Root awakening

Florist's Gloxinia.
Florist's Gloxinia.PHOTO: ANDREW NAH

Money plant not getting enough water from beads

This money plant is grown in a bottle with water beads to prevent mosquitoes from breeding. I notice that the plant grows less well in water beads - some stalks have turned yellow or there are fewer new shoots. Are water beads suitable for money plants?

Chow Mun Zing

The colourful beads are made of polyacrylamide and are thought to release water slowly for the plant.

From the picture, it appears that your plant may not be doing well as it is not receiving sufficient water, probably from the lack of roots and/or the beads are not releasing water fast enough.

Also, there are safety concerns regarding polyacrylamide beads as traces of its raw material may still be present and degradation products that develop over time may pose a health risk to humans, and the environment, when disposed of.

The good old method of growing some plants in hydroculture may be the way to go - this is where the plant is grown in expanded clay pellets with a water reservoir below. As long as the container is sealed and the water level is way below the surface, the incidence of mosquito breeding is kept to a minimum. Add anti-mosquito breeding pellets in the water as extra precaution.


If you are growing the plant from cuttings, ensure that the stem ends are in contact with water for its uptake. Avoid adding fish to feed on mosquito larvae in such small containers - it is not only cruel because the water volume in the bottle is too little for the fish, but the rapid fluctuations in water chemistry will also kill fish quickly.

Florist's Gloxinia may be attacked by pests

My two plants are placed in a corner of a lounge that gets partial afternoon sun. I bought the plant with orange-red flowers a few days ago and noticed that the leaves are more green than those of the other older plants beside it, which I had a few months ago. How can I improve the foliage of the older plants

Andrew Nah

For the Florist's Gloxinia (Sinningia speciosa), the appearance of the plant may be due to several reasons.

Is your plant being attacked by mealy bugs? Look under the leaves as well as areas near the crown and surface of the soil. These pests, which appear as cottony masses, suck sap and weaken the plant.

You can spray a very diluted soap solution and use a jet of water to wash them off.

This plant, which has slightly furry leaves, may react adversely to oil-based pesticides such as neem oil and summer oil.

Root mealy bugs, which often lack the cottony texture, tend to congregate at the roots below the soil surface. They can be eradicated only with a chemical pesticide soil drench.

Another pest that may be attacking your plant is thrips. These insects feed on the surface tissue of the plant, leaving a depressed area filled with tiny black dots of waste. They are difficult to manage. A pesticide used to control their population is spinosad.

Lastly, check that you are not over-watering the plant. The media that comes with the plant is often coconut peat-or sphagnum peat moss-based and these materials can retain a lot of water.

Prolonged wetness at the root zone can cause the roots to rot and the plant may appear limp. If this is the case, check for any rot that has occurred on the plant.

Prune the rotten portion and allow the wound to dry. The plant should then be potted in a well-drained media.

Falling hibiscus buds may be due to excessive water

My friend gave me a pot of hibiscus. She said the flowers have multiple layers and look like carnations. I was excited to see buds appearing, but they fell off before blooming. It has happened thrice. How can I prevent more buds from falling off? I have also examined the plant and do not see mites. However, there are ants.

Cheng Shiang

Pests that infest hibiscus, such as thrips and which are known to cause flower buds to be aborted, can be very small and hard to spot.

If pests are not the issue, the cause of falling buds could be due to the growing conditions. Proper watering and protection, such as having a shelter, are crucial during the rainy season. Excessive watering or the lack of it and a saturated root zone can cause buds to fall prematurely.

Heat in the tropics can also be a factor. Some cultivars of large-flowered, double-petalled hibiscus dislike Singapore's high temperature.

Lastly, check the soil's pH level. The leaves have chlorosis, where there are pale yellow areas with green veins. This could be due to a lack of iron and/or magnesium. The pH level needs to be corrected - and this takes time - and a water-soluble fertiliser with chelated minerals may help to resolve the issue.

Brinjal has lacebugs

I have a green brinjal plant in a pot and it started to bear fruit. However, there are white and black spots on the underside of leaves and the condition has spread quickly. I tried to wash the spots off with water and prune the leaves. What are these spots and how can I get rid of them?

Joyce Tang

The pests are likely lacebugs. They feed in groups on the undersides of leaves and leave spots of waste. They can be difficult to control. For small infestations, crush them physically or prune damaged leaves. For larger infestations, repeated applications of summer oil or neem oil may help.

Flowers of papaya tree need pollination

I have been trying to grow a papaya tree to get some fruit, but to no avail. The tree flowers, but the blooms fall before fruiting. How can I get my papaya tree to fruit?

Peggy Theseira

It is important to know the sex of your papaya plant. The lack of fruit could be due to a female plant that is being grown.

Plants that produce only male flowers feature blooms grown on a long pendulous spray. Female flowers are produced singly and are stocky, and they lack the male floral parts on them.

Plants that produce only female flowers will need a male plant nearby for pollination.

Sometimes, you get hermaphrodite plants which produce flowers that contain both male and female parts on the same flower. They are also produced singly and are easily confused with female flowers.

Hermaphrodites can produce fruit on their own.

If there are no pests affecting the papaya plant, a reason the fruit keep dropping could be due to excessive water.

Papaya plants require a sunny and well-drained site to thrive. It may be difficult to transplant your mature papaya plant now. However, do select a more appropriate site in the future to grow a new plant.

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

•Have a gardening query? E-mail it with clear, high-resolution pictures of at least 1MB, if any, and your full name to

A version of this article appeared in the print edition of The Straits Times on December 16, 2017, with the headline 'Root awakening'. Print Edition | Subscribe