How to Grow Cucamelon (Mexican Sour Gherkin)

Many beautiful vegetables can grow in your garden, but if there is one that deserves to be called cute, it’s the cucamelon. It’s not difficult to see why they are also called mouse melons: The one-inch fruit looks like a watermelon that a mouse would lug home from the market. Botanically, the cucamelon (Melothria scabra) is neither a cucumber nor a melon, though it is part of the larger cucumber family (Cucurbitaceae).

A fast-growing, vining plant, the cucamelon is a frost-tender plant. While it is perennial in tropical climates, it is most commonly grown as an annual in other climates, where it is planted in the spring. Small yellow flowers appear in the late spring to early summer and are followed by the striped green fruits, which are about the size of a large grape. The flesh of the fruits is white. Cucamelons have a unique crunch and a cucumber-like but slightly tangy flavor.

How to Plant Cucamelon

When to Plant

Cucamelons are usually direct-sown in the garden after all danger of frost has passed in the spring and nighttime temperatures are 50 degrees Fahrenheit. The seeds germinate and sprout in 10 to 14 days and reach maturity in 60 to 70 days days.

Selecting a Planting Site

A sunny spot with well-draining soil is key for growing cucamelons. Container growth is also an option. Make sure no nearby taller plants will shade the cucamelons as plants leaf out in the spring.

Spacing, Depth, and Support

Plant seeds about 1/2 inch deep, and space plants roughly two feet apart. Cucamelons don't take up nearly as much space as other vine vegetables, but it's still a good idea to grow them on a trellis or other support structure because it keeps the fruit off the ground where it can rot in humid weather.

The vines are very tender and are easily injured. So if you grow cucamelons on a trellis, it's easier to spot the fruit for harvesting without disturbing the vines. Round tomato cages, tomato trellises, or tomato towers also work well for supporting cucamelons.

Cucamelon Plant Care

Light

Cucamelons grow best in full sun, meaning at least six to eight hours of direct sunlight on most days. But they can tolerate a bit of shade and might appreciate some afternoon shade in hot climates.

Soil

Cucamelons prefer to be grown in well-drained humus-rich soil. They like a slightly acidic soil pH. And as with most vegetables, they benefit from the addition of organic matter to the soil. So work some compost into the soil before planting, especially if the soil isn't fertile. Mulching helps to keep the soil moist and maintain an even soil temperature. Spreading a layer of mulch also helps to keep weeds under control. Cucumelons have shallow roots; the less you need to weed around them, the less chance there is of damaging the plant.

Water

Cucamelons prefer moist but not saturated soil, so make sure your plants receive one inch of water per week, including rainfall. If you need to provide supplemental water, using a soaker hose or drip irrigation is ideal. If you water by hand with a hose, make sure to direct the water to the base of the plant so that it soaks down to the plant roots. If you have to water with overhead sprinklers, do so early in the morning so that the foliage can dry before nightfall. Wet foliage encourages fungal diseases; fungus does not grow on dry foliage.

Temperature and Humidity

Cucamelons are frost-sensitive and thrive best a warm, humid climates that approximates their native setting in Central America. The seeds will not germinate in soil below 60 degrees Fahrenheit. These plants prefer high humidity levels rather than arid conditions.

Fertilizer

When they are three to four weeks old, fertilize seedlings with a starter fertilizer solution: a balanced fertilizer 1/4 of the strength indicated on the label. Another light fertilization in the midsummer will help to promote fruiting.

Pollination

Cucamelons self-pollinate from male and female flowers on the same plant with the help of the wind and garden pollinators.

Types of Cucamelon

Cucamelon is a unique heirloom plant with no cultivars or hybrids developed.

Cucamelon vs. Cucumber

Cucamelons look a lot like tiny cucumbers, and they have a similar flavor. But there are some clear differences. Cucamelons have a slightly rounded appearance while cucumbers are more elongated—not to mention that cucamelons are significantly smaller than cucumbers. Flavor-wise, cucamelons taste quite similar to cucumbers except they have a hint of lime-like tartness.

Harvesting Cucamelon

Harvest cucamelons when they are no more than one inch in diameter. If you let them grow larger, they will become seedy and much less palatable. Make sure to check for ripening fruit at least every other day, starting around 60 days after planting. To avoid damaging the vines, cut the fruits off the vine with snips or scissors rather than pulling off by hand.

Cucamelons keep well for a few days in the vegetable crisper of the refrigerator. They can be used in a variety of ways, including slicing to add to salads, chopped and added to salsa, or pickled and canned. They even can serve as a garnish for drinks.

How to Grow Cucamelon in Pots

If you don't have the garden space for cucamelons, growing them in a container paired with a trellis is a great option to maximize your vertical space. Unlike other vegetable vines, cucamelons are relatively lightweight even when loaded with fruit, so there is less risk of the container toppling over. Use at least a five-gallon container with drainage holes. An unglazed clay container is a good option because it will be sturdy and allow excess soil moisture to escape through its walls. Plant only one cucamelon plant per container.

Pruning

Pinch back the tips of vines in the spring and early summer to encourage more branching, which will result in more flowering and fruiting.

Propagating Cucamelon

An easy and inexpensive way to propagate cucamelons is simply to save seeds from the fruits. Here’s how:

1. Leave a few fruits on the vine at the end of your growing season until they are overripe and yellow. 
2. Remove the overripe cucamelons from the vine, and cut them in half.
3. Scrape out the seeds and pulp. Discard the pulp, and put the seeds in a jar of water for one to two days. 
4. Dispose of the debris and any seeds that have floated to the top of the jar. Remove the other seeds, and rinse them. Then, let them dry thoroughly in a single layer.
5. Store the seeds in a sealed paper packet in a cool, dry spot. Sow them within a year for best results. 

How to Grow Cucamelon From Seed

Cucamelons can be slow and erratic to germinate. You can direct-sow seeds after the threat of frost has passed or start them indoors around three to four weeks before your projected last frost date. Use biodegradable pots to avoid disturbing the tender roots when you transplant the cucamelons into your garden.

Plant two to three seeds per pot about 1/2 inch deep in sterile seed-starting mix. Keep the soil moist and at a temperature of about 70 degrees Fahrenheit. It can take up to 14 days or longer for seeds to germinate, so be patient.

After the seedlings emerge, thin them to one plant per pot. When the seedlings are at least two inches tall, harden them off and then transplant them into your garden or into a container after all danger of frost has passed.

Potting and Repotting Cucamelon

Use a quality all-purpose potting mix when potting cucamelons. It's best to plant them in a container that will accommodate their mature size, as repotting can be damaging to the roots and the vines.

Overwintering

Because cucamelons are tender plants, they are typically grown as annuals, so overwintering isn't necessary. However, it is possible, though not always successful, to keep a container cucamelon plant indoors for the winter and bring it outdoors in the spring. Bring it indoors before the first fall frost, and water just so the soil doesn’t dry out completely. Bring the plant outdoors the following spring once frost is out of the forecast, and resume watering as usual.

Common Pests and Plant Diseases

Cucamelons are relatively healthy when compared to similar vining plants. Powdery mildew is the most common disease, but it is rarely serious. Good air circulation and careful watering to avoid splashing soil spores onto the foliage will help to prevent mildew. Aphids can also affect the plant; organic remedies include citrus oil or insecticidal soap.