Ask the Plant Doctor! Growing a healthy lemon tree

Lemon trees require 6-8 hours of direct sunlight daily to thrive. Photo: 123rf

Do you have a question about plants or how to maintain your garden? Send your questions to the Plant Doctor! Email your questions to [e-mail] with "Plant Doctor" in the subject field. Questions may be edited for brevity and clarity.

Q1: I marcotted a branch from a lemon tree that was fruiting and hardly three feet (0.9m) tall. The marcotted branch was then planted in a pot 3ft in diameter and 2.5ft (0.76m) high. It is now eight years old and more than six feet (1.8m) tall. Unfortunately, it is unable to bear any flowers or fruits despite frequent fertilisation with organic and inorganic fertilisers. Please advise. Thank you. – Anthony Chan

The lack of blooms or fruit on lemon trees could be due to root issues. Trees planted in pots, such as a 3ft-wide by 2.5ft-deep container, may become root-bound, causing their roots to tightly wrap around the pot’s interior, making it difficult for the tree to absorb water and nutrients. As the lemon tree grows, the limited soil cannot meet its nutritional needs, and the compacted roots restrict airflow, causing stress to the tree. A simple examination of the roots can confirm this issue. If these signs are present, transferring the tree to a larger pot with fresh soil would be beneficial.

Watering habits also play a significant role. Both under- and over-watering can cause stress in trees, with over-watering often leading to root rot due to poor aeration. Common mistakes to encourage a non-fruiting tree to bloom are supplying excessive amounts of water or watering only after the soil has been left to dry out. Moderation is key to watering. The soil should always feel moist and not too wet or dry.

Sunlight, pruning and fertilisation are other crucial factors. Lemon trees require 6-8 hours of direct sunlight daily to thrive. If your tree is not receiving enough sunlight, it may not flower. Move the pot to a sunny location. Pruning should involve removing only dead or diseased branches, avoiding excessive cutting that could hinder flowering.

Over-fertilisation, particularly with nitrogen-rich fertilisers, can cause the tree to focus on lush green growth at the expense of blooms and fruit. Rapid switching between various fertilisers is another common mistake, as it increases nutrient imbalance or toxicity. Instead, choose a balanced fertiliser designed for citrus trees and consider pausing fertilisation for a few months if you have been experimenting with different fertiliser types.

Q2: I was wondering if you know where to buy Brahmi plants? Thank you. – Cheryl

The Brahmi plant, or Bacopa monnieri, is a perennial, creeping herb native to many regions, including Asia. It is commonly used in traditional Ayurvedic medicine. For-tunately, this plant is inexpensive and can easily be purchased from online merchants.

Assoc Prof Dr Christopher Teh heads the Department of Land Management, Faculty of Agriculture, Universiti Putra Malaysia. His field of specialty is in soil and water conservation. The views expressed are entirely his own.