Q. I would like to know if chemical fertilisers such as urea, NPK, DAP etc are necessary for plants? Isn’t it sufficient to apply cow manure monthly? Will it not provide all the nutrients?
A. Chemical fertilisers can deliver quick results and boost yields, but they often degrade soil health over time.Organic fertilisers, like cow manure, release nutrients slowly, which often leads to a more gradual growth pace and sometimes smaller harvests. Many slow-growing ornamental plants do not require any fertilisers. The best fertiliser choice depends on many factors: your plant’s type and life stage, soil quality, container size, and even your local climate and budget.
A plant’s nutrient needs change significantly throughout its life cycle. When it is growing, the focus is more on foliage, before shifting to flowering and fruiting when it enters the maturity and fruiting phases. For a more specific answer, knowing the plant and its growth stage would be ideal. However, I can offer some general principles.
Nutrients in cow manure include nitrogen, phosphorus and potassium, which are essential to plant growth. However, nitrogen is required more during the foliage-development stage and the latter two in flowering and fruiting phases. The difference is significant, depending on what you are growing. For instance, when growing spinach, which is all leaves throughout its life cycle, nitrogen is essential. But if you are growing gourds, that also flowers and fruits, the requirement changes almost every two to three weeks. This changing nutrient ratio is hard to achieve with cow manure alone, as its nutrient profile is relatively fixed.
All your gardening queries answered here…
Q. I am attaching two photographs of fully grown, fruit-bearing papaya trees, which were okay in the morning today but fell to the ground in the afternoon. The trees in our garden in Islamabad were about three years old. Can you explain why this has happened?
A. This is truly heartbreaking, especially with such a heavy, beautiful load of fruit! Several issues can cause a fruit-bearing tree to fall, including unnatural application of pressure on the stem, strong winds and air currents, weak stem, termites attacking the stem, fungal infections or root-rot, overwatering or fruit load on one side, to name a few. Based on the photographs, the most likely cause was the sheer weight of the fruit. The size and quantity of the papayas simply overwhelmed the tree. Staking the stem for support could have prevented this.
Q. I live in Karachi. My five-year-old amaltas tree is almost 15 feet. It receives full-day sunlight and we water it every alternate day. For a while, its leaves have been turning inside and curling. What may be the reasons for that?
A. Leaf curling is typically a sign of stress. Common stressors include improper watering, intense dry heat, nutrient deficiency and pest attacks. The provided photograph suggests the issue is likely related to watering or the recent intense sunlight. An easier assessing method would be to check the surrounding soil from four inches below the surface. If the soil is dry, then the tree is being under-watered and if it is wet and sticking to your hand, then it is being overwatered. Adjust your watering quantity accordingly. Recently, Karachi also experienced scorching, extremely dry sunlight for a few days. This combination of heat and dry conditions can be particularly hard on amaltas leaves.
Q. I have construction bamboo stick pieces, in which I have made holes and I want to grow plants in them. Can it be done?
A. A photograph would help me give a more precise answer, but I can offer some general guidance. In general, the space within a bamboo stick is quite limited. You may use them as planters for small plants, which is ideal for balconies, trellises and confined spaces.
Please send your queries and emails to doctree101@hotmail.com. The writer is a physician and a host for the YouTube channel ‘DocTree Gardening’ promoting organic kitchen gardening
Published in Dawn, EOS, October 26th, 2025