Flowers of moss rose last only a day

Is this the mini rose plant? I bought it during Chinese New Year and it was blooming beautifully. After about a month, it stopped blooming and never flowered again. It is growing well with more leaves and many tiny buds, but the buds never grow into full roses. The tiny roses disappear in a day or two. Why is this happening? I put the plant on the patio, which is exposed to rain and sunlight.

Peggy Quay

The plant is commonly called the moss rose and its botanical name is Portulaca grandiflora.

The moss rose plant needs to be grown under direct sunlight for best results. Do note that the flowers last only a day after they open. The flowers tend to wilt in the heat of the day or get damaged by heavy rain.

Check for mealy bugs, which are a common pest in this plant. They can set the plant back if left unchecked.

Kangkong is infested with spider mites

I have been growing kangkong in pots in my balcony. They get six to eight hours of sunlight and the area is fairly windy. They have been growing well and flowering. I harvested some for cooking and the plant produced new shoots just below where I had cut them. Recently, the plant showed brown patches. Is it still safe to eat? Is there a treatment for the issue?

Leong Chung Yan

It appears that your kangkong plant is infested with spider mites, which are minute sap-sucking pests. They look like small, red dots on affected leaves.

These pests are attracted to plants that are under stress, such as when plants are grown in a dry and windy site.

You can help to improve the plant's health by growing it in a more suitable location where it is more humid and less windy. A strong plant is believed to be able to ward off pest attacks better.

Spider mites can be controlled by regular applications of neem oil, summer oil or a matrine-based organic pesticide which you can purchase via online shopping platforms. Repeated applications that cover all parts of the plant are needed to keep the pest infestation low.

The plant is still safe for consumption.

Pandan serani has no scent but dyes food a vivid green

I have two plants that are supposed to be the pandan serani. I want to use the extract of the plant to obtain the natural green colouring for my pandan cakes. Which of these is the correct pandan serani?

Phung Boo Suan

The two plants are different forms of Dracaena reflexa.

The one that has narrower and slightly curly leaves (above, left) appears to be grown as an ornamental plant locally.

I have been gifted a pandan serani plant (also known as Daun Suji) and it resembles the other form (above, right) that you have, which has broader and flat leaves. It is less commonly seen in Singapore.

The leaves of the latter plant yield a vivid natural green dye that is used as a food colouring in Indonesia.

Unlike the fragrant pandan plant (Pandanus amaryllifolius) that is commonly used here for culinary purposes, the pandan serani leaves have no scent.

• Answers by Dr Wilson Wong, an NParks-certified practising horticulturist, parks manager and ISA-certified arborist. He is the founder of Green Culture Singapore and an adjunct assistant professor (Food Science & Technology) at the National University of Singapore.

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