Happiness plants may be lacking water
I have three pots of Happiness plants (above). Two started to shed their leaves at the top and new leaves have a crumpled look. A gardener said I could have watered excessively. Is that true?
Teng Shyh Chyang
Your Happiness plant (botanical name: Garcinia subelliptica) may be suffering from a lack of water based on the symptoms described.
It appears that your plant is being grown in a pot. A pot-grown plant will dry out quickly during the hot season. As such, it is important that you ensure you water it regularly and not allow it to dry out. Scratch the soil surface and feel the soil beneath - it should feel moist at all times.
Check if your plant is pot-bound - a situation where the roots have all filled the pot. If this is the case, it is recommended that you move the plant to a larger pot. A larger pot will have more soil to hold water for the plant's uptake in the future.
Finally, the gardener might also be right on the part of over-watering. When a plant is over-watered, its roots will suffocate and die as there is a lack of air in the root zone. When the roots die, the plant is unable to absorb water and will show similar symptoms as those due to a lack of water.
Check the health of the roots - healthy roots will appear white and firm while dead ones will be black, mushy or hollow.
Depending on the extent of root damage and whether a large portion of the root system has been destroyed, there is little chance the plant will recover.
If only a small portion is affected, you can trim off the damaged parts and allow the plant to recuperate over time.
Flower buds of the African violet may have fungal disease
I have had this pot of African violet (left) for three to four weeks. The flowers did not bloom, but shrank and turned brown. This week, I noticed a leaf has turned black. I have moved the plant away from the sun and sprayed water on the soil daily using a spray bottle. How can I grow this plant well?
Your African violet (botanical name: Saintpaulia ionantha) may have a fungal disease affecting its flower buds. This is often caused by the lack of sufficient light, air circulation and perhaps water getting onto the flower buds.
Diseased portions should be pruned and discarded. Avoid getting the flower buds wet if you were to spray the plant or soil again.
Consider "bottom watering" - you place the flower pot in a saucer of water and water is taken up by the growing media by capillary action. This will reduce the likelihood of wetting the foliage and flower buds. Water again when the growing media feels slightly dry.
Finally, give the plant sufficient light to thrive. It grows best in an air-conditioned environment and can be placed under a desk lamp that is switched on for at least 12 hours daily.
If possible, grow it in an airy environment which helps to prevent fungal diseases.
Mint plants need direct sunlight to grow well
I bought a mint plant in December and, after less than a month, it is all but dead. Why is it dying and what is the best environment to grow it in? I grew it in a shady area and it gets some morning sun, but it is shaded generally, as advised by the seller. Can it be rescued?
Law Chee Keong
Mints need good light to grow well. They do best if they can get at least four hours of direct sunlight daily.
If you are growing them under artificial lights, ensure the light intensity is sufficient. Also, such lights often need to be switched on for about 12 hours daily.
Plants that get sufficient light will not be lanky and floppy.
When grown under sunny conditions, mints need to be watered about twice daily. The soil should be kept moist at all times and should never be allowed to dry out.
Mints outgrow their pots quickly and are best grown in large but shallow containers. Regular pruning is needed to encourage a bushy growth and to promote vigour.
The mint commonly sold in local nurseries is a type of spearmint (Mentha spicata), which is characterised by its oval leaves that emit a rather sweet minty scent.
Nectar-rich flowers of Golden Dewdrop may be attracting ants
What plant (left) is this? Its fruit attract ants.
The shrub is botanically known as Duranta erecta and its common name is Golden Dewdrop.
The shrub produces nectar-rich flowers and if your plants are flowering, it could be the nectar in the flowers that is attracting the ants.
Otherwise, check if your plant is infested by sucking pests such as scales, aphids or whiteflies. These pests are known to produce honeydew, which is a sugar-laden excrement, that can also attract ants.
They should be managed by spraying the plant with summer oil or neem oil on a regular basis until the population is kept under control.
This plant needs to be grown under direct sunlight for at least six hours daily. It appears that your plant is situated below the parapet, which is a sunless spot. Try to move it to a spot where it can get the right sunlight intensity it requires to thrive.
• 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