Q. Last spring I tried growing cabbages in Karachi. I grew them in pots of 10 inches in depth. They grew well for the first one month but as soon as the temperature started to rise their growth declined. The pot was placed, in the open, on my house roof as it is not feasible for me to grow them under green shade netting. I do have some shady spots in the small garden but preferred to utilise the roof as I intend establishing, if possible, a full rooftop garden there. How can I avoid the same problem with my cabbages next spring?

A. There are two extremely important points here: Firstly, it is next to impossible to establish any form of vegetable garden on a rooftop, in direct sunlight, as conditions resemble those of a microwave oven on at full blast at any time of the year outside of mid-winter. Shade is, therefore, essential. Without this, very few plants — and no member of the Brassica family, including both cabbage and cauliflower, can possibly beat the heat.

Secondly, you haven’t mentioned exactly which variety of cabbage you grew. There are some very different types of cabbages which are season specific, some for cool months and some for the hotter times of the year. It is important to select the one suited to the particular season in which you want to grow them. If you are unable to grow the cabbages, in pots or newspaper lined, wooden fruit/vegetable crates, in a shady location during hot weather then opt for autumn/winter, fast growing ones which will crop when the weather is relatively cool.

Soil, season and species along with proper watering are important ingredients of gardening

Also note that cabbages must be given plenty of space in which to grow and fully develop their nutritious heads. As a point of interest, kale, another Brassica tends to be more heat tolerant than cabbage.

Q. I would like to grow vegetables at my farm near Peshawar and am also a fan of Thai food. Except for lemongrass and, sometimes, sweet basil, I cannot find the fresh ingredients required in making Thai dishes so thought that I should grow them. In this respect, how can I cultivate Kafir lime leaves, galangal, sweet basil and Thai peppers in this part of the country?

A. Sweet basil and Thai peppers will grow perfectly well from an early spring sowing in Peshawar. Kafir limes, botanically called Citrus lystrix will also grow but getting the seed could be a major problem. Galangal, sometimes called ‘Blue ginger’ and a member of the Zingibraceae family native to Hawaii and Indonesia, requires very high humidity as well as year round heat so, even if you can find tubers, they may not do very well.

Q. I grew seven Larkana Guava plants from seed in Karachi. They are now about 30 months old and started developing fruit earlier this year, but the fruit suddenly dried out and died. Next, three of the trees died. I then purchased a plant insecticide for the tree roots but it had no effect and actually caused them to dry up faster. I spread fresh manure around the trees but to no avail. How can I save the remaining three trees?

A. What on earth prompted you to disturb the roots of obviously stressed trees and then, adding insult to injury, spray the poor things with toxic chemicals? Additionally, fresh manure should never be used in the garden as it burns both soil and plants. Always use old, well-rotted, organic manure please — never fresh.

You appear to, sadly, be killing your trees with well-intentioned kindness. Just leave the remaining three well alone, except for regular and copious evening watering, and allow them to grow on as they decide. I suspect that an incorrect, probably deficient, watering regime is the problem here so this must be rectified if your trees are to survive and bear fruit.

Q. I want to grow ‘Sundarkhani’ grape vines in Attock but cannot find the vines in my local nurseries. Please advise on this.

A. This is the wrong time of year to look for grape vines: try again from mid-December to the end of February and you may succeed. If not, then contact some nurseries in the Rawalpindi/Islamabad area and you find what you want there.

Q. Can you please tell me about growing sage and if it is available as herb tea here.

A. Sage, botanically called Salvia officinalis, is a perennial herb and some species are indigenous to Pakistan, more so in upland areas of the country. The actual Salvia officinalis seeds found in the market here, are usually imported and, in the plains and cities, are best grown as early autumn sown annuals to be harvested, for their leaves, in the spring. You can, of course, move potted plants into shade and try to keep them going through the summer heat but, unfortunately, they are unlikely to survive. Sage tea is rarely available in our markets/stores but the dried herb is, and an excellent herb tea can be made from this.

Q. I have a five-year-old pineapple plant. I kept it in a pot for four years and then, one year ago, transplanted it out into the garden. The plant is healthy but has not yet fruited. What should I do to make it fruit?

A. If soil conditions were suitable, the plant would have fruited years ago. It is unlikely to do so now. I recommend starting again, with a new plant, in the iron rich, well drained soil, pineapples need.

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

Published in Dawn, Sunday Magazine, September 28th, 2014