Q. I want to grow bonsai in pots in Islamabad. I found an online link to a lady who sells seeds of Pinus parviflora that can be grown as bonsai but the lady says it can grow to over 50 feet. I am confused as to how can I grow it just to a height of five to six feet in a pot. I have found the same trees for sale online in Greece for just four dollars. Could I order from there and get it to grow here?

A. Japanese white pine — Pinus parviflora — is a very popular bonsai subject but this species is not particularly suitable for cultivation in the Islamabad climate. Trees are trained as bonsai through a complicated system of root pruning: a lengthy subject which cannot be fully explained here due to lack of space. I suggest that you research bonsai root pruning and experiment using local, indigenous, species of trees which are naturally soil and climate-compatible. Additionally, establish contact with your local horticultural society so that you can connect with — and learn from — bonsai-growing members.

Q. My guava tree is about two years old and 15 feet tall. This summer it started to form fruit but when the fruit was about an inch in diameter it started to go black and then the tree leaves withered away. Now all the leaves are dead and so is the fruit. Someone said that termites must have attacked its roots so I used pesticide. When I dug the top soil a bit, I found lots of earthworms. The guava tree is planted next to a lemon tree which is doing absolutely fine. Both trees get adequate sunshine.

Your gardening queries answered

A. Athracnose dieback disease is a major problem with guava trees and usually strikes during hot/humid weather or if drainage is not up to the mark. It has nothing to do with termites or with the presence of earthworms — the earthworms are congregating there because of heavy moisture in the soil. The problem, if not fully rectified, could spread to the adjacent lemon tree too. You need to remove every single twig, leaf, dead fruit and so on of the guava tree and as much of its root system as is conceivably possible. Dispose of this infected debris sensibly and far away from your garden. Rectify drainage problems if they exist and then replant with a different species of tree during the winter months.

Q. How can one improve the nature of alkaline soil and alkaline water?

A. Add large amounts of organic compost on a regular basis and, in time, this will have a major benefit on everything you grow. Mix the compost into the soil prior to planting/seed-sowing and then, at least monthly, mulch around plants/in between rows with yet more organic material/compost.

Q. What is a good time to sow French beans in Lahore?

A. September/October are ideal and you can try sowing another lot in March.

Q. This summer my Portulaca plants, both hybrid and desi ones, failed to flower despite full sun and regular watering. They grew well but not a single flowered. Why was this and how can it be avoided in future?

A. These very pretty plants are surprisingly temperamental and often refuse to flower unless treatment leans towards neglect. They need fairly poor soil to bloom as rich soil/feeding encourages leaf growth, not bloom. Drought-tolerant plants by nature, they refuse to flower if given regular water. I suspect that you have cared for them too well.

Q. Is it sufficient to put used plant pots in direct sunlight after scrubbing them out instead of soaking them in disinfectant before reuse?

A. It is okay in extreme summer heat but at other times of the year disinfecting them is recommended.

Q. Can chia seeds be grown in Pakistan?

A. Yes — if you can find them. Growing chia in pots seems to work best.

Q. Please suggest some thick, fast-growing, flowering vines that I can grow to get shade outside my house in Karachi.

A. Tecoma grandiflora (Trumpet Vine), Antigonon leptopus (Sandwich Island Creeper), Allamanda, Beaumontia grandiflora, Bougainvillea, Bignonia, Passiflora (Passion Flower), grape vines, kiwi fruit and Rhyncospermum Jasminoides are just a few suggestions. Check around your local nurseries and see what else they have. If you want to invest in more than one vine, take a walk around the nurseries every month of the year so that you can see exactly what is in flower and when. This will help you decide which vines best suit your interest and your personal vision for round-the-year colour.

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

Published in Dawn, EOS, September 17th, 2017