The supply of leafy vegetables has dropped by about 10 per cent in recent weeks, following a spell of rainy weather in Malaysia.
As a result, prices have also risen by at least 10 per cent, according to Mr Tan Chin Hian, vice-chairman of the Singapore Fruits and Vegetables Importers and Exporters Association.
"When there is too much rain, leafy vegetables do not grow very well, and yield is lower," he said. "It is not uncommon for prices to go up and down, especially at the end of the year during the monsoon season."
At Tekka Centre stall Chia's Vegetables Supply, the price of Malaysian-grown kang kong rose by about 50 cents to 70 cents this week to $2.50. Chye sim and kai lan also cost more.
However, consumers are not too deterred by the recent price hike. Housewife Wendy Lim, 55, said: "I love vegetables, so I would still buy them even if there were a price increase of 10 per cent to 20 per cent - as long as it does not go up by 100 per cent."
In general, Malaysian leafy vegetables tend to be more price sensitive compared to other types of vegetables, said Mr Tai Seng Yee, executive director of Zenxin Agri-Organic Food, which gets its produce from 25 organic farms in Malaysia.
This is because they have shorter growth cycles - of around 30 days or less - compared to crops like french beans, which have a turnaround time of about 50 days before harvest.
Mr Tai said: "Demand in Singapore is also high for leafy vegetables, which can drive up the prices when there is less supply."
Zenxin's production of organic leafy vegetables has fallen by about 30 per cent since the end of last month. The company supplies Cold Storage and Giant supermarkets, where 250g of Zenxin chye sim costs $2.50. It has not raised its prices for now.
According to the Agri-Food & Veterinary Authority of Singapore (AVA), 80,544 tonnes of leafy vegetables were imported here last year, around 15 per cent of total vegetable imports.
Last month, 20,000 tonnes of vegetables, both leafy and other types, came from Malaysia, down by 100 tonnes from July.
But supermarkets have not been affected by the bout of wet weather across the Causeway. Both Sheng Siong and FairPrice said there had been no significant changes to their prices or supply of Malaysian vegetables to date.
A FairPrice spokesman said: "We practise source diversification so that our consumers are protected from supply and price shocks." FairPrice gets its leafy vegetables from local farms, Thailand, Indonesia and China.