Root Awakening

Bathroom too dim for spider plant to grow well.
Bathroom too dim for spider plant to grow well. PHOTO: TAY MEI MEI
Crucifix orchid grows best in a sunny location and in a porous growing medium.
Crucifix orchid grows best in a sunny location and in a porous growing medium. PHOTO: ALISON WONG
Indian rue needs a well-drained medium to thrive.
Indian rue needs a well-drained medium to thrive. PHOTO: TONG K.W
Ulam raja may be infested with broad mites.
Ulam raja may be infested with broad mites. PHOTO: ANG GERK KUAN
Star apple produces edible fruit and has attractive foliage.
Star apple produces edible fruit and has attractive foliage. PHOTO: VINCENT KUMAR

Bathroom too dim for spider plant to grow well

I bought this plant recently and placed it in my bathroom. I saw on a television programme that this plant is said to help absorb odours. But the leaves are turning black. What is wrong?

Tay Mei Mei

The plant is commonly called the spider plant (Chlorophytum comosum). It is a common houseplant that is often advertised to have "air-cleansing" properties, but its efficacy remains doubtful.

The leaves appear to be affected by disease and are sparse and droopy. This may be caused by the lack of sufficient sunlight that is needed for the plant to have healthy growth. The light conditions in the bathroom are often too dim to support plant growth and the lack of light will make a plant susceptible to disease.

The spider plant prefers to be grown under filtered sunlight for at least four hours daily. You may want to move it to a brighter place for it to photosynthesise for several days a week before returning it to the bathroom for display purposes.

Crucifix orchid grows best in a sunny location and in a porous growing medium

What is the name of this orchid growing in my balcony?

Alison Wong

This plant belongs to the genus Epidendrum and is commonly called the crucifix orchid. It is considered an easy-to-grow orchid.

It prefers a sunny location and needs a well-drained and porous medium. Locally, it is usually potted up in charcoal chips which permit fast water drainage and provide ample aeration for the roots.

Ulam raja may be infested with broad mites

I grow ulam raja in a pot. I harvested some leaves recently, pruning the top of the plant. But now, the new leaves look crinkled at the top as well as at the bottom of the stem. What is the right way to prune the plant and how regularly can I harvest the leaves?

Ang Gerk Kuan

Your plant does not appear to be suffering from nutrient deficiency. Instead, it may be infested with broad mites which feed on new leaves and cause them to become deformed.

Do the affected leaves feel stiff and are easily broken apart? The undersides may also appear shiny compared with normal leaves.

Broad mites are commonly found on chilli plants and if you have infested chilli plants nearby, the pests may have been brought over by flying pests such as whiteflies.

Broad mites are microscopic and are not visible to the naked eye.

They can be controlled with neem oil, summer oil or a matrine-based organic pesticide. Repeated applications that cover all parts of the plant, especially the new emerging foliage, are needed to keep the pest infestation under control.

Prune the young leaves regularly. As the plant is an annual, it will die after flowering and seeding for reproduction purposes. By pruning the young shoots regularly, you will help prolong the plant's life.

Indian rue needs a well-drained medium to thrive

This herb gives green bean soup a fragrant and unique flavour. But it is not growing well. What should I do?

Tong K.W.

The plant is commonly known as the Indian rue. Its botanical name is Ruta graveolens and it is grown both as a culinary and medicinal herb.

This plant can be a little challenging to grow in hot and humid Singapore. It prefers a drier climate to thrive. You need to grow it in a porous, well-drained medium as constant wet feet can cause it to rot and die. The roots may need to dry out a little before you water it again.

The plant needs a sunny spot with either direct or filtered sunlight for at least four hours daily.

Star apple produces edible fruit and has attractive foliage

I saw this large tree with fruit near my place. What tree is this and is the fruit edible?

Vincent Kumar

The tree is botanically known as Chrysophyllum cainito. Its common names include star apple, golden leaf tree and milk fruit. It is admired for its attractive leaves with golden-brown undersides.

When cut, the fruit has a radiating star pattern in its cross-section. The fruit, when fully ripe, is eaten as a fresh dessert fruit. It is reported to be sweet and best served chilled.

• 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.

•Have a gardening query? E-mail it with clear, high-resolution pictures of at least 1MB, if any, and your full name to stlife@sph.com.sg. We reserve the right to edit and reject questions.

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A version of this article appeared in the print edition of The Straits Times on July 25, 2020, with the headline Root Awakening. Subscribe