Companion planting is a gardening technique that involves growing different crops together to improve growth, boost yields, and reduce pests. Onions, with their strong scent and pest-repelling properties, are a great plant for companion planting. In this guide, we’ll explore the benefits of companion planting with onions and which plants pair best with them to help you create a thriving garden.
What Is Companion Planting?
Companion planting is based on the idea that some plants benefit each other when grown together. These benefits can include:
- Pest control: Some plants repel pests that may damage neighbouring plants.
- Improved growth: Certain plant pairings can enhance each other's growth by improving nutrient uptake or providing shade.
- Soil health: Different plants can help maintain soil health by fixing nitrogen, breaking up compact soil, or attracting beneficial insects.
Onions are a versatile companion plant that can support a range of vegetables, herbs, and flowers, making them a valuable addition to any garden.
Benefits of Companion Planting with Onions
Onions provide several benefits to their companion plants:
- Pest repellent: Onions produce a strong odour that can deter many common garden pests, such as aphids, carrot flies, and cabbage worms.
- Space efficiency: Onions take up little space and can be planted between other crops, making them an ideal companion for space-saving garden designs.
- Weed suppression: Their shallow roots can help prevent weed growth, reducing competition for nutrients.
Best Companion Plants for Onions
Onions are compatible with many different plants. Here are some of the best companions to plant alongside your onions:
1. Carrots
Onions and carrots are a classic companion planting pair. Onions help repel carrot flies, while carrots may deter onion flies. Planting these two crops together can significantly reduce the presence of pests that could harm either crop.
2. Lettuce
Lettuce and onions make great neighbours in the garden. Onions can help repel pests like aphids that might otherwise target tender lettuce leaves. Additionally, lettuce grows quickly and can be harvested before onions mature, making efficient use of garden space.
3. Beetroot
Onions pair well with beetroot, as they don’t compete for the same nutrients. Beetroot grows deep roots, while onions have shallower roots, meaning they occupy different soil levels, allowing them to grow well together without inhibiting each other’s growth.
4. Tomatoes
Onions help to repel common tomato pests, such as aphids and spider mites. Tomatoes, in return, don’t interfere with onion growth, making this pairing beneficial for both plants. Keep in mind that onions are shallow-rooted, so they won’t compete with the deeper-rooted tomato plants.
5. Strawberries
Onions can help deter pests that target strawberries, such as slugs and aphids. Additionally, onions and strawberries don’t compete for nutrients or space, making them good planting companions.
6. Chamomile
Chamomile is a fantastic herb to grow near onions. It helps enhance the flavour of onions and attracts beneficial insects like bees and ladybirds, which can help control pests in your garden.
Plants to Avoid Planting Near Onions
Not all plants are suitable companions for onions. Some plants can compete with onions for nutrients or are susceptible to diseases or pests that onions might attract. Here are a few plants you should avoid planting near onions:
1. Legumes (Peas and Beans)
Peas and beans fix nitrogen into the soil, which onions do not benefit from. In fact, onions can stunt the growth of legumes by competing for nutrients, so it's best to keep these plants in separate parts of your garden.
2. Sage
Sage is a perennial herb that doesn’t pair well with onions. Sage prefers different growing conditions and can hinder onion growth, so it’s best to plant these two in different areas.
3. Asparagus
Asparagus is a deep-rooted perennial that requires lots of nutrients, which can lead to competition with onions. Asparagus beds should be kept separate from onions to avoid stunted growth.
Tips for Companion Planting with Onions
To get the most out of companion planting with onions, follow these tips:
1. Plant in Rows or Clusters
Plant onions in rows or small clusters among your other crops. This will help maximise the pest-repelling benefits while ensuring the onions have enough space to grow properly.
2. Rotate Crops Annually
Onions can deplete soil nutrients over time, so it’s important to rotate them each year. Avoid planting onions in the same spot year after year, and try to alternate them with nutrient-fixing plants like legumes (but not in the same growing season).
3. Mulch and Water Well
Onions like well-draining soil but still need consistent moisture. Applying mulch around the base of your onion plants will help retain moisture and suppress weeds. Water onions regularly, especially during dry periods, to encourage healthy growth.
Final Thoughts
Companion planting with onions is a great way to improve your garden’s health and productivity. By pairing onions with the right plants, you can enhance growth, protect crops from pests, and make the most of your garden space. Whether you're growing vegetables, herbs, or flowers, onions are a versatile and beneficial companion plant for many different crops.
At Marshalls Garden, we offer a wide selection of onion varieties and companion plants to help you create a thriving garden. Visit us today to explore our range of seeds, plants, and gardening supplies for a successful growing season.