Fruit vegetables
Cucamelon
Melothria scabra
Timings for your region
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Start indoorsearly April – late April
Plantingmid May – early June
Harvestearly August – early October
Practical tip
The fruits are ripe at two to three centimetres and taste like a cucumber with a squeeze of lime — any larger and they just go mealy. Pick through every few days and the vine keeps setting more.
Origin & history
Despite the name, the cucamelon is not a cucumber but Melothria scabra, a genus of its own within the cucurbit family. It was grown in Mexico and Central America long before the Spanish conquest; in Spanish it is sandiita, little watermelon, after the mottled skin. It has only been in European seed catalogues for about fifteen years. At home it is perennial: it forms a tuber underground and shoots from it again the following year — here that tuber rarely comes through a winter outdoors.
Varieties
There is effectively no choice of variety: what you buy is the straight species, just under half a dozen names — cucamelon, mouse melon, Mexican sour gherkin, sandía de ratón. What matters is not picking up the wrong plant: the West Indian gherkin (Cucumis anguria) carries spiny, egg-sized fruit, and the horned melon (Cucumis metuliferus) is larger again. The seed is open-pollinated, so you can save your own from a well-ripened fruit. The grains are hard and take one to two weeks to germinate at 22 to 25 degrees; leave old packets alone.
Care
It wants to go upwards from the start: a net, a panel of fence or a few taut strings. Tie the first two shoots in by hand; after that the tendrils hold on by themselves. Nothing gets pinched out. It drinks less than a cucumber, but a 10-litre pot still runs dry in a day in high summer, so check daily. Feed sparingly or you get three metres of vine and very little fruit. In October you can lift the tuber, store it dry and frost-free at 8 to 10 degrees and pot it up in April — it then starts weeks ahead of a sowing.
What can go wrong
Nothing happens for weeks, and that is not a fault: the cucamelon is monoecious, with male and female flowers sitting separately on the same vine, and at first almost only male ones open. You recognise a female by the tiny fruit behind the flower. Insects do the pollinating; on a glazed balcony where nothing flies, move the pollen across with a soft brush in the morning. Otherwise little goes wrong — slugs on the young plants are the biggest risk, and mildew in September costs only the last few fruits. Fruit you miss self-seeds, and in a mild winter the odd tuber survives in the ground.
Harvest, storage & kitchen
In a bowl at room temperature they keep about a week, unwashed in the fridge drawer a little longer; freezing does not work, they collapse on thawing. The real answer to a vine carrying several hundred fruits is pickling: whole, with dill, mustard seed and a mild vinegar brine, they stay crunchy for months and go nowhere near as soft as gherkins. Raw and halved they go into a salad, into a salsa with tomato and coriander, or onto a cheeseboard. Nothing needs peeling; the skin is thin and does not catch between your teeth.
All timings are guide values for the given climate, not a guarantee. Weather, aspect and variety all have a say.