Q: I live in Defence, Karachi, and have the following plants in my garden: Gul mohar, about 12 feet tall but it has shed all its leaves and a second one planted 10 feet away has very few leaves left. Ficus, three feet high but is not growing any taller. A one foot tall Kungi palm which dried out within a year, a four feet tall mango that is three years old, looks dry and does not sprout new leaves and raat-ki-raani that does nothing at all. I have some others trees too and they remain healthy until they reach about six feet tall. The water table is just three feet below the ground and the soil is saline. How can I counter this problem? Would gypsum help and, if so, how do I apply it?

A: Your trees cannot tolerate either the salinity or the just-below-surface water table. As they grow above ground so too do their roots go down which is why, when they reach a certain size, they begin to die off. Adding gypsum, the amount according to results of necessary soil analysis, does alleviate salinity problems but will obviously do nothing about the water table. You need to plant saline resistant species which will also tolerate water logging —- Casuerina equisetfolia, Terminalis catappa and Proasopis juliflora are suitable — or confine yourself to gardening in pots and raised beds.

Q: This being rose bush buying season I want to take roses from Lahore to Karachi. They are usually available with hard clay soil packed around their roots and held in place with straw. This makes the plants very heavy for transport. If I unwrap the straw and soak the root ball in water for a couple of hours so that I can remove the clay, then pack the roots in moist peat in a plastic bag and plant them as soon as they reach Karachi, will they be okay?

A: This method sounds perfect on the whole but please avoid purchasing peat in any shape or form as over excavation of precious peat wetlands around the planet has serious adverse environmental impacts. Use something like sawdust or coconut husk as packing material instead.

Q: I want to grow sweet basil. What type of soil does it require and what is the best method of cultivation?

A: Basil enjoys humus rich, well drained soil in a warm spot which is sheltered from the wind. Seed is best sown, very thinly, directly where the plants are to grow as basil has long tap roots which are easily broken if seedlings are transplanted. Planting distances vary according to the species of basil being cultivated as some species grow far taller and have a wider spread than others so please follow the instructions given on the seed packet. It can, in the plains, be grown around the year providing that winter crops are grown under cover and that high summer crops are given plenty of water and dappled shade such as provided by fruit orchards.

Q: Many gardeners have a huge problem this season and it is due to the manure we have put on our lawns. Red coloured weeds came in the manure and the more we take them out the more they grow. How can we get rid of them once and for all?

A: Unfortunately you have omitted to provide your location which makes it difficult to identify the ‘weed’ you are having problems with. However, I suspect that either you are allowing it to run to seed before pulling it out, in which case there will be seeds all over the place, or, you are not extracting every single little piece of root which is why it grows back and spreads. Pull it out, digging is probably better, way before it manages to flower and seed and keep on taking it out, tedious as the job is, until it is fully eradicated. This will take time. If the manure had been correctly composted and was fully rotted down the weed seeds would possibly have been neutralised. If you intend repeating the process next season then try to get hold of top quality, fully rotted down, manure.

Q: Is there another kind of tree that looks like Neem and, if so, how to differentiate between them?

A: Neem or ‘Melia Azadiracta’ to give it its botanical name can, when immature, be mixed up with other members of the same family such as Persian lilac or ‘Melia Azadarach’ but is pretty distinct by the time it reaches a bigger size. Neem leaves have a peculiar pungent aroma when crushed; other members of the same family do not.

Q: I have a guava plant and when it outgrew its 14-inch pot I decided to transplant it. When I took it out I saw that it had weird, knobbly roots and now know that this is due to nematodes. Apparently there is no cure. The plant is suffering and its leaves become droopy when it has been watered. Should I throw it out or burn it as I read that nematodes can spread fast.

A: Root nematodes can be controlled and eradicated but your plant sounds like it is too far gone to recover. Dispose of it, along with the soil and pot and start again.

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