Frangipani has rust disease; fiddle-leaf fig needs bigger pot

My ficus’ leaves have become yellow and burnt over the past six months. It is on a south-facing patio and gets full sun from the west in the evening. I try to water it every other day. How can I improve its condition?

Also, my frangipani’s leaves have a rusty appearance. The plant flowers well, but the leaves seem to shed every few months. What is wrong?

Alex Fong

The Fiddle-Leaf Fig may be sunburnt if it is exposed to direct sunlight in the open, especially as such plants may previously have been grown in retail nurseries under shade. Such plants need to be acclimatised slowly to adapt to higher light levels. If your plant has been out there for some time, let it be. Older, damaged leaves will shed naturally over time.

Also, it appears that your plant is still in its original pot, which may be too small as the plant grows. Try moving it to a bigger pot which can hold more soil and water. This will enable the plant to thrive in drier, sunnier conditions.

As for your Frangipani, its leaves seem to have been infected with rust, a common fungal disease that can be difficult to control. The use of fungicides such as chlorothalonil and copper soap may help. Spray on a day with good weather so that the fungicides are not washed away by rain. Remove infected leaves to prevent the spread of the disease.

Indian Borage needs to be moved to a larger pot and pruned

What plant is this and how do I care for it? The stems are growing outwards. Can they be cut for repotting?

Sindy Ang

Your Indian Borage plant may be potbound, meaning that its roots have filled the pot. If this is the case, move the plant into a larger pot for it to grow. A potbound plant dries out easily as the limited soil volume can hold only so much water.

Water your plant regularly, ensuring the growing medium is moist. If your plant is potbound, underwatered or both, it will suffer from moisture stress when the roots dry out. This can cause the leaves to fall, as you are seeing here.

Prune the leggy-looking branches back to a green node along the stem to promote bushy growth. The tip cuttings can be rooted in different growing media to produce new plants.

Chinese violet produces edible leaves

My neighbour gave me this plant and claimed it is edible. What is it?

Vivienne Lew

Your shrub is likely the Chinese violet and its botanical name is Asystasia gangetica. In Singapore, it is often called “Taiwan Kau Kee” which translates to “Taiwanese Wolfberry”, though it is not related to the wolfberry. It is a common shrub that is planted in urban landscapes and its leaves are food for caterpillars.

This plant’s young leaves can be eaten but need to be cooked thoroughly before consumption; for instance, by boiling them to make soup.

Alstonia trees produce scented flowers

What is the name of this tree? Its flowers have a pleasant, slightly soapy fragrance.

He Weiqing

The tree in the picture is likely an Alstonia species. Commonly called Pulai, there are several species of this tree in our local parks and gardens, and they produce scented flowers. A closer examination of the tree is needed to discern the exact species.

Nerve plant needs to be replaced

My son’s terrarium plant has withered. There was mould on the leaves, which I wiped off. How can I revive it?

Kaye Ng

Your nerve plant (Fittonia) is dead. You may want to visit a nursery for a replacement.

In a sealed terrarium, the growing medium must be kept moist at all times in order to prevent plants from drying out. To prevent mould from forming, the terrarium has to be opened occasionally to let excess moisture escape. Also, do not overwater the set-up, as waterlogged plants will rot and die.

Place the set-up under grow lights that are bright enough to support plant growth. Plants should not appear stretched under optimal light conditions.

• 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.