Gardening: Fashions and fads for gardeners

PHUKET: While horticulture is not an exact science, neither is it an unchanging one. Hence research sometimes arrives at new ways of tackling old problems. Take tree planting, for instance. Conventional wisdom decrees that you dig a round hole a bit bigger than the root ball and fill it with a combination of compost and loam or top soil.

But recent evidence suggests that a compost-rich mixture can have a detrimental effect because it may hinder the root’s attempt to colonize the denser surrounding soil. Moreover, such an area can become a waterlogged sump in the monsoon season, or even a desiccated patch during the dry season. A dressing of soil akin to the surrounding soil will help the plant acclimatize better. And digging a square hole rather than a round one will inhibit the root’s tendency to spiral round the hole, acting as though it were still in a container. Apparently, once roots hit a corner, they tend to flare out into the surrounding soil, significantly aiding their establishment. Of course, it is easier to dig a square hole anyway.

The addition of a small amount of bone meal or granular fertilizer is normally recommended. But it is evidently more beneficial to sprinkle a handful of sugar around the roots. Believe it or not, this boosts the population of mycorrhizal fungi, which have a symbiotic relationship with roots, allowing them to absorb more water and salts such as phosphorus. So sugar can fuel the growth of new roots in newly planted, bare-root trees, while simultaneously protecting them from stress.

If ways of tackling garden practices can change, so too can fashions for plants. One perennial which has become increasingly popular in recent years is the ruellia or three o’clock flower. Apart from its habit of dropping its delicate blooms every afternoon – hence the name – it is a visual delight because of its lavender, trumpet-shaped flowers. Understandably, ruellias have become a fashionable choice for public plantings as well as private borders, not only because of their arresting color, but because they are robust growers and take readily from cuttings. Pink and white varieties exist, but the lavender one is the one to die for.

One way of assessing the pulling power of a plant is by considering how much attention has been given to the creation of hybrids. In Thailand, years ago, half a million baht was paid for a brand new red aglaonema. Already fashionable as a durable houseplant, such riches prompted the development of many exotic cultivars, and along with ever-fashionable adeniums, euphorbias, orchids and plumerias, became the subject of potentially profitable activity by horticulturalists.

To these long-time favorites must now be added the bromeliad. These foliage plants with their distinctive, water-filled rosettes of spathe-shaped leaves, are becoming ‘must-have’ plants, partly because they are basically epiphytic and can adapt to most environments, including soil-less ones, but also because the range of colors is so distinctive. Moreover, they respond to differing conditions of light and temperature. Move your potted aechmea blanchetiana to full sun and the green foliage will turn a brilliant chrome yellow.

If you have gardening or environmental concerns, contact Patrick at drpaccampbell@gmail.com. Many of his creative and academic publications can be found at his website: Green galoshes WordPress.