches apart in rows or raised beds. Plant in nutrient-rich, well-draining soil.

• Use tomato cages or stakes to support the heavy vines and keep fruits off the ground.

• Water tomato plants consistently, about 1-2 inches per week. Too much or too little water can cause problems.

• Side dress with nitrogen fertilizer when the first flower clusters appear. Discontinue by late summer so plants can focus energy on fruit ripening.

Follow these growing guidelines for a bountiful onion and tomato harvest!

The Bottom Line on Companion Planting Onions and Tomatoes

Onions and tomatoes are crop companions that bring out the best in each other. Onions deter pests, improve soil nutrients, and enhance tomato flavor. Meanwhile, tomatoes provide shade for onions while repelling onion maggots.

With proper planting techniques, spacing, soil preparation, and attentive care, onions and tomatoes can flourish together in the same garden beds. Take advantage of their symbiotic relationship by incorporating companion planting into your vegetable gardening strategy. You’ll be rewarded with a productive vegetable garden and delicious onion and tomato harvest.

Yes, peppers and onions are generally considered excellent companion plants. Onions have a strong scent that repels common pests that bother peppers, like aphids and spider mites.