How to Grow Gac - The Secret Super Food

The term “superfood” gets thrown around a lot these days, but sometimes there’s merit to the hype around a particular fruit or vegetable. That’s definitely the case with “gac,” a vivacious, red-when-ripe tropical fruit loaded with nutrients. Find out how you can grow gac, and why the Vietnamese refer to it as “the fruit from heaven.”

Health Benefits

Gac fruit has an abundance of phytonutrients, vitamins, and minerals. It has 70 times more lycopene than tomatoes (lycopene is a cancer-fighting antioxidant responsible for the red pigment in some ripened fruits and vegetables). Gac also has 10 times the amount of beta-carotene of carrots and sweet potatoes (more carroty than carrots!), and the Omega-3 fatty acids in its pulp make that substance extremely bio-available for absorption into the blood stream. Beta carotene is converted into vitamin A, which promotes healthy immune systems, glowing skin, and sharp vision.

In southeast Asian regions like Vietnam and southern China, where the gac plant grows naturally, many cultures make use of these carotenoids in traditional medicine, specifically for treating dry eyes and ocular disease. The fruit also boasts 100 times more zeaxanthin than carrots, another major contributor to eye health – making gac an especially useful superfood for anyone who suffers digital eye strain from too much screen time. Other prominent nutrients include vitamins E and C, magnesium, manganese, zinc, selenium and various polyphenols and flavonoids.

In short, this fruit is very, very good for you. So why don't you ever see it in your supermarket?

Green, spiked gac melons hang from a trellis.

Growing Conditions

The answer is that if you don’t live in a region where the gac plant thrives naturally (like Southeast Asia, Southern China, and Northeast Australia) it takes a bit of work to get growing conditions just right. This is especially true if your growing zone experiences frost or cool temps. Areas that share temperatures close to those of tropical climates (zone 9 and above) have the best chance at supporting a good harvest, but an experienced or determined gardener may be able to create mock environments that yield healthy fruit.

Once the vine is established, it will only remain as a perennial plant if kept protected from cool nights and frost, so if you live in a chilly region, a greenhouse may be the only option. Alternatively, it can be grown from seed each year, though this approach requires careful planning.

How to Grow Gac Melon

Start your plants from seed at least eight to 12 weeks before moving them outdoors. Be patient—the seedlings are known to take a long time to germinate. Soak the seeds overnight to help the process along, and when it's planting time, remember to place the seeds opening-down into the dirt or pod so their vines can start growing in the right direction.

The gac vine is dioecious, which means male and female reproductive systems or flowers grow on separate plants—so, it’s a good idea to sprout at least six plants to ensure pollination between male and females. Once they start growing, replant your seedlings into a five gallon pot before planting outdoors or in a greenhouse. Always make sure your plants have plenty of sun, and when moving them outside, give them a healthy amount of space to flourish.

It will take approximately eight months from germination for a vine to bear fruit, as long as temperatures stay around 60 degrees Fahrenheit and above. The harvest window is quite short (only two months once a year), but one plant can yield 30-60 fruits, depending on its age and growing conditions.

Gac Flowers

Gac vines will produce pale, yellow flowers around two to three months after they're planted. If you have a good balance of male and female plants, natural pollination from insects should be enough to get them started. Hand pollination may help nudge things along, though that method requires that you identify the sex of your flowers properly. A male gac flower has frilly petals that droop openly, whereas the female flower has pointed, triangular flowers with cleaner edges. Fruits will be ripe enough for harvesting around five months after flowering.

A yellow flower blooms on a gac vine.

Alternative Gac Propagation Methods

An alternative to starting gac from seed is planting root tubers or cuttings from a vine. This method can be more reliable than using seeds, but the materials are harder to come by, unless you have access to mature plants. With tubers and cuttings, unlike seeds, you have the benefit of knowing the individuals plant’s sex.

Expert gardeners can try grafting female material onto the main shoot of an unneeded male plant to see if it can self-produce. New studies in hybridization suggest it may be possible to produce bisexual gac flowers in the future, eliminating some of the fruit's growing pains.

Plant Care and Characteristics

The gac fruit grows on large, woody vines, like oversized cucumber plants, and will be happiest with the support of a strong trellis, fence, or arbor. The vines can stretch up to 20 feet long, and the fruit can grow to be as big as cantaloupes, so it needs plenty of space. When the melon is ripe to pick, it turns bright red and feels soft under its hard, spiny, avocado-like casing when pressed gently.

Gac is in the melon family, and has a soft, spongy flesh with large, oily seeds. Though vibrant in color, it has a mild flavor, sometimes compared to a cucumber. In traditional Asian cuisines, it is often cooked with rice to add color and a nutty taste, not to mention a boost in nutrients. Because of its short harvest time, it is often used in ceremonial dishes. Don't eat the outer shell or rind. Besides being intimidatingly pointy, it's toxic and can make you sick.

Gac is a unique "super fruit," and it's appearing increasingly in Western diets because of its significant health benefits. While it might take a lot of patience to learn how to grow gac in non-tropical regions, it could also be well worth the effort. It'll do your body good, and make an impressive visual addition to your garden or greenhouse. Your friends, family, and fellow DIYers will be curious to hear how you pulled it off.

We're curious too! If you have experience growing gac, tell us about it in a comment below, or share your process on our Projects page.