Companion Plants for Radishes | Good and The Bad

Radishes are one of the easiest root vegetables to grow and can be sown, grown, harvested and eaten in as little as 21 days making them perfect for even the most impatient gardener. 

They are packed with vitamin C and can offer colour, a crunch and a peppery kick to your summertime salads and sandwiches. 

Simple to grow and small in stature, radishes are a great candidate for companion planting taking up little space for only a short time and offering excellent ground cover for other taller plants. Plus they too will benefit from extra assistance with the right plant pairing.

Typically, there are good and bad companion plants which can make or break your crop come harvest time. But don’t worry because I’ve simplified the ancient growing technique of companion planting to help you choose the perfect pairing partners for those radishes.

Companion Planting Explained

Companion planting is a commonly used gardening technique where different plant species are grown close to one another to benefit one or both plants. There are lots of advantages to this growing method which is why companion planting has been used by gardeners for centuries, assisting the health of crops and improving the amount harvested.

From growers in China cultivating rice fields to the Native Americans growing sweetcorn, beans and squash plants, companion planting has been used to improve the condition of the soil, pollinate flowers, prevent pests and diseases, make the best use of space and offer support and shade for developing crops. 

Companion planting is a way of ensuring that plants remain pest-free in a completely organic way which means there is no need for pesticides. By choosing this method of growing, growers can encourage and support beneficial insects in their gardens to assist with plant pollination and manage pests naturally.

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There are a multitude of benefits to be gained from companion planting. Because this technique is completely organic it promotes a natural balance in the garden. Maintaining this balance can improve plant and insect diversity which will encourage and support beneficial predators and pollinators which ultimately improves plant health and harvest amounts.

Some other benefits of companion planting include:

Improved Soil Health: Plants need nutrient-rich soil to remain healthy and strong. A huge benefit of using crops such as legumes, peas or beans from the Fabaceae Family when companion planting is their ability to improve growing conditions. These plants absorb nitrogen from the air which is then converted and released into the soil where it then becomes available for neighbouring crops to utilize. 

Space Saving: Not all growers have a big garden to grow fruit and vegetables which is why companion planting is so appealing as it helps maximize growing space and makes use of areas of the garden which would’ve otherwise laid bare.

Interplanting smaller, quick-to-mature plants such as radishes, salad leaves or scallions amongst taller slow-growing plants like tomatoes or sweetcorn, saves space and increases harvest amounts.

Pest Control: Using strongly fragranced companions such as herbs, flowers or onions is an efficient method of protecting main crops from pest attacks. Aromatic herbs can help deter unwanted pests by masking the scent of the main crop confusing and diverting pests away. 

Additionally, plants such as sunflowers and marigolds can be used as ‘trap crops. These are planted sacrificially to draw pests towards them and away from the more desirable food crop.

Considerations When Selecting Companion Plants

Planning and preparation are key to having a happy and healthy growing environment and although there are many positive benefits, there must always be some consideration towards the potential negatives of companion planting. 

For example, there is a fine line between making use of growing space and overcrowding when planting. The temptation to squeeze in lots of different plant varieties can do more harm than good resulting in plants competing for space, water and nutrients resulting in a poor harvest all around. 

It’s best to keep plant choices simple by only choosing one or two planting partnerships in each garden bed, allowing these plants to establish and flourish before adding more.

Before choosing companions you will need to establish whether your plant choice is perennial or annual. Both perennial and annual plants can be used as companion plants, however, problems can occur if the two types are planted together thanks to the difference in lifecycles. 

Best Companion Plants for Radishes

Radishes are a popular choice for lots of gardeners thanks to how quickly they grow and how little space they need. When paired correctly, there are many benefits to be sought such as improving their flavour and size as well as protecting them against pests. 

Pests such as aphids and flee beetles are common problems for radish crops so using companions with a strong scent can help prevent attacks by confusing and diverting any unwanted visitors away from the plant.

Radishes may be fast growers, but they must be grown in the right conditions in order to achieve this. Plants will need to be grown somewhere with lots of natural sunlight. However, they are predominantly a cool weather crop and consistent temperatures over 80°F can cause them to bolt (go to seed). With this in mind, a good choice of plant companion can be those that grow taller which can offer shade to low-growing radishes in hotter climates.

All plants will benefit from nutrient-rich soil to assist with growth and improve yields and radishes are no exception. Ensuring they are healthy and paired with nitrogen-fixing plants will enable them to be better equipped to recover should they suffer from pests or diseases. 

Here are some other good examples of companion plants to grow with radishes:

Fruits and Vegetables

Parsnips: love them or loathe them, parsnips make great planting companions for radishes thanks to their pest-controlling abilities. It’s their strong scent that helps deter unwanted visitors. 

In addition to diverting pests, they also attract beneficial predators such as ladybugs which will further assist with pest control. 

Parsnips make great companions for radish
Parsnips make great companions for radish

Lettuce: Interplanting leafy greens alongside radishes is the perfect way to make full use of every inch of soil space. This allows for a more diverse mixture of plants to be grown. Both lettuce and radishes have similar needs and maintenance requirements. 

The added advantage is they take approximately the same length of time to reach maturity which means they can be harvested and enjoyed at the same time. 

Peas, beans and other legumes: Plants from the legumes family add nutrients to the soil by absorbing nitrogen from the air and fixing it in the ground which radishes can then use to boost their growth. 

Radishes will also appreciate the partial shade that bush or climbing beans offer, providing protection in the midday sun.

Tomatoes: Growing tomatoes with radishes has lots of benefits. Tomatoes have a strong scent which can help deter pests from attacking radish plants. Tomato plants naturally tower over ground cover plants providing dappled shade during hot periods. The roots of tomato plants will also loosen the soil around radishes allowing radish plants to swell. 

Herbs and Flowers

Borage: The strong fragrance of borage is known to keep pests away from radish plants and help prevent attacks. Borage flowers are also a magnet for pollinators and beneficial predatory insects. Their height as they mature also provides shade protection during hot periods.

Herbs and Flowers

Nasturtiums: Planting nasturtiums close by to radishes helps to keep aphid attacks to a minimum. They tend to be used as a trap crop, attracting aphids to themselves and away from the valuable radish plants.

Dill: Growing dill with radishes attracts predatory insects such as ladybugs and hoverflies which helps keep aphid numbers down, reducing the risk of radish plant damage. 

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Bad Companion Plants for Radishes

Conversely, there are plenty of bad companion plants for radishes which are best to avoid. Here are some examples of those that should be planted as far away as possible from your radish crop:

Fennel: Although fennel is attractive to many beneficial pollinators, it does not make a good companion plant for radish and is known to stunt the growth of many plants thanks to the substance it secretes into the soil from its roots.  

Kohlrabi: Kohlrabi is a very greedy feeder and will work in direct competition with radishes resulting in stunted growth of one or both plants.