Cucumber companion plants: what to plant with cucumbers?

Companion planting or growing certain plants with other crops for their mutual benefit has long been practised by home gardeners. Discover which plants are beneficial to grow cucumbers with and which are not.

Although there is little research to support the organic practice of companion planting, gardeners have grown companion plants together for years and often swear by it. Creating polycultures in your garden rather than monocultures creates little ecosystems that encourage pollinating insects and even help prevent disease. As with most homegrown crops, some plants grow well with cucumbers (Cucumis sativus) and others do not.

Good cucumber companion plants

There are numerous cucumber companion plants to choose from, including herbs, ornamentals and vegetables. Companion plants for cucumbers can benefit cucumbers by deterring pests, adding valuable nutrients to the soil and even providing supports for them to climb up.

Here are a few plants that grow well with cucumbers:

• Borage (Borago officinalis)
• Dill (Anethum graveolens)
• Chives (Allium schoenoprasum)
• Dwarf beans (Phaseolus vulgaris)
• Peas (Pisum sativum)
• Sweetcorn (Zea mays)
• Sunflowers (Helianthus annuus)
• Nasturtiums (Tropaeolum)
• Marigolds (Tagetes)
• Onions (Allium cepa)
• Lettuce (Lactuca sativa)

Some herbs are excellent cucumber companion plants. Dill and borage are great for growing with cucumbers as they attract predatory insects such as parasitic wasps, which can help control aphid populations while also encouraging pollinators to aid cucumber pollination. Cucumber and borage are both commonly used as garnishes for the Pimm’s summer drink, so growing them next to each other could be ideal.

The ornamental nasturtium has long been used as a sacrificial plant for blackfly and other aphids, as it attracts the pests away from your prized cucumber plants. Plant the nasturtiums a little away from your cucumbers to avoid any negative consequences. Marigolds, on the other hand, are known to produce a scent that actually deters some aphids and, due to their compact size, are perfect for growing under cucumber plants.

Cucumbers require a lot of nitrogen when they are actively growing, which is often provided by granular or liquid feeds as well as the soil. Read our expert article to find out more about how to fertilise cucumbers for the best harvest. Nitrogen can also be added naturally as a by-product of growing legumes like peas and dwarf beans, which fix nitrogen back into the soil via their root systems.

Cucumbers are often grown vertically to ensure good air circulation around the plant and to save space. Canes and trellises are often used for cucumbers to climb up, but plants can also be used for this. Cucumber and corn, as well as cucumber and sunflowers, are great plant combinations to grow. Their thick strong stems can provide supports for some smaller cucumber fruiting varieties to climb up, though they may buckle under a heavily laden large variety.

The allium family, known for its distinctive smell, can also be used for companion planting with cucumbers as their scent repels pests. Onions can be grown nearby, and low-growing chives are great for planting beneath cucumbers. Plus, both chives and onions make great additions to summery cucumber salads.

Lettuce and cucumber are also a good pairing as lettuce are light feeders and will not compete for any nutrients. What is more, growing the two together makes harvesting for light summer dishes even easier.

Bad companion plants for cucumbers

There are not many plants that should not be planted with cucumbers, but some will strongly compete for nutrients and moisture, attract more pests and even alter the flavour of the cucumbers.

Here are a few plants that do not grow well with cucumbers:

• Pumpkin (Cucurbita)
• Squash (Cucurbita)
• Courgette (Cucurbita pepo)
• Potato (Solanum tuberosum)
• Broccoli (Brassica oleracea var. italica)
• Cabbage (Brassica oleracea var. capitata)
• Kale (Brassica oleracea)
• Sage (Salvia officinalis)
• Mint (Mentha)
• Tomato (Solanum lycopersicum)

Cucumbers and other gourds, squashes, pumpkins, and courgettes are all members of the Cucurbitaceae family. For this reason, it is best not to plant them together as they all attract the same pests and diseases, which, if they strike, could harm more than just your cucumbers.

Another pairing to avoid growing together is cucumbers and potatoes because both are heavy feeders and will compete for precious nutrients and moisture in the soil. Another reason not to plant them together is that they can both be infected by blight fungus, with cucumber blight potentially increasing the likelihood of potato blight if grown close together.

The brassica family (Brassicaceae), which include broccoli, cabbages, and kale, are also not recommended as companion plants for cucumbers as they require lots of moisture to produce their leafy growth, taking the soil moisture away from the cucumbers.

Some herbs are not considered beneficial companion plants for cucumbers due to their strong scent, which is said to affect the flavour of the cucumber fruit. Sage and mint, which are known for their powerful aromas, are especially not recommended on this basis.

Growing cucumbers and tomatoes together, is one companion pairing that deserves a little more explanation. Cucumbers and tomatoes both prefer a warm environment and have similar growing requirements, so growing them together makes sense as well as being easier to care for. However, because they are both heavy feeders, require a lot of moisture and light, and need adequate space around them to promote healthy air circulation, they may compete. In light of this, if you want to grow cucumbers and tomatoes together, it is best to plant them 45 – 60 cm apart and in separate soil if possible.

Crop rotation

Crop rotation is not only a good way to organise and plan your garden, but it can also help promote soil health by maintaining nutrient levels, as well as prevent pests and diseases. A three-year crop rotation, on the most basic level, divides crops into the groups of potatoes, brassicas and legumes, onions and root vegetables and specifies that these groups are grown in rotation rather than in the same place year after year.

When it comes to cucumber crop rotation, it is recommended to not plant them or any other members of the cucurbit family in the same site more than once every three years, as this can encourage soil-borne diseases and deplete the soil’s nutrients. Where this is not possible, such as in a greenhouse bed or containers, dig the soil out when pulling the cucumber plants out and replace with new compost, such as our Plantura Organic Tomato & Vegetable Compost the following year.

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If you want to maximise growing space, and depending on your local climate, sow a quick early crop of lettuce or dwarf green beans before planting your cucumbers and if growing in a greenhouse, plant a hardy winter salad mix after the cucumber season.

Along with companion planting, cucumber plants only reach their full potential and provide the bountiful harvests we desire when grown at the right time and in the right place. Check out our article on how best to plant cucumbers to learn all about it.