How to grow a peanut plant

The peanut (Arachis hypogaea) is a leguminous perennial plant native to South America that’s usually grown as an annual in the UK. Technically, peanuts are not actually nuts as the plant belongs to the Fabaceae (pea and bean) family. Peanuts are commonly referred to as groundnuts, earthnuts, or monkey nuts.

The common name 'groundnut' comes from the unusual habit of the plant burying its pods in the ground. Known as 'pegging', the plants develop adventitious roots that anchor or 'peg' the flowers into the ground, and the pods develop in the soil.

While not native to the UK, peanuts can still be grown successfully in some parts of the country, particularly in warmer regions (and/or indoors) and with the right care. They're best grown in pots in the greenhouse or conservatory, but you may have some success outdoors in warmer regions in summer.

How to grow peanuts

Grow peanuts in well-drained, slightly acidic soil, in a sunny and sheltered spot. They can be grown in pots or directly in the ground, but they require space for their underground pegging process. Harvest after around four months, after the plants have yellowed and died down.

Where to grow peanut plants

Peanut plants require warm temperatures and need a long growing season of at least 120 to 150 frost-free days to mature properly. Therefore, they are best suited to warmer regions in the UK, such as the southern parts of England and Wales. In colder regions, peanuts may struggle to produce a successful harvest due to the shorter growing season, however you can get around this by growing them in a conservatory or greenhouse.

Peanuts can be grown in the ground or in containers, depending on your preference and available space. If growing in the ground, choose a well-drained spot that gets plenty of sunlight. If your soil is heavy clay, lighten it first by adding plenty of compost or horticultural grit. Avoid areas prone to water logging, as peanuts do not tolerate waterlogged conditions. If growing in containers, make sure the containers are large enough to accommodate the pegging process, as the developing peanuts need space to grow underground.

How to plant peanut seeds

Plant peanuts in late spring or early summer once all risk of frost has passed, and the soil has warmed up. However, you can bring the season forward by planting in pots undercover from March. Choose plump, unshelled raw peanuts – if they have been roasted or boiled they won’t grow.

Plant peanut seeds 3-5cm deep, with a spacing of 30-45cm apart. Water well and allow to drain, and then keep the soil evenly moist throughout the growing season.

Peanuts can also be grown from plugs and young plants. Plant these from May in a large container (at least 45cm deep and 45cm across). Water daily in warm weather.

Watch Rachel de Thame plant peanuts in pots for children:

How to care for peanut plants

• As the peanut plants grow, they will send out runners that will eventually peg and bury the pods into the soil. To support this process, place a layer of straw or mulch around the base of the plants to help keep the soil moist to enable the pegs to enter the soil easily
• Water regularly to keep the soil moist but not waterlogged. Avoid overwatering, as it can lead to rotting of the pods and roots
• Peanuts don't require heavy feeding, as they can fix nitrogen in the soil. However, you can apply a balanced fertiliser when planting to provide essential nutrients for growth
• Keep the area around the peanut plants free from weeds, as they can compete for nutrients and water. Regular weeding will help the peanut plants grow more effectively
• Once the peanut plants start to flower, you can remove some of the blooms to encourage better pod development. Removing excess flowers will allow the plant to put more energy into developing larger and more mature pods

How to harvest peanuts

Peanuts are ready to harvest 120-150 days after planting, by which time the foliage should be wilted and yellow. Once the plant has fully wilted, carefully dig up the entire plant, taking care not to damage the peanuts. Shake off any excess soil and lay the plant somewhere away from the rain with good air circulation to dry for a fortnight.

After the peanuts have dried, gently remove the pods from the plant. You can do this by gently pulling the pods away from the plant or by using scissors to cut the pods off. Once you have harvested all the pods, store them in a dry and well-ventilated area for a further two weeks, to cure. After this the peanuts are ready to eat.

How to propagate peanut plants

After harvesting, save some peanuts to sow the following year. Once dried, keep the peanuts in a tin or plastic box in a dry, dark, cool spot such as your garden shed. Sow the following spring as you would normally.

Pests and diseases

Peanut plants are relatively resistant to pests and diseases, but some common issues may still affect them. Regularly inspect your plants for yellowing leaves, distorted growth, or presence of pests such as aphids, and take appropriate measures if necessary.

Signs and solutions include:

• Tiny creatures spinning tiny webs near bleached leaves on a weakened plant – these are red spider mites. Mist the plant to keep the infested area damp
• Soft brown patches on the leaves – this is fungal leaf spot and can be prevented by ensuring proper drainage and avoiding overhead watering
• Distorted or yellowing leaves, stunted growth, sticky honeydew residue and black sooty mould are caused by aphids, which you will be able to see in dense clusters on plant stems and leaves. In small numbers they pose no problems but large numbers can distort growth. Blast them off with a jet from your hose or leave them for ladybirds and other natural predators to find
• Small black flies around the plant (indoors only) are fungus gnats which thrive in damp soil. Avoid overwatering and/or use a mulch such as grit on the soil surface to stop them in the first place
• Another, much larger ‘pest’ is the squirrel, which is known to dig up and eat developing peanut pods. To protect your peanut plants, use physical barriers such as netting or wire mesh. Alternatively, you can also try using natural repellents like chilli powder or garlic spray to deter squirrels from the growing area