Root awakening

Ephemeral hibiscus
Ephemeral hibiscusPHOTO: JOHN CHUA

Ephemeral hibiscus

I was told this flower belongs to the hibiscus family. Why does it bloom for only a day before withering and dropping off? How can I make it bloom for a few more days?

John Chua

The longevity of flowers largely depends on the plant's floral characteristics. Hibiscus flowers are often described as ephemeral as they are known to last for not more than a day. They are highly sensitive to exogenous ethylene gas which causes the flowers to fade.

Hence it is important to remove faded or fading flowers promptly and ensure the plant has sufficient air circulation.

Plant for folk medicine

I was told these plants (left) are good for diabetics. But Google search results mentioned that the plants are toxic. What is its actual name and what are its medicinal effects?

Paulene Chan

The medicinal herb is botanically known as Gynura procumbens. Locally, it is grown for its folk medicinal uses and is used to treat diabetes, high-blood pressure and cholesterol. The leaves are eaten as a vegetable.

More in-depth and scientific studies need to be done on humans before conclusions can be made regarding its health benefits. Currently, studies of this plant have largely been conducted on rats

Sour fruit to flavour food

I saw these trees in Telok Blangah Hill Park. Some older folks say the fruit (left) are edible and can be made into a drink. What is this tree?

Johnnie Chia

It is commonly known as Asam Gelugur or Asam Gelugo. Its botanical name is Garcinia atroviridis and it belongs to the mangosteen family (Clusiaceae). The fruit, even when ripe, are extremely sour. They are more commonly sliced, dried and used to flavour curries and soups.

•Tip: Give bare garden patches a break

The bare patch in your garden could be caused by heavy and frequent foot traffic. This compacts the soil and impedes lawn recovery and growth. You may need to regulate foot traffic over the area and let it "rest". Consider spiking the patch to aerate the soil to let the roots have space to grow and, at the same time, let water and air penetrate the root zone. Fertilise the patch to aid growth.

Pesticides: Chemical versus natural

My edible plants such as chilli, lime and curry are infested with mealy bugs; root pests such as root mealybugs; white, crawling insects and snails. Should I spray the plants with pure organic neem oil to get rid of them? What else should I do to wipe out the infestation?

Caroline Lee

Plants get infested by pests if they are not grown under optimal conditions. They must be given sufficient space and sunlight. Avoid over-using fertilisers rich in nitrogen as this promotes luxuriant foliage growth that attracts these pests in some plants.

For sucking insect pests, use neem oil which is available from nurseries for garden use. Such products have an emulsifier added to aid dissolution in water.

Neem oil is safer than chemical pesticides to use on edible plants. Make sure you spray the entire plant thoroughly with it. Weekly applications may be necessary to keep a lid on the pest populations.

As for eliminating root mealybugs, drenching the soil with chemical pesticides such as cypermethrin may be the only effective option. Make sure you follow the label instructions and adhere to the withholding period that needs to elapse before harvesting can be done safely.

For snails, you may want to set up traps in the night with bait. The trapped snails can be disposed of the following day. For the traps, you can use an upturned pot with bait made of cabbage leaves or other plant material the snails love to feed on.

•Answers by Dr Wilson Wong, a certified practising horticulturist and founder of Green Culture Singapore (www.greenculturesg. com). He is also an NParks-certified park manager.

•Got a gardening query? E-mail it with clear pictures, if any, and your full name to

A version of this article appeared in the print edition of The Straits Times on July 04, 2015, with the headline 'RootAwakening'. Print Edition | Subscribe