How to Grow Cucamelons

cucamelons in a bowl

How to Grow Cucamelons

What’s a Cucamelon? Cucamelons looks like a watermelon but is the size of an olive and tastes like a mix of a cucumber and a lime. It is incredibly easy to grow, can tolerate a lot of neglect (perfect for novice growers!) and at the same time is ignored by most pests whilst producing masses of fruit throughout the summer. As if that wasn’t enough, it is actually a perennial plant that can be stored in the same way as a Dahlia over the winter.


When to sow your cucamelons depends on their final growing place. If you intend to grow them in your heated Harvst S-Series or another heated greenhouse you can start in late winter. April or May is better if you intend to grow them in an unheated Harvst or greenhouse or outdoors. 

Fill a pot, tray or multi-cell tray with peat-free compost and water it. Sow the seeds at least 2cm apart on their sides (not laying flat) and cover with 1cm of compost. Water again carefully! Putting a plastic dome or cling film on top can help germination but make sure it has air holes for ventilation. Keep the soil evenly moist until the seeds germinate, if they dry out they will likely not germinate at all. Having said that, be careful not to overwater. 

Cucamelons will need 20-26°C to germinate well and normally appear within 7-10 days. Once the seedlings appear, remove the plastic and place in a bright location with 12-16hrs of light. 20-24°C is an ideal growing temperature.

Plant care   

Transplant the seedlings to their individual 7-9cm pots when at least one set of true leaves have formed. Do not touch the stem but lift the seedling in its leaf and plant at the same depth as it was. Repot them into slightly larger pots when the roots start to stick out at the bottom. The size of the plant can be restricted somewhat by the size of the pot but aim for a large pot as the final one if you have space. You can also use grow bags or plant into borders but choose a sunny and sheltered spot!

You can keep the pot in your mini greenhouse if you have space, or put it outside when all risk of frost is over. To acclimatise the plants to outdoor conditions, lift them outside in a sheltered, lightly shaded spot during the day, and put them back in at night. Gradually increase the time outside. Do this for about two weeks before leaving them out all the time. 

Keep the compost evenly moist and feed every 10-14 days with a tomato fertiliser. Train the main stem up a vertical support like a wire, string or cane and pinch out the growing tip when it reaches 2.5m, and pinch out the growing tips of the side shoots when they are 40cm long. If your space is limited you can pinch out the tips earlier. 


Cucamelons are ready to harvest when they’re the size of a small grape or olive. They should still be firm and if they’re a bit bitter and soggy, pick earlier next time! 

Watch out! 

Cucamelons are generally problem free!

Pro Tip

In late autumn when it has stopped producing fruit, lift the cucamelon roots and store in barely moist compost in a garage or shed over winter. Plant out again next year.

Nerdy facts

Cucamelons are known as ‘Little mouse melons’ in Mexico where they grow wild. Although they may appear like something new to us, they have been harvested by indigenous people since well before the arrival of European settlers.