Root Awakening: Pandan plant infested with spider mites

Based on the small speckled spots on the leaves, it appears that this pandan plant has an infestation of spider mites. PHOTO: SINDY ANG

Pandan plant infested with spider mites

Why are the leaves of my potted pandan plant turning brown and pale green? I water it daily and fertilise monthly.

Sindy Ang

Based on the small speckled spots on the leaves, it appears that your pandan plant has an infestation of spider mites. It is a common pest that targets plants grown in high-rise apartments under windy and dry conditions. 

Spider mites can be difficult to manage. You can wash them away with a strong jet of water, and then spray your plant regularly and thoroughly with sulphur soap solution or summer oil. Consistent applications are key to suppressing the pest population.

Wash your pandan leaves thoroughly before using them in cooking.

Do not let jasmine plant dry out completely

This jasmine plant may be shedding leaves because it has dried out from exposure to the elements. PHOTO: JANN HUI

My jasmine plant has been rapidly shedding its leaves over the past week. Most of these leaves are brown, though some are still green. The plant is in a windy and sunny Housing Board corridor and was previously healthy. What is wrong?

Jann Hui

From your description, your jasmine plant may be shedding leaves because it has dried out. Ensure it is watered thoroughly and regularly during hot and dry weather. The windy nature of high-rise environments can cause plants to lose water faster. 

If the plant is still alive and has enough live branches, you may want to construct a wind break using a fine net. You can also move the plant to another location to protect it from drying winds. Ensure your plant gets enough sunlight, as jasmine plants are not shade-tolerant. If your plant is root-bound – a condition in which the roots have filled the container – consider moving it to a bigger pot.

Coleus is an ornamental plant with colourful foliage

The colourful Coleus is an ornamental plant grown for its attractive foliage. PHOTO: KANG HWAY CHOON

These pictures are of my two Coleus varieties. Is the species also called Daun Ati Ati? Also, are they edible or poisonous? I have heard mixed reports.

Kang Hway Choon

The Coleus is also known as the Daun Ati Ati. PHOTO: KANG HWAY CHOON

Both plants are the Coleus, commonly called the Daun Ati Ati (botanical name: Coleus scutellarioides). The Coleus is an ornamental plant grown for its attractive foliage. It is not eaten in this part of the world. When in doubt, it is advisable not to consume the plant.

It should not be confused with the green Indian borage (Coleus amboinicus), a medicinal plant used to treat ailments such as cough and sore throat.

Lemon plant needs nutrients

The hue of this lemon tree's leaves suggests a nutrient deficiency. PHOTO: ANGELINE CHIN

I found this beetle on my lemon tree and subsequently grubs in the soil. The leaves of my tree have also been developing yellow patches and falling off. Is this because of the insects? What can I do?

Angeline Chin

The yellowing leaves of your lemon plant are unlikely to have been caused by the presence of beetles. Adult beetles that feed on foliage will leave behind visibly chewed portions of the leaves. Beetle larvae in the soil usually also do not inflict serious damage to large shrubs. Check the plant’s roots when the opportunity arises.

If the yellow foliage is a problem across the entire plant, it could be due to a lack of nitrogen. Check if the soil is waterlogged, or if your plant is in a pot with soil that is heavy, compacted and drains poorly. Such conditions will prevent the plant from developing a healthy root system and taking up nutrients properly.

Feed your plant regularly. A plant grown in pots should have soil that drains well and contains coarse, gritty components like pumice and expanded clay pellets. Compost can also be added to improve drainage and aeration. If it is planted in the ground, it may need to be carefully transplanted to a more suitable growing site.

Only mature compost should be used to mulch the base of the plant or incorporated into growing media. Immature compost will draw nitrogen from the soil to continue the decomposition process. 

Keep Mexican Star hydrated

The Mexican Star is a herbaceous plant that dries out quickly when grown in a sunny spot. When grown in a pot, its water source may be exhausted by the end of the day.  PHOTO: LIM TIAN SAN

This plant receives partial sunlight and is watered every morning. Why do the leaves wilt in the evening?

Lim Tian San

Your Mexican Star (botanical name: Pentas lanceolata) is a herbaceous plant that dries out quickly when grown in a sunny spot. When grown in a pot, its water source may be exhausted by the end of the day. 

Ensure that you water your plant thoroughly until water seeps out from the drainage holes at the base of the pot. You may want to move your plant to a larger, self-watering pot so that it does not wilt when its root zone dries out. Such pots have a wick that draws water up from a reservoir at the pot’s base to the root zone of the plant.

  • Answers by Dr Wilson Wong, an NParks-certified practising horticulturist, parks manager and ISA-certified arborist. He is the founder of Green Culture Singapore and an adjunct assistant professor (Food Science & Technology) at the National University of Singapore.
  • Have a gardening query? E-mail it with clear, high-resolution pictures of at least 1MB, if any, and your full name to stlife@ sph.com.sg. We reserve the right to edit and reject questions.

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