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Heat Beating

April 03, 2016


Natural cooling system
Natural cooling system

With last summer’s unprecedented heat wave — and Karachi’s ‘Heat Island Effect’ that multiplied it — low cost methods of keeping cool continue to top the ‘to do’ agenda for humans, plants and wildlife alike.

Wise gardeners, along with environmentalists throughout the country, have — and continue to — prioritise tree planting campaigns in every size and form possible in the on-going battle to alleviate the long-term effect of climate change. Unbounded enthusiasm has though, very unfortunately, led some of these otherwise laudable tree planters astray; serious selection mistakes have been made by some government departments as well as by private individuals. In Lahore, for instance, local authorities have, for completely inexplicable reasons, apparently chosen to concentrate on planting costly, non-native tree and shrub species which, if they are to stand the slightest chance of survival, require unrealistic — given persistent and serious shortages — volumes of water on a regular basis. These ‘exotic’ species are also detrimental to local biodiversity as their pollens, fruits / seeds are unknown and unrecognised by indigenous wildlife, such as birds, bees and butterflies, which is already on the verge of urban extinction. Lahore now has just 3pc green areas — against the recognised world standard of 25pc – 30pc — and planting high maintenance, unlikely to survive for long, imported trees and shrubs, is not going to resolve this extremely serious state of affairs.

In urban areas where mature trees and shrubs — alongside Lahore canal being a prime example — have been cut, it is eminently far more sensible to replace them with indigenous — therefore climatically suitable — varieties. In any way, there is no getting away from the fact that mature trees, particularly spreading, shade providing ones, do far more to ‘instantly’ keep the city cool than the tiny saplings being planted to replace them.

Planting more shade giving trees is a good way to reduce the chances of heat wave in summer

Trees, even indigenous species, do — on the whole — take time to grow and provide any potential benefits and, let’s face it, far from all urban dwellers have space to plant even a single tree at their home. On average, if a tree is 10 metres tall, its root system is liable to spread 10m - 15m all around the tree, if 15m tall then 15m - 22.5m around and so on. Tree roots can play havoc with underground water / sewage systems, electricity cables, etc. They can also seriously undermine building and boundary walls and road surfaces.

Therefore, if a tree / trees, is / are out of the question for you, then other, preferably rapid, ‘shade creators’ may be an ideal way in which to cut summer heat from both inside and outside your home. Here are some shady suggestions:

  • Grow perennial climbers / creepers over strong supportive frameworks — these can be improvised out of recycled lengths of wood / branches, bamboo, re-purposed plastic / aluminium / iron pipes / guttering or any other strong material you have lying around or which you can acquire at little, or no cost. Let your imagination run riot to create archways, gazebos, walkways, shady seating nooks or — if you have a small courtyard — grace it with a living ‘roof’ to turn it into an outdoor space with maximum ‘cool’ factor. Suitable climbers / creepers for creating such shade, include: Bougainvillea, Tecoma grandiflora, Passiflora, Allamanda, Banisteria laurifolia, Beaumontia grandiflora, Bignonia, Jasmine, Thunbergia grandiflora or, for a classic Mediterranean impression, grape vines are the answer.
Flower of the month — Calendula
Flower of the month — Calendula
  • Cover the outside wall of your house or apartment with a fixed trellis made out of firmly fixed wood, bamboo or exceptionally strong wire and grow climbers / creepers over this. You will be surprised at the cooling effect it has on the interior of the rooms immediately behind it. Ideal creepers / climbers for this purpose include all of those mentioned above, plus, up to a ‘reachable height’ and depending on the season, climbing beans, peas, cucumbers, tori, lauki, climbing squash / pumpkins or karela.

  • Creating gardens on flat rooftops — it is wise to check, if possible, with the original architect, about the load bearing potential of the roof first — helps to insulate the house / top floor apartment, against summer heat and winter cold.

  • If none of the aforementioned are suitable, then invest in the strongest green shade netting you can afford and, using whatever support you can put together, shade your terrace, veranda, courtyard or garden area with this. If buying netting is out of your budget, second hand net curtains, dyed green, make a good substitute. You can also — depending on your locality and availability of raw material — weave simple, traditional, very attractive, natural shade out of palm fronds / bamboo.

  • Traditional ‘chiks’ are, of course, another option but, these days, the cost tends to be prohibitive.

It is all go — as per usual — on the seed sowing front this month and vegetables to go in now include the following: sweet potatoes — both tubers and cuttings, ladies finger, tomatoes, cucumber, aubergines, capsicum, chillies, leaf beet / Swiss chard, lettuce, cauliflower, loose leaf cabbage and, as long as you get them in before April 14, some late pumpkins, zucchini, courgettes, marrows, tindas and loki. Grow all of the leafy greens in partial shade from now on through until the autumn as they tend to wilt in hot sun. Growing them in partial shade also helps reduce their water consumption.

Suggested herbs to go in this month: lots of different varieties of basil, borage, coriander, chives, garlic chives, summer savoury, calendula, nasturtium and ginger.

Fruit: melons, water melons and pineapples.

Flowers: lots and lots of spectacular sunflowers, amaranthus, celosia, rudbekia, coreopsis, cosmos, sunflowers, gompherena, portulaca, petunias, marigolds, tithonia, nicotiana, gaillardia, matricaria, tagetes and zinnias.

Flower of the month

Calendula officinalis — family Compositae — common name ‘Pot Marigold’ is a hardy annual which can, as its botanical Latin name implies, be sown all around the year and which can be had in flower on the first day of every single month. It is grown as an ornamental garden flower and as a very useful culinary, medicinal and cosmetic herb.

It’s one of the easiest flowers to grow as it is not particular about soil type, and thrives in full sun or light shade. Sow seed just beneath the soil surface and water sparingly.

Flowers can be single or double and are in shades of yellow, orange, cream, delicate pinkish or reddish. Makes a good cut flower. Height 15cm to 60cm.

Please continue sending your gardening queries to Remember to include your location. The writer does not respond directly by email. Emails with attachments will not be opened.

Published in Dawn, Sunday Magazine, April 3rd, 2016