Underground edible plants to grow for Chinese New Year

SINGAPORE – In anticipation of Chinese New Year on Feb 17, a range of seasonal fruit and vegetables with festive significance have appeared in local markets.

Among these are underground edible plants with organs called corms, which store food as starch, and have both scars and growth nodes on their exterior.

A particularly nostalgic plant for me is the Chinese arrowhead (Sagittaria trifolia), also known by the Chinese name “ci gu”.

When I was younger, my mother would buy corms to grow several weeks before Chinese New Year. She buried them in bowls of pebbles, filled these with water and, after some time, arrow-shaped leaves would appear. We would tie red ribbons and hang festive ornaments on the plants.

Like many marginal aquatic plants, the Chinese arrowhead grows near the water’s edge in nature. It is a symbol of progress because of its arrow-shaped leaves, which grow upwards from the corms. Its starchy corms are often thinly sliced and deep-fried as a snack.

Another marginal aquatic plant that has festive symbolism is the water chestnut (Eleocharis dulcis), known by the Chinese names “bi qi” or “ma ti”, the latter of which translates to “horse’s hooves”.

It is a symbol of unity and, in the upcoming Year of the Horse, is said to bring its owner the strength of a horse. Its peeled corms are crunchy and sweet. They are often diced and used as an ingredient in ngoh hiang, a fried five-spice meat roll popular at this time of year.

The water chestnut, like the Chinese arrowhead, grows in bodies of water with corms buried in mud. Its hollow, tube-like leaves emerge from the water.

Both plants can be grown together, as the water chestnut’s fine leaves are a pleasing contrast to the Chinese arrowhead’s larger foliage.

Finally, the yam (Colocasia esculenta), also known as taro, grows here in two varieties: the large yam and baby yam. It can thrive in wet and dry conditions, and produces large, shield-shaped leaves.

Called “yu tou” in Chinese, they are seen as auspicious symbols that bring good fortune. Their peeled corms are used in festive dishes like the fried yam basket, abacus seeds and yam cake.

These three underground edible plants are useful educational tools to learn about plant anatomy. It is worth noting that corms – unlike garlic and onion bulbs – are solid, with no scale leaves or protective tunic (outer skin).

They are distinct from tubers such as those found in potatoes. Tubers are also underground storage stems, but have an elongated form.

Growing auspicious underground edibles 

Both the Chinese arrowhead and water chestnut are imported from China for sale. As such, these cultivars may not be very productive in Singapore’s climate.

In my trials, plants grown from market-bought corms do not produce large corms later, if any at all. They are best suited for short-term display as ornamental plants, rather than for food production.

To grow either of these plants, put a healthy, unblemished corm in a deep bowl of water with rounded pebbles. The pebbles will keep the corm submerged. In a week or two, the corm will produce white roots, followed by foliage. Change the water regularly to prevent mosquito breeding and replenish dissolved oxygen.

Once leaves appear, move the bowl to a location where the plants can get at least four hours of direct sunlight a day, such as on a windowsill.

Ensure the bowl is protected from wind and not in danger of falling, as the Chinese arrowhead and water chestnut’s leaves are spongy and fragile. Staking may be necessary.

The food stored within the corms is typically enough to tide the plants over the festive period. However, without fertiliser for long-term growth, they will decline.

Fertiliser should not be added at the beginning, as exposure to sunlight can lead to algae growth. Once the plants have grown, their leaves are usually large enough to prevent light from reaching the pebbles and water in the bowl. Aquatic plant fertiliser is available in tablet form at nurseries.

You can also plant Chinese arrowhead and water chestnut in large, shallow ponds with soil for aquatic plants. Once they start to grow, they can be moved to bigger water bodies in your garden.

Both the Chinese arrowhead and water chestnut thrive under direct sunlight with regular fertilisation. Hot water will stress them out, so keep them in a large body of water which will not heat up too fast. The Chinese arrowhead must be divided and replanted periodically. Watch out for aquatic snails, which eat the plants’ leaves.

Of these three festive plants, yam is best suited for Singapore’s climate, and is often seen in community and allotment gardens. It can be grown in a pot or in the ground, as long as it has plenty of sunlight and is fertilised regularly.

Place a healthy, unblemished yam corm in a cool location until it produces green shoots. Once that happens, plant it in a well-draining, moisture-retentive soil-based growing medium rich in organic matter.

Yam plants may suffer from minor fungal spots, but infected leaves can be pruned. They are sometimes attacked by caterpillars, but these are easily removed by hand.