Rooftop gardening is increasingly popular in our urban spaces, where the astronomical cost of a house with a garden is way beyond even the dreams of the vast majority of the population.

Creating a garden on high does, naturally, involve a certain amount of expense, but outlay can be kept to a minimum by being inventive and by recycling all manner of containers that can hold enough soil/compost for some type of plant to grow in.

And the benefits of rooftop gardening are manifold: this out-of-sight garden can be a place of calm and privacy in a world gone mad, a place of beauty and of relaxation, a secret retreat visited by birds, bees and butterflies who are in need of all the help they can get. At the same time, don’t forget that along with helping to keep your home cool via natural insulation from the heat island effect, plants have an all-round beneficial effect on both physical and mental human health, too. All of this and food, too!

The first things you need when starting out are, along with gardening tools of course, a carefully selected array of plant pots and other assorted containers. If the roof is known to be load-bearing, clay and cement pots aren’t a problem but, if you are unsure of how much weight the roof will support, it is best to stick to lighter, usually synthetic, materials or, as long as they are lined with waterproof membrane, purpose-built wooden troughs and wooden-raised beds are ideal — as long as the wood too is treated with something to protect it from water and from the vagaries of the weather. Baskets, lined with waterproof membrane, plastic or with a few layers of old newspaper etc., and wooden vegetable/fruit cartons also make good, lightweight planters.

Don’t forget that any pot/container filled with soil is a surprisingly heavy item and that its weight increases dramatically when this soil/compost is wet.

A rooftop garden can be a place of calm and privacy in a world gone mad as well as a place of beauty and relaxation

Different kinds of plants need differing depths of soil/compost for their roots: many annual flowers and most seasonal vegetables and herbs are fairly shallow-rooted — meaning that an average of six to 10 inches of soil/compost is sufficient to meet their needs — whilst a high percentage of perennial (permanent) plants and shrubs are deeper rooted — requiring 12 to at least 36 inches of soil/compost for their roots to grow in.

Whichever type and size of pot/container, trough or raised up you decide to utilise, don’t forget to ensure that drainage is 100 percent unrestricted, as more plants die from waterlogging than from any pest or disease. Waterproof membrane/plastic, when used to line pots and containers, should have a scattering of smallish holes made in the base before being filled with soil/compost. Drainage is also assisted by raising pots/containers up off the actual floor of the rooftop — standing them on bricks works well as this helps ensure that drainage holes work as intended.

In our climate — and especially if you happen to reside anywhere near the sea in Karachi — a combination of wind and direct sun have the potential to play havoc with whatever you decide to grow. Therefore, protection from both these natural elements is highly recommended. Wind and sun protection can, in time and with knowledge, be grown but, in the initial stages at least, it is the wise gardener who erects firmly — remember how strong the wind can get — secured windbreaks/barriers and shade netting to protect all that grows. Erecting windbreaks and sun shade can make all the difference as to whether your rooftop garden is a success or not.

Top quality soil mixed with top grade, preferably organic, compost/old, well-rotted manure are the ‘gold’ on which the health and associated growth of your rooftop garden depends, so get the very best you can and always have some to spare for those seeds you forgot to sow, in which to start off cuttings given by a friend and so on.

Begin small-scale with just a few pots/containers of plants and see how these react to life on your particular rooftop before expanding the range, as some plants are more suited to rooftop conditions than others.

Soft leaved plants, ferns and seedling/young lettuce being prime examples, are unlikely to survive for long on a fully exposed rooftop when a garden on high is in the initial stages of development, but once hardier plants — primarily varieties with thicker leaves, such as tall growing succulents, evergreen shrubs and so on — have been established as living windbreaks, soft leaved plants can do well in the protected shelter they supply.

Develop the outer edges of the garden first, growing a selection of tough evergreens that reach a height of at least three feet, up to as much as five or even six feet if feasible — this provides wind protection and privacy from other rooftops or overlooking windows in other buildings in the immediate vicinity. Work inwards from there but don’t forget to reserve selected spots for re-potting and other essential garden work, plus a spot in which to lounge around in garden chairs that are heavy enough not to be blown around or blown off the rooftop completely.

Above all though — pun intended — enjoy each and every step of the secret garden you have chosen to create.g — Z.N.

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

Published in Dawn, EOS, March 29th, 2020