Desert Rose lacks sunlight
My plant used to flower very frequently, but has stopped. The leaves also keep turning brown at the tips and eventually wither and drop. New leaves grow, but the cycle continues. I have tried adding earthworm castings, changing the soil and using organic fertiliser, but to no avail. What should I do? Andrew Tan
The plant is called Desert Rose (Adenium). There are many hybrids on the market with a wide range of flower characteristics.
In general, the Desert Rose needs at least six hours of direct sunlight to keep it compact and free-flowering. Plants lacking sunlight will be lanky and poor in flowering.
The reason for leaves turning brown at the tips could be due to overly wet soil.
The plant should be grown in a well-drained soil mix and, in Singapore, coarse Indonesian burnt earth appears to be a popular growing medium for it.
When growing the plant in a shaded area, the watering needs to be controlled so that the soil is not perpetually wet. Overly wet soil can lead to diseases and nutrient deficiencies.
Ensure your plant is grown in a sunny area with good air circulation.
Mugwort a medicinal herb
I attended a horticulture course and the teacher gave me this plant , but I cannot remember its name and whether it can be eaten. Can you advise? Doris Wong
The plant is likely the mugwort. Its botanical name is Artemisia vulgaris. It has aromatic, but bitter leaves.
It is generally considered a medicinal herb. A common way to consume it is to make an omelette with its finely chopped leaves.
The mugwort is used to treat health issues related to the digestive and female reproductive systems. It should not be consumed in large quantities as it is reported to be slightly toxic. Also, it should not be used by pregnant women.
•Answers by Dr Wilson Wong, a certified practising horticulturist and founder of Green Culture Singapore (www.greenculturesg.com). 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 email@example.com
Yam Bean needs a support to climb
I unwittingly left a turnip in a plastic bag for about two months. When I checked it, it was bearing flowers. I decided to grow it in soil and I water it every day. What is likely to happen to the plant? Sereen Ng
The plant is botanically known as Pachyrhizus erosus and is also known by its common name, Yam Bean.
You can grow the plant in a larger pot that is at least 30cm wide. It grows best in a location with direct sunlight for at least six hours daily.
The plant is a climber and requires a support such as a trellis. It produces beautiful blue flowers and bean pod-like fruit.
All parts of the plants, except the swollen taproot, are poisonous and should not be eaten.
Seeds obtained from mature pods can be harvested to grow new plants.
Get advice before using plant as medicine
I found this plant in gardens and along roads. What is its name? Can I use the leaves to treat sore throats or muscle aches? Yhong Tan
The plant is botanically known as Cyanthillium cinereum. Its common name is Little Ironweed. It is a plant that appears as a weed in lawns and gardens.
Despite being a weed, it is also a medicinal plant. However, it is best not to self-medicate. You should seek advice from a herbalist or doctor before using plant materials to treat health issues.
Periwinkle may have fungal wilt disease
My plant has been blooming. But the leaves have started withering. I have been watering it every day and it has full exposure to sunlight. What could be the issue and how can I save this plant? Sean Tang The plant is probably a cultivated hybrid of the Periwinkle (Catharanthus hybrid).
Hybrids of this plant are very prone to fungal wilt disease, which is brought about by very wet soil.
This plant should be protected from rain. Watering needs to be prudent, especially if it is grown in a moisture-retentive media - it should be allowed to dry out a little between each watering.
When plants are infected, fungicide may offer a little reprieveto resolve the issue. All infected plant material needs to be removed and the soil and pot cleaned and sterilised.