Q. What is the ideal soil pH for flowers and vegetables? Is the use of pH paper a suitable measurement of soil pH and how can soil pH be altered from alkaline to acidic and vice versa?

A. A soil pH between six and seven is ideal for most types of vegetable and from 5.5 to 7.5 for most popular flowers. There are exceptions of course, as some vegetables and flowers require specific soil pH outside the ordinary range. Garden lime — preferably organic — is used to reduce soil acidity and sulphur to bring alkaline soils into an acceptable pH range. In both cases, it is necessary to study information on the packets to know how much lime or sulphur should be applied and it varies depending on the existing pH. Litmus paper — presuming this is what is meant by ‘pH paper’ — will only indicate acidity or alkalinity as it does not give the actual pH value. It is better to invest in a soil testing kit or to take soil samples, from three different garden areas, to an agricultural laboratory for testing.

Q. I often see the words ‘regular supply of water’ in this column. Please kindly explain them.

All your gardening queries answered here

A. It means to maintain suitable soil moisture, as required by specific plants, without allowing the soil to dry out.

Q. I live in Karsaz, Karachi and our inside lawn is American grass while the outer green belt has fine Dhaka grass. The problem is that there are so many earthworms beneath the grass that the quality of soil has become very poor. If we step on the grass our feet sink in the soil as earthworms have excavated so much. We sprayed locally available insecticides but this made no difference. What can we do?

A. Wow! Most people here do not have the earthworms needed for basic soil health and, to be honest, I am amazed by what you report here. Having never heard of such an issue before and having now researched it deeply, I must ask if you are 100 percent certain that earthworms are the culprits. It is more common to discover that it is the larvae of other insects, some kinds of beetle for example, that are capable of such damage. Please recheck and get back to me. I am intrigued.

Q. After reading your article about figs I want to acquire plants that produce large figs. Can you advise please?

A. Fig plants should be available in nurseries over the winter months and on into very early spring. I suggest that you ask for the Turkish brown fig variety as, with proper care and adequate water, it flourishes in our climate.

Q. I have planted a tropical almond in Karachi but it has got red coloured insects on it. How can I protect it?

A. If the tree is a young one and not too tall, a thorough spraying with warm soapy water should do the trick as spider mites — the insect pest probably present here — dislikes this intensely. Tropical almond (Terminalia catappa or Jungli badam) is prone to spider mite infestation when young.

Q. I am a beginner in gardening and would like to know how to grow a lemon tree and tomatoes in pots. Also, are there any other vegetables that can be grown in pots as I live in an apartment?

A. Chinese lemons perform very well when grown in extra large clay pots; this variety tends to be more of a bush than an actual tree so is better suited to pot cultivation than the desi varieties which are ‘real’ trees. The hole in the base of the pot must be kept clear so that drainage is good. This can be achieved by strategically placing some overlapping broken pieces of clay pot, at various angles, over the hole before adding a mixture of sweet earth, old, well-rotted, preferably organic, manure and organic compost.

Purchase either a pot-grown or bare-rooted tree (the latter one available in winter) and plant it so that the base of its trunk is level with the soil/manure/compost surface. Water well and then water heavily three times a week, in an evening, so that soil moisture is maintained. Once the bush begins to develop new growth, watering can be reduced to every three or four days in cool weather and every other day when temperatures climb. Never allow the soil mix to completely dry out as this adversely affects the plant health and fruit development. If you live near the sea, the bush will need protection from salt winds.

Tomato seeds should be thinly sown, just under the surface in good, well-draining, soil/compost in seed trays. When seedlings have developed four to six leaves, they can be transplanted, one plant per 10-inch clay pot. Regular evening watering is essential for tomato plants to thrive. Other vegetables easily grown in pots include: aubergines, capsicums, cucumbers, chillies, lettuce, Swiss chard/leaf beet along with essential coriander and mint.

Q. After reading about Swiss chard in this column I want to grow some. Is this easy in Karachi and where can I obtain seeds?

A. Swiss chard/leaf beet grows very well in Karachi, especially during the cooler months of the year. Seed should be easy to find in local gardening shops and Empress Market.

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, October 14th, 2018