Root Awakening: Croton plant may be lacking in water and infested by mealy bugs

Croton plant may be lacking in water and infested by mealy bugs.
Croton plant may be lacking in water and infested by mealy bugs.PHOTO: KOH MONG CHUA
Leafy rose cactus has attractive flowers.
Leafy rose cactus has attractive flowers.PHOTO: CHUA SWEE CHYE
Cat Tails Euphorbia is best grown under direct sunlight.
Cat Tails Euphorbia is best grown under direct sunlight.PHOTO: HELEN LOH
Palms should not be topped, but need checks on structural integrity.
Palms should not be topped, but need checks on structural integrity.PHOTO: K.L. CHAN
Grow Coconut Magnolia in a pot to manage its size.
Grow Coconut Magnolia in a pot to manage its size.PHOTO: FRANK ELISSEN

Croton plant may be lacking in water and infested by mealy bugs

I have been keeping this croton for a few months and now it looks unhealthy and has some white fungus. What should I do?

Koh Mong Chua

The new leaves of your croton plant (botanical name: Codiaeum variegatum) are wilting and this could be a sign that it is lacking water.

Plants grown in pots will need to be watered regularly and thoroughly to keep the root zone moist at all times. The soil dries out quickly when plants are grown in a sunny and/or windy area.

When plants are stressed, they can become prone to pest attacks.

The cottony mass seen on your plant could be mealy bugs, a type of sucking insect pest. If attacked in large numbers, the plant can be weakened and die eventually.

To solve the issue, you can first use a jet of water to wash off adult pests. Then spray a solution of summer oil or neem oil pesticide on all parts of the plant - it acts by suffocating this pest. Repeated applications are needed to keep the pest population in check.

Always inspect the plants regularly and manage infestations, as doing so reduces the likelihood of them spreading and becoming more severe.


Leafy rose cactus has attractive flowers

I saw this plant growing by the road in Geylang. The stems have sharp thorns and the flowers are pink and come in bundles. What plant is it?

Chua Swee Chye

The plant is commonly called the rose cactus and its botanical name is Pereskia grandifolia.

It is a relative of the "Seven Star Needle" (botanical name: Pereskia bleo), which is commonly grown in the medicinal plant section of community gardens.

This plant is a leafy cactus that grows into a shrub or small tree with prickly stems. It produces ornamental pink flowers.

It should be grown in a moist and well-drained site and should not be allowed to dry out excessively.

Propagation is via stem cuttings.


Cat Tails Euphorbia is best grown under direct sunlight

I have had this plant for about five years. It has been growing long stems and is getting a little tangy and heavy. Can I prune the new shoots? What plant is this and how can I take care of it?

Helen Loh

The plant is commonly called the Cat Tails Euphorbia and its botanical name is Euphorbia alluaudii.

It is likely a crested form as seen in the lower, mutated portion of the plant, where the stem grows into a flattened and wide structure.

You can prune the long stems to keep the plant tidy.

Note that the sap of the Euphorbia is toxic and should neither be ingested nor come into contact with your skin or eyes.

In an apartment setting, the plant is best grown with at least four to six hours of direct sunlight to achieve a more robust and compact growth habit.

Its growth media should be moist but well-draining. It should not be allowed to dry out excessively.


Palms should not be topped, but need checks on structural integrity

I have three foxtail palms at the frontage of my house which have grown to a height of more than 10m over the last 15 years. How can I manage the trees when they grow too tall? Is there a risk in leaving the trees to grow or should topping be done?

K.L. Chan

Palms are not trees.

In trees, when their branches are pruned, new growth can emerge as new branches. When a palm's trunk is cut off, as there are no dormant buds on it, new branches are not produced and the palm will die.

Given the height of the palms, you will likely need to hire the services of a landscape company to remove yellow fronds as well as inflorescences and fruit. If left on the palms, these can fall and pose a hazard.

In the long term, look out for abnormalities or decline in terms of the palms' growth, such as abnormal yellowing on the growth of the fronds, a reduction in growth vigour or any injury on the trunks.

You should consult a certified arborist from a landscape company who will perform an on-site examination to assess the health and structural integrity of the palms.


Grow Coconut Magnolia in a pot to manage its size

I have had this potted plant for many years and it is slowly degenerating. I plan to transfer it into a larger pot. What plant is this and how do I take care of it?

Frank Elissen

The shrub is called the Coconut Magnolia (botanical name: Magnolia coco) and produces scented flowers.

This plant thrives in a semi-shaded location and can be grown in a pot to manage its size or planted into the ground where it grows into a tree.

It prefers growing media that is moisture-retentive, well-draining and which should not be allowed to dry out.

• 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.

A version of this article appeared in the print edition of The Straits Times on October 12, 2019, with the headline 'Root Awakening'. Print Edition | Subscribe