Flying insects are likely fungus gnats
I have been trying to grow capsicum and onions in small pots, with limited success. Recently, my plants have attracted small flying insects that rest in the pots and on the soil. What are these insects and how can I get rid of them?
Tan Ho Kim
The insects are probably fungus gnats. The adults can be a nuisance; the young appear as small, translucent worms which inhabit soil and may consume the roots of young plants, though the damage is usually minimal. Their presence indicates that your growing medium is wet and rich in organic matter.
Try letting the growing medium dry out slightly before watering again. Improve the soil drainage by adding gritty elements like fine pumice or expanded clay pellets. This will dry the mix out faster and can improve plant growth. Constant wet feet can prevent plants from developing healthy root systems and taking up nutrients.
Your capsicum plant looks leggy, so your plants may not be growing under optimal light conditions. Edible plants in an apartment setting grow best with at least six hours of direct sunlight daily. A lack of sunlight can also reduce a plant's transpiration rate and the evaporation rate of its growing medium.
These growth conditions can discourage insect infestations. You can also try placing BTI anti-mosquito pellets (based on Bacillus thuringiensis subsp. israelensis) to kill existing larvae. Yellow sticky traps can be used to trap flying adults.
Cranberry hibiscus and 'Thai watercress' need more light
I was given these two plants. What are they and how should I care for them?
Carol Tan Hwee Cheng
The plant with the maple-like leaves is known as the Cranberry Hibiscus and its botanical name is Hibiscus acetosella. It should be grown under direct sunlight for at least six hours a day. The paleness of the plant's leaves is a sign that its current spot is too shady. Though sour, its leaves are edible and can be added to salads.
The plant with the more vivid green leaves is a cultivar of Alternanthera. It also appears to be lacking in sunlight. Grown under direct sunlight, its leaves should turn red.
Several species and cultivars of Alternanthera have been cultivated as leafy vegetables. The plant you have may be the Thai Watercress, though it is not a true watercress. Its leaves can be eaten after they are thoroughly cooked.
Self-watering pot may be too small for ginger plant
I am trying to propagate ginger with seramis as the substrate, using synthetic nutrients at EC (electrical conductivity) level 1.2 and keeping the plant out of direct sunlight. What is the correct way to propagate ginger and what EC level is best for both general propagation and seed germination?
The common cooking ginger (Zingiber officinale) can be grown using a soil-less method, but your pot looks too small for it. Note that the ginger plant grows by extending its rhizome - a horizontal underground stem - so any new growth will soon hit the edge of the pot. You should move the plant into a larger container. Also, the ginger rhizome should be kept slightly exposed above the substrate and not too deeply buried, which can lead to rot.
The ginger plant needs at least six hours of filtered sunlight a day and a well-drained, aerated mix. It does not grow well in a moist mix. A standard hydroponic nutrient solution, which is widely available, should suffice. The current EC levels also seem suitable.
Plant is Molokini Portulaca
What is the name of this indoor plant? How should I take care of it?
The plant is botanically known as Portulaca molokiniensis. Its common names include Molokini Portulaca and 'Ihi. It is a succulent that is best grown under direct sunlight for at least six hours a day and needs to be protected from rain with a clear shelter. This plant should be grown in a well-drained mix and allowed to dry out slightly before watering again.
Plants are ZZ plant, Large Flowered Kleinia
What are the names of these plants and do they have nutritional or medicinal value?
The plant with leaflets growing on both sides of a long petiole is commonly known as the ZZ plant and its botanical name is Zamioculcas zamiifolia. It is mainly grown as a foliage houseplant for its attractive leaves and growth form. It is a highly shade-tolerant plant, but fares best in a location which receives at least six hours of filtered sunlight a day.
This plant is not edible. Also, avoid coming into contact with the sap as it contains calcium oxalate crystals that can irritate the skin.
The other plant is commonly known as the Large Flowered Kleinia or by its local Chinese name, Chuan Lian. Its botanical name is Kleinia grandiflora. It is an attractive plant with blueish-green leaves and often grown for medicinal purposes, as it has been reported to possess anti-inflammatory properties. However, do not self-medicate without the guidance of a professional.
The plant appears to need more light as it has thin and stretched stems. It grows best under direct sunlight for at least four hours a day, though it can tolerate some shade.
- 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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