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The hot weather is burning my plants. What do I do?

July 31, 2016


‘Kalanchoes’ take heat and drought but do enjoy a little shade
‘Kalanchoes’ take heat and drought but do enjoy a little shade

Q. The scorching heat and high temperature in the interior of Sindh is burning up my plants. Temperatures have been 52 to 53oC recently. We heard from some experienced gardeners that spraying water on the plants every morning and again in the evening is the best plant saving method to adopt. What is your opinion?

A. Spraying water on to plants in the morning is asking for major trouble. Hot sun on wet leaves, especially if a wind springs up, results in severe leaf burn which can — although this varies depending on plant species — be fatal. Spraying plants with water at, or just after sunset, is perfectly fine as a cooling method but, keep this in mind please, it can also encourage (depending on general humidity levels) various kinds of fungal disease or infections such as mildew. Giving priority to the selection of indigenous, climatically-suitable-for-your-locality plant species is the best thing to do in future when planning your hot weather garden. Reserve cool climate seasonal plants for growing over the winter period.

Q. The temperature rose to over 50oC in Larkana and seasonal plants, perennials and even small trees have dried out. How can such destruction be prevented in the future?

Different watering tactics have to be used to protect plants in summer

A. It is important to plant locally indigenous species as these should tolerate the increasingly extreme climatic changes the country is now experiencing. It will help, with new plantation / young trees, if shade-netting can be provided. You may also like to try the ‘Matka’ irrigation system since this ensures that the trees and plants have access to water all around the clock.

Q. I have a kitchen garden on the roof of my home in Defence, Karachi, which consists of clay pots and a raised slab bed measuring 6ft x 35ft and 2ft deep. This year, winter and spring crops of normal tomatoes were a complete failure, although cherry tomatoes, grown in winter, were a great success. There seems to be a problem with curly leaf virus for which I sprayed a concoction of garlic, green pepper, balsam vinegar, liquid soap, vegetable oil and essence of peppermint. This dealt with all insect pests but not with the curly leaf virus. Advice please.

Male pumpkin flower
Male pumpkin flower

A. Wow! The insecticide concoction sounds like powerful stuff and it is not surprising that it dealt with all insect pests but, as you correctly noted, curly leaf virus is a different prospect. Tomato curly leaf virus is carried by white flies and it takes up to three weeks after transmission before it appears. Prevention is the only cure. Spray, using your wonderful organic concoction, your tomato plants at the first appearance of even a single white fly. Additionally, keep weeds under control as white flies tend to hide in these. Giving your plants plenty of room to breathe because free circulation of air is also important.

There is, however, a second type of leaf-curl virus in tomatoes: this one is caused by unusually hot or cold weather during the growing season and also by irregular watering practices. There is, obviously, not much you can do about the weather — aside from providing suitable protection such as shade- netting or wind barriers — but do try to stick with a suitable watering regime if, that is, you haven’t done so before. White fly and other pests, along with various viruses, tend to appear on already weak or sick plants of any kind. Maintaining good soil health, with high nutrition, produces healthy plants which, as a rule, can fight off problems all on their own.

Q. Bitter gourd has grown extremely well in large pots on my rooftop in Karachi and bottle gourd has done well too. However, turai, tinda, cucumber, pumpkin and okra have been complete failures. Do they need different soil conditions and different watering? Does growing them together have an adverse effect? Will providing companion plants resolve the issue and, if so, which companion plants do you recommend?

A. The okra is the odd one out here; unlike the others, which are all members of the extensive Cucurbita family of plants, okra thrives in very rich, moist, soil conditions and full sun. Cucurbitas prefer at least partial shade between 11am and 4pm during the height of summer, otherwise they can suffer quite badly. The only problem in growing Cucurbitas together is that they may cross pollinate to produce some unexpected fruit shapes / types. Cucurbitas need plenty of individual root space and lots of nourishment, well drained soil and plenty of water. Providing them with companion plants is not necessary and could reduce air circulation, therefore increasing risks of summer mildews.

Q. In the absence of availability of soil pH meters in the local market, how do you judge whether soil is acidic or alkaline?

A. Simple. Collect a cup full of soil from your garden, divide the soil in two, put these two halves in separate, preferably glass containers (empty jar is perfect). Add half a cup of vinegar to one of the containers, mix it with the soil. If it bubbles or fizzes up, the soil is alkaline. If nothing happens, add half a cup of baking soda and some distilled water (water from an air conditioner drip is perfect), to the other container, mix up and if this mixture bubbles up or fizzes, the soil is acidic. This is a general guide, not pH specific.

Q. The aquaponic way of growing food seems to be the new fad. What is your opinion on this?

A. My personal view is that it is an expensive, overly complicated, fad sprinkled with pitfalls just waiting to happen. n

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, July 31st, 2016