Root Awakening: Avoid eating large quantities of Gynura

Gynura.
Gynura.PHOTO: YOW HO HING, CONSTANCE
Lace Aloe.
Lace Aloe.PHOTO: CHONG NYUN KEE
Dracaena.
Dracaena.PHOTO: GELINA GOH
Mealy bug infestation.
Mealy bug infestation.PHOTO: ANGIE TAN
Allamanda.
Allamanda.PHOTO: YET PEK YEEN

Avoid eating large quantities of Gynura

I was told that this plant is Japanese spinach. Are the leaves edible?

Yow Ho Hing, Constance

The plant is an unidentified species of Gynura. Common species in Singapore which have edible leaves include the Longevity spinach (Gynura procumbens) and Okinawan spinach (Gynura bicolor).

Plants from the genus have been reported to contain naturally occurring compounds called pyrrolizidine alkaloids and these substances may cause damage to the liver if eaten in large quantities. Hence, when in doubt, avoid eating the plant.

Succulent thrives in cooler weather

What is wrong with my plant? I peel away the outer leaves when they turn soft and brown, hoping this will save the plant. The leaves in the centre are still green but not growing. Can the plant be saved?

Chong Nyun Kee

The plant is the Lace Aloe (Aristaloe aristata) or a closely related hybrid. From your picture, its crown is rotting and it can be difficult to save the plant at this stage.

What you can do is remove all rotting tissue and allow what remains to dry before potting it again. The plant can be difficult to grow in the long term in Singapore as it thrives in much cooler conditions.

Dracaena plant lacks water

I bought this plant early this year and the leaves are slowly curling. I water it once a month, using about 1 litre of water each time. It is placed inside the house near the door. The tips of the leaves have been brown since I bought it. Is the plant sick?

Gelina Goh

The plant is a species of Dracaena and is likely the Northern large-leaved dragon tree (Dracaena steudneri). It is a large growing plant that is quite tolerant of shade.

From your description of the leaves curling up, it appears that your plant is lacking water. Ensure the soil stays moist at all times.

It is vital to water the plant thoroughly each time, where excess water flows out from the base of the pot. How fast the soil dries out after each watering depends on factors such as soil type, soil volume and growing conditions. Use your finger to feel for soil moisture below the soil surface and water again when it feels slightly dry.

Manage mealy bugs by spraying oil-based pesticides or soap

I have had this plant for three weeks and recently, white patches appeared on it. These seem to spread to the plant next to it. What are these patches and how can I prevent them from spreading?

Angie Tan

The white cottony mass on your plant likely indicates a mealy-bug infestation. Mealy bugs are pests that suck sap from plants.

Deal with small infestations by washing the pests off using a strong jet of water or dabbing them with some rubbing alcohol.

For larger infestations, organic means involve spraying plants thoroughly with summer oil, neem oil or a dilute solution of castile soap. These pesticides suffocate mealy bugs.

Good coverage and repeated applications are required to keep the pest population under control.

Give your plant the growing conditions - such as sufficient sunlight and water - it needs to ensure it is healthy to reduce the likelihood of infestations. Inspect it regularly so action can be taken early.

Allamanda flowers less after stems are cut

This plant used to bloom with reddish-purple flowers at the end of each branch. As it grew, the branches became very tall. To manage it, I cut them short. Leaves and branches grew from the main stem, but there are no more flowers, despite me adding fertiliser. What should I do? Also, how do I propagate the plant?

Yet Pek Yeen

From your description of the flowers, your plant may be the allamanda cultivar called Cherry Ripe.

When planted outdoors in the ground, it tends to grow into a large, sprawling shrub. It is best to let the plant climb on a tall and large trellis. As flowers appear on new growth, it is not recommended to cut the stems as doing so will give rise to fewer flowers.

To propagate allamanda, it is essential to let the cut ends heal to stop sap flow. This can be done by dabbing the ends in charcoal powder. Then stick the cuttings into a very well-draining mix to allow rooting to occur. The mix should be kept moist at all times in a bright area.

• Answers by Dr Wilson Wong, an NParks-certified practising horticulturist and park manager. 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 June 01, 2019, with the headline 'Root Awakening'. Print Edition | Subscribe