Zahrah Nasir on how best to care for fruits and vegetables

Q: My efforts at gardening were limited to seasonal flowers for 15 years but five years back I began growing citrus in pots — California limes, grapefruit, oranges and kinoo. The limes have been doing well and fruiting for four years. Last December the other trees fruited for the first time. All trees were fed with well-rotted natural fertiliser in December but this spring only one of the grapefruit and one orange tree is fruiting. The limes are fruiting but some of the trees have half-yellow leaves. The leaves of the other trees are okay but no fruit. We are a society of 11 senior citizens and are all having the same problem. What should we do?

A: It is highly possible that there are two distinct problems: 1. You may have overfed the trees in which case they will produce lots of new, healthy growth but forget to fruit. Nothing can be done about this now and they will recover in time but please go easy on feeding them in future.

1. The yellowed leaves indicate mineral/trace element deficiencies which can be remedied by burying a handful of iron, not stainless steel, nails in the soil close to the tree trunks, plus, dissolve a soupspoon full of Epsom salts in a litre of water and feed this same mixture to each tree. The combination of iron nails and Epsom salts will, in time, rectify the matter.

Q: I have a lemon tree in a pot which has been growing well, producing new leaves and flowers. Two months back it produced a lot of flowers but none of them changed into lemons, they all fell off. The same happened a month ago when it again produced flowers but no lemons. I am puzzled.

A: It sounds like your watering regimen may be at fault. Allowing the soil to dry out in between watering and then giving a copious amount of water will cause the blossom to drop without setting fruit. The same applies if you are over-watering all the time. Water little and often and do not allow the soil to completely dry out at any time. Spreading a mulch of organic matter around, but not touching the trunk, will help conserve soil moisture and reduce the need to water.

Q: I am new to gardening and recently began growing things in pots and in the ground in my Karachi home. Recently I found white pests gathering underneath the leaves of some plants and I don’t know how to treat them. Can I use normal insect killer or is this dangerous for the plants? Also, there are signs of fungus under some other leaves. I reduced watering but the leaves have started drying up. What should I do?

A: Do not use insect killer of any kind please. The easiest way is to spray underneath the leaves with warm, soapy water and then wipe off the pests with a soft sponge. Repeat as necessary, each evening, until no signs of infestation remain. The fungus you mention is probably aphids and can be dealt with in the same way. Reducing the water will simply, as you have noticed, kill your plants.

Q: I want to know how to keep my freshly planted Dieffenbachia healthy during summer in Rawalpindi. I have put the pots in my porch so they do not get direct sun. They do get angled sun after 4pm though. Should I water them daily?

A: The location is fine but daily watering should not be needed. Three times a week in the summer should be adequate. Please handle these plants with care as the white sap they contain is poisonous.

Q: We have a few papaya trees in our Karachi garden. They are a seedless, Thai variety and the flesh of the fruit is very dark orange in colour. Recently the shape of the fruit has changed from the outside and the inside is different too: this happened after we gave them normal fertiliser. How can we protect our trees and what kind of fertiliser to use?

A: The type of fertiliser used will not have any effect on the shape or inside of the fruit. If there are other papaya trees growing in the vicinity they could have cross-pollinated with your own and the altered fruit is the result. Unless you resort to the tedious task of hand pollinating the flowers at the perfect time, there isn’t really anything to be done about this — just enjoy whatever fruit you get. Papayas need very little in the way of fertiliser but a decent feed of organic compost every six months may be beneficial.

Q: I grew some tomato plants in pots. I took the seeds from an ordinary tomato. The plants were doing well and I picked some tomatoes but now the leaves are turning yellow and the stems going brown. They are all in the same pot but I had no problem before. How can I save them?

A: Tomato plants have a limited lifespan and may have reached the end of their growing season but, growing them all in one pot was a mistake. One tomato plant per 10-inch pot is recommended. By overcrowding them they will be weak as they have had to compete for light, space, nutrients and water. I suggest that you start off your next crop as soon as possible and follow the one plant per pot routine for healthy, productive plants.

Please send your gardening queries to zahrahnasir@hotmail.com. Remember to include your location. The writer will not respond directly by e-mail. E-mails with attachments will not be opened.