How to grow cucamelons

Cucamelons (Melothria scabra) are a unique and fascinating fruit also known as Mexican sour gherkins or mouse melons. Despite their name, they're not a cross between cucumbers and watermelon plants, but rather a distinct plant within the cucumber family. They are native to Mexico and Central America, where they’ve been cultivated for centuries.

Cucamelons are small, grape-sized fruits that resemble tiny watermelons and have a tart, citrusy flavour. They’re incredibly refreshing and can be eaten raw or used in a variety of culinary applications, such as pickling, salads and garnishes. Cucamelons are also rich in vitamins and minerals, making them a healthy addition to your diet.

While cucamelons may not be as commonly grown as other garden plants, they are gaining popularity among home gardeners for their distinctive taste and appearance. They're easy to grow and require minimal maintenance.

Cucamelons are typically grown as annuals, but they can be grown as perennials in warmer climates (and can be overwintered indoors). They need warm temperatures and are sensitive to frost, so they should be planted out from May, after all risk of frost has passed. If grown in a greenhouse they can be started off earlier.

How to grow cucamelons

Grow cucamelons in moist, well-drained, fertile soil in full sun. Sow seed under cover from March and plant out after all risk of frost has passed. Water regularly and fertilise with a high-potash liquid feed every week or so once flowers start appearing. Harvest cucamelons when they are around the size of a large grape and still firm.

Where to grow cucamelons

Grow cucamelons indoors or outside, in containers or directly in the ground. They are climbers and so require support from a trellis or wigwam of canes.

How to plant cucamelons

Cucamelon seed needs a temperature of around 23ºC to germinate successfully, so sow seed in a heated propagator from early April if they are to be grown in a greenhouse, or from mid April to early May if they are to grow outside. Sow seeds into trays or modules of peat-free seed compost and cover with 7mm-1cm of compost. Firm gently and water with a watering can with the rose attached. As with other members of the cucumber family, it's best to plant the seeds on their sides to reduce the risk of them rotting.

Once the seedlings have reached a height of about 6cm they can be transplanted from trays into individual 9cm pots containing peat-free multi-purpose compost, and grown on for a few weeks until they are large enough to be planted outside, after all risk of frost has passed. If you sowed cucamelon seed into modules you will need to move them into pots a little later, so the rootball stays intact.

Cucamelons are capable of thriving in all types of containers, and even growbags. Make sure pots are at least 30cm across and 30cm deep, and are positioned in a warm, sunny area.

Support the plants on a trellis or wigwam system as you would with cucumber plants. It may also be worth cutting back some of the floppy top growth just before planting; this will soon be replaced by vigorous new growth that is better equipped to grow into the supports. Place a short length of bamboo next to each one - this will help the plant to climb up into the supports. You may need to protect the young plants from slugs and snails.

How to care for cucamelons

Water cucamelons regularly to keep the soil consistently moist but not waterlogged. They also benefit from regular feeding with a balanced fertiliser, and a potash-rich one once they start flowering and fruiting. While cucamelons do not require pruning, it's best to trim off any dead foliage to improve air circulation and reduce the risk of diseases.

Fruits start to ripen from July. Pick them at regular intervals to stimulate the growth of more flowers and fruits.

How to harvest cucamelons

Harvest the fruits when they are about the size of a large grape but still firm to touch. Simply twist or cut the fruits from the vine, being careful not to damage the plants. Avoid letting cucamelons ripen too much on the vine as they can lose their crisp texture.

Cucamelons are best eaten straight away but you can store them in a perforated plastic bag or a container with a lid for just over a week in the fridge. Avoid washing cucamelons before storing them, as the moisture left on their surface can cause them to spoil more quickly. You can also freeze cucamelons: simply wash and dry the fruits, then spread them out in a single layer on a baking sheet and freeze until firm. Once frozen, transfer them to airtight containers or freezer bags and store in the freezer for up to three months. Frozen cucamelons are best used in cooked dishes as their texture will change after freezing.

How to propagate cucamelons

Cucamelons can be propagated from seed or tubers. To propagate from seed, simply allow a few fruits to fully ripen on the vine until they turn yellow or brown and start to soften. Cut them open and scoop out the seeds inside, then rinse them thoroughly in a sieve to remove any pulp or debris. Spread the seeds out on a paper towel and allow them to air-dry thoroughly, before storing in a consistently cool, dry place in a labelled envelope or airtight container.

You can also propagate cucamelons from tubers, much like dahlias. Wait until the plant has been hit by the first gentle frost, then use a garden fork or shovel to gently dig around the main stem to find the tubers, which may be quite deep in the soil. Be gentle when handling to avoid damaging them. To store the tubers, add some potting compost to the bottom of a 35cm pot and place the tubers on the surface, covering them completely with more compost. You can layer the tubers with more compost until the pot is full, if you need to. Then store the pot in a cool, dry and frost-free spot for winter, and replant next spring.

Pests and diseases

Cucamelon plants are relatively resistant to pests and diseases. However, they may sometimes be affected by powdery mildew or aphids.

To prevent powdery mildew, water at soil level to avoid getting the foliage wet, and allow plenty of air circulation around the plant.

Aphids are a natural part of the garden ecosystem and are eaten by several species of birds, ladybirds and lacewings. However, in large numbers they can be removed by spraying the affected areas with a strong jet of water or by manually crushing the insects (bear in mind you will almost certainly be killing some of their insect predators, too).