Q. I am working on wastewater treatment for re-cycling water to use for irrigation purposes. I have planned a constructed wetland with ponds to have bio-remediation methods for improvement of water quality during the re-cycling process. I intend using some of the following plants: water hyacinth, duckweed, pennywort, macrophytes, vetiver grass and a reed bed too. Are these plants — usually found near lakes and natural wetlands — available here and, if so, what are their local names?

A. A wonderful project which, once set up and fully operational, it is hoped that other enterprising growers will, providing they have enough space, also install. Local details of the specific plants you ask about are: water hyacinth, botanical name Eichhornia crassipes and ‘Jal khumbi’ in Urdu, has long been a major pest in Karachi and other areas of Sindh. An introduced invasive species, it clogs up waterways / drainage channels and adjacent areas. Acquiring some roots shouldn’t be any problem but please check the legal precedents (if you reside outside of the areas in which it grows) for introducing a potential nuisance into your locality. I suspect that it is illegal to introduce it into a region which is currently free of it. Please abide by the law relating to invasive species.

Duckweed, botanical name Lemnoideae, Urdu name unknown, is an indigenous aquatic species which is extremely common around Faisalabad where, unfortunately, it blocks drainage ditches and water pumps. Pennywort or Centella asiatica, possibly ‘Gotu kola’ in Urdu, is also indigenous and is a common ingredient of herbal treatments made up by Hakims. Vetiver grass, commonly known as ‘Khas’ or ‘Khas khas’ is no longer as widely grown as it once was but, in recent years, trials have been undertaken to reintroduce / test its durability on arid rangeland. There are countless indigenous species of macrophytes — simply aquatic plants — throughout the country, including various types of reeds which are suitable for the reed bed that is an essential part of your re-cycling design. These plants are not available, with the exception of vetiver grass, in general nurseries and it is against the law to remove any plant from the wild.

Special care needs to be taken when selecting invasive plants

I suggest that you make inquiries about obtaining these plants / seeds from Pakistan Agricultural Research Council, the National Arid Agriculture University, Rawalpindi and the Agricultural University Faisalabad. These departments and universities may also have students who can learn from your proposed design or make inputs of their own. Re-cycling water for irrigation purposes is an issue that must be widely promoted. Good luck!

Q. What is the proper procedure for separating suckers and runners from the mother plant?

A. The process differs from plant species to plant species but, basically, ensure that the suckers / runners have formed strong root systems of their own before, using a sharp knife, cutting them, cleanly, off the parent plant. Next, immediately plant the separated suckers / runners in prepared pots / ground, water in and take special care of them to help them become strongly established.

Q. Please recommend a fast growing tree for Islamabad.

A. Your question raises many more questions: do you want a fruiting, flowering or purely ornamental tree? Do you have room for a large one, a medium one or a small one? Do you want a tree which grows straight up without spreading or would you prefer a tree that provides, in time, lots of shade? Generally speaking, however, small to medium sized trees are preferable in urban areas. Therefore, if you would like fruit, opt for an orange, lemon or grapefruit, an apricot, plum, peach or pomegranate and you won’t go far wrong. If flowering, then Amaltas is pretty, as is Lagerstroemia. If purely ornamental then one of the numerous species of Ficus on offer in all nurseries should be fine.

Q. I started to expand my small garden about a year ago. Initially, the ground didn’t show any signs of salinity but, with the passage of time, salinity began to appear and now, even though I changed the soil in affected areas, there are salty patches all over. Kindly guide me on how to resolve the issue. I reside in Lahore.

A. Salinity is, unfortunately, a rapidly increasing problem in many areas of the country and, as tube wells are drilled deeper in search of illusive water supplies, the problem is going to become far worse. There are ways of treating soil, with gypsum for example, to reduce salinity but, in your situation, I suggest that you construct raised beds, to be filled with brought in sweet earth, plus, homemade organic compost, and grow your plants in these and also in large clay pots / containers. This really is the simplest solution in difficult circumstances.

Q. I have been buying imported goji berries for medicinal reasons but would prefer to use indigenously produced ones. I did mail order from Gilgit but was sent dried grapes not goji berries. Are goji berries grown and dried here and, if so, where can I get them from?

A. Goji berries are indigenous and dried ones can be found in up-market stores. These dried ones come, mainly, from Hunza.

Q. Can figs be grown near Karachi University? If so, then how to go about it?

A. Yes, they can and quite easily. Purchase a pot grown, strong and healthy, fig tree from a nursery: do not buy a ‘bare rooted’ (dug straight out of the soil) tree at this time of the year — bare rooted trees can only be, successfully, moved during the winter months. Dig a planting hole that is twice as deep and twice as wide as the plant pot that the young tree is in, place a handful of rusty iron (not steel) nails in the bottom of the hole as these will supply iron to the tree for years to come, then add a little sweet earth mixed with either old, well-rotted, organic manure or organic compost and water it down.

Next, carefully remove the sapling from its pot, gently spread out its compressed roots and stand it in the hole: the soil level on its main trunk should be exactly the same as it was when in the pot. Then, very carefully, fill in around the roots with more sweet earth mixed with manure / compost, firm it down, water again, add more soil mix if needed, water again and then, the following day, check to see if the soil mix needs topping up once more. Keep the sapling watered, every two or three days, until it is nicely settled in and then water twice a week in hot weather and just once every seven to 10 days in the winter months.

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, Sunday Magazine, April 10th, 2016