Fruiting affected by excessive pruning

My mango tree (left) is 20 years old. It was bearing fruit until I trimmed its branches five years ago. It has stopped flowering since then. Why did this happen and what can I do to make my tree bear fruit again?

Alicia Choo

This could have been caused by how "hard" you pruned your mango tree.

A general practice by fruit producers is to avoid pruning branches back into the woody portions - where the bark is brown in colour. If your tree has been pruned hard, where the branches have been largely cut back, it will take some time for the tree to produce enough crown and foliage to flower and fruit again.

Also, you should avoid constantly pruning your tree as new flowers are produced on new shoots. Avoid feeding your tree with a fertiliser that is rich in nitrogen as it will promote the production of foliage over flowers.

To promote flowering and fruiting, use a fertiliser that has higher phosphorous and potassium content.

Indian holy basil used as herbal tea

What is this plant (left) I bought from a nursery? Does it have medicinal properties? Can the leaves be eaten raw?

Sue Soh

It is the Indian holy basil or Tulasi, which is botanically known as Ocimum sanctum. It is one of the more heat-tolerant basil types to grow in the lowland tropics and is less prone to diseases and pests.

It is more flavourful and aromatic than Italian basil and Thai basil. The Indian holy basil is more commonly used in Ayurvedic medicine, in the fresh form and also as a herbal tea or dried powder. It is used in Thai cuisine to make a dish called Phat Kraphao, a spicy minced pork or chicken dish.

Its seeds can also be soaked in water - they swell up and resemble frogspawn - and are added to desserts and drinks.

Grow herbs in a sunny spot

I just started growing herbs such as basil (left), mint and borage. What is a good way to care for them? Also, is it normal for the borage to shed leaves at the bottom, with leaves remaining only at the uppermost part of the stem? How should I support the lanky stem, which looks rather bare and ugly at its base?

Rick Yap

Most cooking herbs can be grown in a location with four to six hours of direct sunlight daily. For your herbs, you may want to grow them in larger pots.

Lower leaves first turn yellow, dry out then fall off. The loss of such leaves is probably due to short drought periods experienced by the plant. This can be due to the small soil volume for some of the larger plants you have. A small soil volume dries out quickly.

To keep your herbs bushy, pinch off the growing tips now and then to promote the growth of side shoots.

Heat stress may cause leaves to curl

Why do the leaves of my Roselle plants curl up (left)? The plants are grown in pots and left under direct sunlight. They grow tall and often bend when flowering.

Laura Goh

The cupped leaves could be due to heat stress. Heat radiating from the wall can also be detrimental to the health of your plants. You may want to relocate them to a cooler but still sunny spot, and next to greenery instead of a hard wall.

Also, check for small sucking insects on the undersides of the leaves. Such insects can cause leaves to become deformed too.

Finally, you may want to move your plants into larger pots with soil that has some organic matter. The plants have reached a sizeable height and the roots require more space to grow.

Also, a larger soil volume will hold more water for the plants - this can reduce the incidence of drought stress in plants.

Tip: Grow Red Button Ginger for a visual treat

The Red Button Ginger, or Costus woodsonii, is likely the most rewarding and attractive spiral ginger species around.

It is generous with its attractive red lipstick-like inflorescence. The true flowers that emerge on the inflorescence can be added to salads. They taste sweet and sour and add zest to tropical salads.

The plant is fuss-free and does best in either direct sunlight or semi-shade outdoors. It loves to grow in moist, well-draining, fertile soil that is rich in organic matter. It grows easily from stem-cuttings and can also be propagated via division of large clumps.

•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.

•Got a gardening query? E-mail it with clear pictures, if any, and your full name to stlife@sph.com.sg