Amazon Blue's a good option for a sensory garden

I have this beautiful plant with purple flowers. The leaves look like those of a basil plant, but they emit a strong medicinal fragrance like the eucalyptus'. What is this plant and is it an ornamental one?

Jessie See

This shrub is botanically known as Otacanthus azureus. Its common names include Brazilian Snapdragon and Amazon Blue.

Little has been documented about its traditional uses. Studies about this plant focus on the properties of its aromatic essential oils, which can possibly be used to make perfumes or for medicinal purposes.

It produces attractive blue flowers, a colour that is rare in the tropics. You can use the plant to recreate the look of a temperate English garden by planting it in masses and a natural manner.

It is also a plant to include in a sensory garden as visitors can brush against its leaves and appreciate its scent.

The plant needs moist but well- draining soil and lots of sunlight to grow well. It has to be pruned periodically to rejuvenate and encourage a bushier growth habit.

Tip: Water Plum's changing foliage is attractive

The Water Plum (its botanical name is Wrightia religiosa), better known by its Chinese common name "shui mei", is a shrub that is often trained to grow like a bonsai.

It produces a profusion of extremely fragrant flowers.

Several cultivars are available and a notable one produces new leaves that are all white.

When multiple shoots of a plant produce new growth, the entire plant will have various patches of white. As a result, the plant looks like it is covered in snow, producing an attractive foliage.

As these new leaves mature, they gradually turn green.

This particular cultivar still produces the same fragrant flowers.

You can include it in an outdoor garden, where it should be pruned regularly to keep it low. It should be grown in small groups and used as a foreground feature.

It can also be trained to grow like a small bonsai and planted in a miniature garden to simulate a winter scene, which makes for a good Christmas festive plant display.

Basil needs more light

What type of basil plant is this? The stem used to be a dark, reddish-purple when I got it as a stem cutting. Now it has turned a lighter shade.

Jaimie Lim

The plant is likely to be the Thai Basil (its botanical name is Ocimum basilicum var. thyrsiflora). The change in stem colour could be due to the lack of light.

In an apartment garden, basil plants are best grown in a sunny location where they can get at least four hours of direct sunlight a day. They need to be regrown from stem-cuttings from time to time to ensure the plants remain vigorous and aromatic.

Lacewing a beneficial insect in gardens

I found these things growing on the back of an avocado leaf. What are they?

George Ho

These are the eggs of the Lacewing, a predatory insect. Its scientific name is Chrysoperla rufilabris.

Lacewing larvae will emerge from these eggs and they feed on sucking pests such as aphids and mealy bugs.

Use less pesticide so as not to adversely affect the population of these insects.

In some countries overseas, the eggs of lacewings are sold to gardeners to control sucking pests in enclosed gardens, orchards and greenhouses.

Thyme takes time to flourish

I grow my thyme plant in a planter, but it keeps drying up after a week. Why does this happen?

Chris Wee

In Singapore, you can buy several varieties of thyme.

Originating from the Mediterranean region, thyme needs to be grown in well-draining soil and exposed to about four to six hours of direct sunlight in an apartment.

Thyme plants that are imported are grown in coconut peat, which is too wet for growing the herb here.

However, withholding water from a potted thyme plant is not the right way to keep the root zone dry. Over time, the plant will die due to lack of water.

It is best to take stem-cuttings and root them in coarse sand. Then transfer them to a more well- draining potting mix made up of equal portions of fine, expanded clay pellets and burnt earth. Add a small quantity of compost.

The root zone should be moist and allowed to dry out a little before the next watering. The plants need to be grown under shelter so that they are protected from rain.

It has been observed that thyme plants age very quickly in Singapore - they turn woody and lose vigour.

New cuttings need to be taken to grow new plants. However, growth is slow and it takes a long time before a plant becomes a good size and is useful for cooking.

Hence it is best to buy new potted plants from nurseries.

I have found that out of the various cultivars available, the Creeping Thyme (its botanical name is Thymus serpyllum) grows best in Singapore.

•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 stlife@sph.com.sg