Dragonfruit flowers must be pollinated
This is the second time my dragonfruit plant has produced this flower or fruit. The first time this happened, it dropped after growing. What went wrong?
The picture shows a flower bud that has yet to open. The lack of pollination may be the reason for the lack of fruit production.
Dragonfruit flowers open at night and are reported to be naturally pollinated by bats and moths. In the urban landscape, such natural pollinators may be scarce.
Depending on the cultivar you are growing, you may need to hand-pollinate the flower with pollen from a genetically different plant for reliable fruit set.
Note that the flowers open for only a night and fade when the sun rises.
Coconut palm dies when topped
This coconut tree has almost reached the third storey of my house and is still fruiting.
I am worried it may topple and damage nearby property. Is it safe to chop off the leaves and fruits at the top and still retain the main trunk?
I also love the bird's nest ferns growing on the trunk, but without the leaves, will the trunk eventually rot and die?
Unlike woody trees, the coconut plant is a palm and dies when the crown of the plant is cut.
It can be difficult to harvest fruits from the palm at this height. An assessment of tree failure risk can be done by a certified arborist, a tree-care specialist from a landscaping firm. Move the swing away from the palm to avoid falling fruits and fronds.
If you decide to top off the palm and use the trunk as a support for epiphytic plants, check the integrity of the trunk periodically.
A dead trunk will eventually fall apart. It is best to cut it to a short height, so it will not damage nearby buildings or injure people if it topples.
Sapling is the golden gardenia
I spotted this plant while I was out on my evening walk. It was fruiting. What is it?
Yoke Lan Lee
The sapling is the Golden Gardenia (Gardenia tubifera). It is native to Singapore and can grow into a tree with a height of 8m to 15m under cultivation.
It naturally grows on hills, in lowland forests and along river banks. It produces scented flowers, which are white to pale yellow when they first open and turn intense orange with age.
Aglaonema infested with scale insects
I was gifted this plant about three years ago. It grows well along the corridor without direct sunlight. Lately, white spots have been growing on the leaves. Sometimes, the leaf turns light brown and withers. The spots reappear even after I wipe them off. How can I stop this?
Your plant is infested with scale insects - these are sap-sucking pests common in plants grown indoors. There are no predators in the indoor environment to devour them.
Scale insects are difficult to eradicate as they hide in the leaf axils and other hard-to-reach places.
Wiping a few leaves may solve the problem temporarily, but in the long term, you may want to spray your plant with a soap solution or summer oil, including on the axils and undersides of leaves.
Regular checks and sprays are required to keep the pests away. Test the spray on a small part of the plant to see if there are any adverse reactions, such as burns on the leaves, before spraying the entire plant.
You can lower the concentration of the soap or summer oil to reduce damage to your plant. Also, take the plant to the bathroom periodically and wash it thoroughly with tap water to remove any pesticide residue, dust or pests.
• 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.
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