Q. I have three orange trees in my Lahore garden. Every spring, the trees produce new leaves and flowers but only a few flowers convert to fruit. Please tell me how to encourage the flowers to turn into fruit. I spray the trees with a combination of neem oil and liquid soap twice a month and also use fertiliser granules at the tree roots.

A. Spraying your orange twice a month is totally unnecessary unless, of course, there is a visible pest problem. In that case, the trees should be sprayed with neem oil and liquid soap mixture every alternative day until pests are eradicated. But it is highly probable that this unnecessary spraying is interfering with the fruit set. As you will be aware, fruit blossom must be pollinated for fruit to set, but the spray does not differentiate between pests and pollinators. Plus, it leaves a residue on the tree which is offensive to most pollinators who will, once they smell it, move on to something else. Pollinators must be encouraged if you are to get a good crop of fruit. You didn’t mention how often you fertilise the trees. A high potassium fertiliser — preferably organic seaweed based one — given once every three months around the year, is perfect.

Q. I have a six-or seven-year-old lychee tree but it does not fruit. What is the problem and how can it be resolved?

A. Lychee trees grown from cuttings or grafted ones, generally take three to five years to fruit, whilst seed-grown ones can take as long as 15 years, so perhaps your tree is too young. Some varieties of lychee also need cross-pollinating by another lychee tree before they will bear fruit. In addition, much depends on the local climate but you have omitted to provide location details so I cannot be more specific.

Q. I have a spacious rooftop at my home in Karachi and want to grow fruit trees on it, in big terracotta pots. Are dwarf varieties of olives, peaches, apples, persimmons, banana and pomegranate suitable for the Karachi climate? And if so, are they available here? 

A. Much depends on how close to the sea you are and how exposed to wind the rooftop is. If you are well away from the sea and can securely erect some form of wind protection — along with shade netting against the full furnace heat of summer sun — then dwarf fruit trees you can try planting include: olive, fig, lemon, kumquat, finger lime, sharifa, chikoo, papaya, guava and pomegranate. You could also train some grape vines, passion fruit vines, kiwi fruit vines and star fruit vines on and along suitably strong supports. For availability of these — and possibly a few more — you will have to make regular checks of nurseries in your area and also discuss your requirements with nursery owners.

All your gardening queries answered here

Q. Can I grow cardamom in Peshawar and, if so, how to do it?

A. Cardamom is a tropical plant and therefore not suitable for cultivation in Peshawar.

Q. Can cooked vegetables be added to the compost bin? They have oil and spices in them so I am not sure.

A. Plain cooked vegetables can go on to the compost heap and spices are not an issue either. But oil, in any shape or form, should not be added at all.

Q. I need advice on growing healthy pea plants, such as how much water they should get, in Lahore.

A. Peas are best grown over the cooler months in Lahore, as the plants tend to burn up in summer heat. Soil should be rich in compost and well-rotted manure, as peas are hungry plants which need lots of feeding to produce good crops. The soil in which they are growing should be kept lightly moist at all times and never be allowed to completely dry out. Therefore, unless it rains, watering at least every other day is essential in relatively cool weather, and daily once temperatures begin to rise.

Q. I have 20 dahlia plants in pots. But only one of them is flowering. I applied triple phosphate to make them flower but that didn’t work. Please tell me what to do.

A. Please do not overfeed your dahlias if you want them to bloom. All they need is a decent amount of, preferably organic, old, well-rotted manure/home-made compost mixed into the potting soil when you plant them and then nothing else, aside from water as necessary. When dahlia plants are overfed, they produce lots of wonderful green growth but fail to flower as they should.

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, May 10th, 2020