'Shui mei' plants lack sufficient sunlight

I have two pots of "shui mei". The older of the two plants, which is in a big pot, does not have any flowers. I had pruned its leaves on more than two occasions.

They grew back, but there were no flowers.

The younger plant (pictured), which is in a small pot, had a small cluster of flowers once. I water them twice a day.

They get about three to four hours of sunlight and a fair amount of fertiliser. Why do they not flower?

Wong Wai Cheng

The "shui mei" plant loves the sunlight. The lack of flowers could be a sign that the plants are not receiving sufficient sunlight. Ensure that your plants are exposed to at least six hours of direct sunlight daily.

Also, avoid excessive use of fertilisers that are rich in nitrogen. This causes the plant to produce foliage instead of flowers.

The smaller potted plant has leaves that are chlorotic - green veins against a lighter green background. This is a sign of nutrient deficiency.

Ensure the soil in this pot is not overly compacted. If it is, work some organic matter into the soil and add some fertiliser.

Nutrient deficiency may be cause of yellowing leaves

Some of the leaves of my Cat's Whiskers plants turned yellow (pictured), even though all the pots are exposed to the same amount of sunlight. Why did this happen?

Stephenie Leong

Your plants may be suffering from some form of nutrient deficiency, which could be caused by overly compacted soil whose organic matter has depleted over time.

Compacted soil will lead to stunted root development, which will affect the plant's ability to take in nutrients.

If this is the case, you may want to work organic, mature compost into the soil. Use a fork, but be careful not to damage the root system of the plant.

A layer of compost can be applied as a mulch on the soil surface to help reduce soil compaction in the future. Do not forget to add some fertiliser pellets.

The yellowed leaves could also be a symptom of the plant being pot- bound, where the roots have filled the pot.

If this is the case, you may want to move the plant to a larger pot with new soil.

Also, check if the soil is well-drained. Waterlogged soil prevents healthy root growth and hinders nutrient absorption.

Tip: Small Syngonium podophyllum "Mini Pixie" perfect for miniature gardens

Syngonium podophyllum "Mini Pixie" (pictured) is a shade-tolerant plant that is widely sold in nurseries here.

It is a compact cultivar that rarely grows more than 10cm tall.

Due to its small size, this plant is suitable for growing in a dish or miniature garden.

The plant should be exposed to four to six hours of filtered sunlight daily.

It can also be grown under artificial light, but the light source must be intense enough and placed close to the plant.

The soil used should be moist and well-drained.

Spearmint needs larger pot

I have a spearmint which I have been growing for more than six months. It used to have bigger, broader leaves. However, after those leaves dropped, the new ones are smaller (pictured).

The plant's branches are also thin and wiry. What happened?

Kwan Shuqin

Your spearmint is showing symptoms of being pot-bound, where its roots have filled the pot. Mint plants grow fast and their roots quickly take up the soil volume in the pot.

You may want to move it to a larger pot. While doing so, prune the dead roots, which appear mushy and black. Before repotting the plant, tease out the roots.

Grow creeping thyme in a pot and Pinto Peanut and French Marigold under full sun

Can I grow the creeping thyme as a groundcover? Also, does the Pinto Peanut plant grow better under direct sunlight or partial shade?

I would like to try growing it as a groundcover too. I want to buy French Marigold seeds, but the packs do not mention which variety of marigold seeds are inside.

Does a Marigold plant need full sun to thrive?

Tan Geok Mui

The seeds of the creeping thyme are not commonly sold here. It is often grown together with other herb and spice plants in a pot and sold at local nurseries.

This plant is not an ideal groundcover choice in Singapore - it may not grow well in clayey soil found here. Instead, grow it in a trough or pot, with a well-draining soil mix. Also, it does not flower readily here.

The Pinto Peanut is best grown under direct sunlight. In a shaded area, it grows slowly and has sparse leaves. It will also not flower as profusely. Nurseries sell the plant in bags for direct planting.

The French Marigold, which is botanically known as Tagetes patula, should be exposed to direct sunlight to grow well. The soil should be fertile, moist and well-drained.

Good seed companies should label their seed packets clearly with the botanical name of the seeds they are selling. Marigold plants may be sold in local nurseries prior to the Chinese New Year period.

•Answers by Dr Wilson Wong, a certified practising horticulturist and founder of Green Culture Singapore (www.greenculturesg.com). He is also an NParks-certified park manager.

•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.