Ask the Plant Doctor! Growing basil with success

Basil is a sun-loving herb and thrives with approximately 6-8 hours of direct sunlight daily. Photo: Lavi Perchik/Unsplash

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.

Q I have tried growing basil in a pot on my kitchen counter which receives moderate sunlight coming in from a nearby window about 3ft (0.9m) away, but I have been unsuccessful. I tried placing it next to the window as well but that did not work either. Please advise. — Elle

Basil, a sun-loving herb, flourishes best with approximately 6-8 hours of direct sunlight daily. In the intense tropical sun of Malaysia, however, providing afternoon shade can help prevent overheating and leaf scorch. For indoor growth, moderate light from a window three feet away might be insufficient. It is better to place the pot in an outdoor area, such as a patio, balcony or garden bed that receives ample sunlight.

For soil, opt for a mix specifically designed for herbs or vegetables rather than conventional potting soil. This should be a loose, well-draining and nutrient-rich medium. Incorporating compost can enhance its quality. Ensure that the pot has drainage holes, and water the basil only when the top inch of soil is dry, as basil does not tolerate soggy soil and wet leaves.

A balanced organic fertiliser with roughly equal NPK ratios (such as 4-4-4 or 5-5-5) can provide even nutrition. When initially planting basil, enrich the potting mix with slow-release organic fertiliser pellets at a rate of about 2-3 grammes per litre of soil. This addition will provide sustained nourishment to the plant over a period of 6-8 weeks.

Additionally, for an organic boost, blend in roughly 20-30% compost with the potting mix. This not only acts as a natural fertiliser, but also improves soil structure and health. Every 2-3 weeks post-planting, apply a diluted liquid organic fertiliser, such as fish emulsion or seaweed extract.

If opting for only chemical or inorganic fertilisers, apply urea fertiliser at a rate of 6g per square metre ground area before planting. Then, after planting, apply a balanced 15-15-15 fertiliser at a rate of 15g per square metre ground area once every 3-4 weeks.

Monitor the basil leaves for signs of over-fertilisation, such as very dark green, limp and excessively large leaves, and reduce fertiliser application accordingly.

Regularly trim the growing tips to encourage bushier and thicker growth and pinch off flowering stems. In tropical environments, pests such as aphids and caterpillars are common, so be vigilant and use gentle insecticidal soap or sticky insect tapes or traps for treatment if necessary.

Basil can be cultivated year-round in Malaysia. With the right location, soil, watering practices and care, you can enjoy a lush and productive basil plant.