Homes Homes Outdoor

Gardening in Hong Kong: What to consider when choosing which tree to plant

gardening in Hong Kong, what to consider when choosing which tree to plant, Hong Kong, gardening

I’m still wondering what to put in place of a much-loved Peepul tree (Ficus religiosa) that went down during last year’s Typhoon Vicente’s approach. It was visible out of the corner of my eye as I worked at my computer and I miss it more than I would have imagined. It was a beautiful tree in itself, but it also had practical value as a filter between our house and the buildings that have sprouted in the background over the past 30 years since we moved here. We are now far more aware of neighbourhood noise and we have lost the screen that tempered the fiercest sun in late summer.

Hong Kong’s sub-tropical climate means no shortage of suitable replacement trees. Bananas should put up a quick screen in no time, but I would like to find something taller with a longer life expectancy. Erythrina grows fast and has cheerful red flowers full of nectar that the sunbirds adore. But it usually grows more or less straight up, so it won’t create the canopy that I want.

Hong Kong’s national flower, the Bauhinea blakeana is an appealing idea. It spreads into a majestic shape and looks good even without the fragrant flowers that earn the popular name “Hong Kong orchid tree”. It’s a fast grower, too, but the wood is brittle which makes it susceptible to storm damage. Spathodea campanulata (African tulip trees) are stunning. But they are best appreciated from above as the flowers open upwards on the topmost growth. My neighbours would be the main beneficiaries of such a choice.

Nature abhors a vacuum and if I don’t take the initiative soon, Macaranga and Popinac seedlings will sprout and fill the space. Both are invasive non-native trees and I really find it hard to like them.

Ceiba, Plumeiria (Frangipani), Mulberry, Syzgium (Rose or Water Apple) all have their appeal. Perhaps my favourite tree is Terminalia mantaly. A native of Madagascar, it will eventually reach 10 to 20 metres in height, and it’s a neat and dainty grower, with layers of horizontal branches; also, the leaves are small (offering negligible wind resistance) and coloured cream and green with a decided pink tinge when they first emerge. The name derives from its charming growth habit of sprouting leaves from the ends of the shoots. Maybe I should just put in pieces from the Moringa oleifera (Drumstick or Horseradish tree) that has flourished elsewhere for decades and provided leaves and fruits for thousands of curries.

Choosing a tree

If you plan a long-term relationship with your garden, you should select your tree with care. Hong Kong has many Auracaria (Norfolk Island Pines) that were probably cute as “Christmas trees”, but 20 years later they tower skywards at an ever-increasing speed. In their native habitat they are famous for being able to cling to the most unpromising cliff and withstand gale-force winds year round. So once you put them in, you have them for life! They can grow to a height of 40 metres or more, so be sure that this is what you want. The same goes for rubber trees which are increasingly aggressive space-hoggers as they age.

The right tree in the right place adds balance and focus to a garden. In the wrong place, however, it can be a visual disaster and eventually something of a nightmare if it gets too big for its surroundings. If you plan to live with the tree for a long time, take your time and choose carefully. Check the average height and diameter that the tree will reach when mature and consider whether that is likely to be too dominant in the space that you have available. Estimate the shade that it will cast and imagine whether that will be too much of a good thing. When you see a tree that you really like, try to find the scientific and Chinese name. Photograph it so that you can show it to a nursery like Wing Ho Yuen or Sun Fung in the hopes that they can source a specimen for you.

Planting a tree

In the pursuit of instant landscaping, Hong Kong and China have perfected the art of transplanting mature trees, but this is an expensive, highly specialised business that must be done properly if the tree is to survive. Quite apart from transport logistics, you probably require a crane to manoeuvre the tree into position, and carry out skilful underpinning to hold it securely in place. The rootball must be secured to wooden “deadmen” at the bottom of the planting pit, eliminating the need for ugly and hazardous over-ground tethers and stakes that used to be the norm.

If you can be patient, it’s best to start with a relatively small and manageable tree that can be allowed to settle in at its own pace. Be sure to match the level of the “collar” on the trunk when the tree was in its nursery container. If the collar is below or above ground level, your tree will probably rot. Consider the drip-line of the tree as it matures. Ideally the roots should have as much expansion space underground as the branches have in the air when they spread out. And don’t even think of laying concrete, tiles, or bricks close to the trunk: they are the arborist’s equivalent of foot binding and your tree will not thrive long-term.

If you expect to move home within a few years and you intend to take the tree with you, best leave it in a pot or tub. Digging even a small tree out of the ground is not something to undertake lightly. If you place trees on your terrace or rooftop, stand the containers on bricks to enable air to circulate underneath and also avoid cooking the roots on hot summer days when the ambient temperature on an un-shaded roof or terrace can rise to over 40 degrees Celsius.

Jane Ram is a long-time Hong Kong resident, the immediate past chair and long-time committee member of the Hong Kong Gardening Society and a well-known broadcaster and writer on garden-oriented topics.