Peppermint and spearmint leaves look, taste and smell different

I have been growing this cutting in the plastic bag it came in, as I intend to let it stabilise before potting. My friend told me this is peppermint. Is it peppermint or another plant?

Chia Chiew Theng

Your cutting looks to be a cultivar of the spearmint (Mentha spicata). The scent and flavour of spearmint is generally milder and sweeter than peppermint (Mentha x piperita), which has a different leaf shape, scent and flavour.

Numerous cultivars of both mints exist and they vary in terms of their scent and flavour. They are edible and are widely used in cooking, as well as garnishing dishes or as a sauce.

Fruit produced by shrub-like cotton plant

I found these packed with some Christmas gifts. I saw what I believed to be cotton trees in Changi Road when I was young, but was told that cotton plants were actually shrubs. Are there cotton plants in Singapore? If so, where can I find them?

Tan Pin Ho

The fruit in the picture are those of a cotton plant which belongs to the genus Gossypium. This plant grows as a shrub and is planted for educational purposes in some school and community gardens. The trees you mentioned are likely the Silk Cotton Tree, also known as the Kapok Tree (Ceiba pentandra).

Chilli have edible fruit

What plant is this? Is it edible and does it have medicinal properties?

Sabrina Lim

The plant is a cultivar of ornamental chilli. Numerous chilli cultivars exist and some produce attractive fruit, which make them suitable as ornamental plants. These fruit often turn red when ripe and some are edible, although they vary in terms of their spiciness.

If you bought this plant from a nursery, you can harvest the fruit for seeds, which can be grown into new plants. However, if you do not know the details of this plant’s production – such as the type and frequency of pesticide application – it may be best not to eat the fruit for food safety reasons. 

Fern leaves may have been eaten by pests

My fern’s leaves are healthy and clean, but they seem to have been eaten in parts. There is no evidence of pests that I can see.

Charlie Goh

The fronds of this bird’s-nest fern seem to have been eaten by snails or slugs. These garden molluscs, which are active at the ground level, eat the tender tissue of new, developing fronds.

Snails and slugs inhabit dark, moist places in the garden and are most active during the rainy season, especially at night. They hide during the day, making them difficult to find. Look out for them at night after rain, where they will be easier to catch and remove. You can also lay out snail pellets, which are available for sale in local nurseries, as bait to kill the pests. Ensure these pellets are not ingested by children or pets.

Daun Limau Purut infested

I have three Daun Limau Perut plants, two in the ground and one in a pot.

The first picture is of the mother plant, which is about six years old and planted in the ground. It was very tall and had large green leaves until I pruned it about two years ago. It never recovered and developed spots.

The second picture is of two plants marcotted from the mother plant. The one in the pot has developed dense spots on the leaves. The larger plant in the ground – also marcotted from the mother plant – also developed different spots.

What could be ailing these plants and how do I help them recover?

Gan Boey Keow

The numerous white spots on the leaves of the mother plant are likely caused by mites. Spraying your plants with summer oil on a regular basis will kill these pests and may help to prevent new spots from appearing. Thorough coverage of the plant is necessary to provide adequate control. Affected leaves will not recover.

Your marcotted plants’ leaves have irregular golden spots. These may have been caused by a rasping pest – possibly the long brown spot visible in the bottom right of the photo – that scrapes surface tissue off the upper part of the leaves. Observe its feeding pattern to be sure.

Summer oil may work on such a pest but, for more effective control, you may want to use a pesticide like pyrethrin, which is derived from the flowers of a chrysanthemum relative and is available in local nurseries.

When spraying garden chemicals, wear appropriate personal protection equipment and follow the instructions on the product label. Ensure the chemicals are suitable for use on edible plants and observe the withholding period – that is, the duration that needs to elapse before sprayed plant parts can be harvested for consumption.

• Answers by Dr Wilson Wong, an NParks-certified practising horticulturist and parks 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.