Hands up who has a browning, wilting herb plant on the balcony – one that, for reasons unknown, has given up? Humidity, over-watering, under-watering, poor soil and unidentified critters: plants die for a whole range of reasons. Since we know we’re not the only enthusiastic but perplexed would-be gardeners in Singapore, we though we’d ask the experts at National Parks for tips on cultivating a bumper herb crop.
Parsley, rosemary, thyme, basil, mint, oregano and bay leaf are culinary herbs commonly used to spice up Western dishes. Many originate from around the Mediterranean and can be challenging to grow in tropical climates. In their native habitats, most of these herbs are found in sunny areas where the soil is dry, well drained, alkaline and lean in nutrients.
To grow them successfully in Singapore it is necessary to replicate these conditions. (The exceptions are basil and mint, which like to be kept moist and do not tolerate drying out.) Herbs can be successfully grown in apartment locations that receive at least four hours of direct sunlight. There are advantages to growing herbs in high-rise settings, too: they are given some shade from the intense light of the midday sun and protection from excessive water from heavy downpours.
Here are some other tips for growing herbs in tropical climates.
Grow herbs in individual pots, rotate them weekly and space them out to allow air circulation between plants and to maximise exposure to sunlight. This also helps reduce the incidence of fungal and bacterial diseases. The most common reason for plants dying in high-rise residences is lack of sunlight. Try our guide to vertical gardening if you are short on space.
Soil available locally is often clayey, drains poorly and retains too much moisture. Prepare your own by mixing at least two parts of gritty material, such as fine-grade lightweight expanded clay aggregate pellets (LECA), with one part of mature compost and one part of commercial loamy soil mix. The large particle size of fine LECA pellets “opens up” the growing mix, permits excess water to drain away freely and allows the root zone to dry out quickly between each watering.
Water potted herbs thoroughly enough that the excess drains from the base of the pot. Avoid using saucers, as they are a dengue risk. Water herbs once or twice daily; sunnier and windier locations may require more frequent watering. To check the soil, use your index finger to feel for moisture below the soil surface. Water only when the potting mix is on the slightly dry side.
Avoid over-feeding. For most herbs, use a few pellets of slow-release fertiliser (Osmocote, for example) and a weekly foliar spray of dilute seaweed extract.
For more helpful tips head to our living in Singapore section.