Root Awakening: Peace Lily needs light; Vietnamese Blue Bell Tree may be dead; infected frangipani

The Peace Lily (left) and Alstonia (right).
The Peace Lily (left) and Alstonia (right).PHOTOS: DANIEL LING DAW CHING, MICHELLE NG

Peace lily needs plenty of light

I bought this Peace Lily about six months ago. Initially, it grew very well, with new leaves appearing regularly, and it even flowered. It recently started wilting and the leaf growth has been stunted. The stem has also started to turn black. I water it about twice a week. It is placed in a sheltered area of my balcony that receives indirect sunlight. What is wrong with it?

Daniel Ling Daw Ching

Your Peace Lily may be the large growing cultivar called Sensation. It will not thrive in deep shade indoors and does better when grown under filtered sunlight for four to six hours daily. Allow it to dry out slightly after watering if you find the growing media to be wet all the time.

A lack of light will weaken a plant as it will be unable to photosynthesise. It also means the growing media will be wet for a longer period after watering, suffocating the root zone. This can lead to rot in the roots and crown. Make sure your plant is not potted too deeply, as soil around the crown can also lead to the same issues.

Plant is alstonia sapling

Can you identify this plant growing in my balcony? I suspect it could be a fruit tree that was planted when some seeds were placed in the pot.

Michelle Ng

This plant is a sapling of Alstonia. There are several Alstonia species that are grown in Singapore's streets, parks and gardens. Their seeds are dispersed by wind and it may be that one such seed landed in your flower pot. Look around the areas near your balcony and you may find the parent tree.

Ginger may not have rooted, chinese spinach has spider mites


The ginger division (left) and spinach plant. PHOTO: CINDY TAN

I planted a sprouted ginger from my kitchen leftovers and it grew. However, its leaves have started to yellow. What should I do and will I still be able to harvest ginger? Also, is my sharp leaf spinach infested with spider mites? How should I treat the infestation?

Cindy Tan

The ginger division may be yellowing due to root issues. Check if it has produced roots in its growing media. They are necessary for the plant to uptake water and nutrients. In an exposed environment without roots, the leaves may dry out and turn yellow.

Another possibility is that the roots are unhealthy. Ginger does not grow well in wet soil where the roots can rot. It fares better in a well-drained, aerated growing mix where it can dry out slightly before the next watering.

The small red dots on your Chinese spinach are spider mites. Neem and summer oils are common, environment-friendly pesticides that can be used to reduce mite populations by suffocating the pests.

Observe the withholding period - the time that must elapse after the application of the pesticide - before harvesting the leaves for consumption.

Do ensure your plants are kept evenly moist throughout their growth period. Plants that are not only dry, but also have wet roots may be more prone to attacks by spider mites. Mist your plants periodically, as that can knock the pests off the plants and raise the ambient humidity if your growing area is windy and dry.

Frangipani infected by rust disease and has mealy bugs


The brown spots on the leaves indicate that the plant is infected by rust. PHOTO: DAVID YC NG

The backs of the leaves of my frangipani plants have a fungus, which is starting to spread. What should I do?

David Y.C. Ng

The numerous small white spots may be mealy bugs, which are sap-sucking insects. You can apply either neem or summer oil to suffocate them. Repeated applications are needed to keep the pest population under control.

The brown spots on the leaves indicate that your plant is infected by rust, which is a common fungal disease. You can remove the infected leaves to prevent its spread. A systemic fungicide, myclobutanil, which is sold at selected nurseries here, can be used as a preventive spray to reduce the incidence and severity of the disease.

Vietnamese blue bell tree may be dead


The Vietnamese Blue Bell Tree is a sun-loving plant and does not fare well in shade indoors. PHOTO: ANG KIM SOON

I bought a serissa bonsai and placed it indoors for a few weeks. The leaves turned brown, so I moved it outdoors to my balcony, but the brown leaves remained. This has been the case for months. How can I get the leaves to turn green again and what is the best way to take care of this plant?

Ang Kim Soon

Your plant appears to be the Vietnamese Blue Bell Tree (Trifidacanthus unifoliolatus). It is a sun-loving plant and does not fare well in shade indoors. Also, the pot is small and may have dried out, which may also have led to the plant's decline.

To check if the plant is still alive, try bending the branches. If they snap easily and are dry inside, that portion of the plant is dead. Do this for the rest of the plant until you find live wood, where the branches are supple and green inside.

If the plant is alive, move it to a larger pot so that the root zone can hold more moisture for a longer period. Make sure the plant gets direct sunlight for at least six hours a day.

  • 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.
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