How to Grow Pandan in Temperate Climates

Pandan plant (Pandanus amaryllifolius) (Chinese Name : 班兰) is a tropical plant native to South East Asia. It’s a perennial evergreen tree with fragrantly-scented leaves, growing into a small shrub 1 – 1.6 m tall when the leaves are harvested often, or a small tree 2 – 4.5 m tall in it’s tropical native habitat. Picking the leaves prevents it from growing into a tree form and keeps it small. The plant eventually forms an upright trunk, with a canopy of long, strappy leaves with thick aerial roots hanging down from the trunk.

How Pandan is Used

Pandan leaves are used in South-East Asian cuisine to wrap chicken, pork, fish and glutinous rice before they are barbecued or steamed to impart the distinct and unique flavour, which is described as being a milky-sweet, floral-rose-almond-vanilla-like.The fresh or frozen leaves need to be be bruised or boiled to release their flavour, and dried pandan leaves are described as having little to no flavour at all.

In soups and stews, the leaves are tied in a knot and placed in the food as it’s cooking to give flavour and fragrance. In many dishes the leaves are cut into large pieces and cooked with the food, then removed afterwards, as they are fibrous and inedible. Pandan leaf is also used to flavour curries in Balinese, Malaysian, Sri Lankan and Thai cooking.

Fresh leaves are also used in cakes and other desserts, confectioneries (such as agar jellies) and drinks. The fresh leaves are crushed or boiled to extract the green chlorophyll pigments, which are used to colour foods bright green. Commercially produced pandan extract can also be purchased for the same purpose.

This versatile plant is also used medicinally, infusions of the leaf are used as a calming sedative for restlessness, while infusions of pandan leaf in coconut oil are rubbed on the skin to treat rheumatism. The roots contain the compound 4-hydroxybenzoic acid which is a potential anti-diabetic drug.

More than just culinary, pandan leaves have pest repellent properties too, they contain the compound 2-acetyl-1-pyrroline which is a repellant to the American cockroach (Periplaneta americana) and German cockroach (Blattella germanica).

Growing Conditions for Pandan

Being a tropical plant, pandan doesn’t like too much sun or wind, and is best grown in a protected, part-shade position. A position that gets direct morning sun and a bit of dappled midday sun is ideal, but keep it away from hot afternoon sun! It’s also drought and frost tender, which means that the plant wont survive dry conditions or low temperatures, so keep the soil moist during the warm seasons and protect it from the cold. In fact, if the temperature falls below 10 C°(50 F°), the plant is best moved indoors for protection in cooler climates, as the plant is damaged by temperatures of 7 C°(44.6 F°) and below.

In its natural environment, pandan prefers light well drained, moderately fertile soils. In cooler climates, grow pandan in a pot with a good quality potting mix.

Temperate Climate Warm Season: Since tropical plants grow in climates which have hot, wet, humid summers and drier cool seasons, ensure that the pandan plant is kept moist (but not wet) during hot weather periods. Do not sit the plant pot in a saucer of water, that will rot out the roots. You can use a spray bottle to mist the leaves on hot days to maintain humidity around the plant, or sit the plant on a humidity tray (see below) to maintain humidity around the plant. Having other plants around the pandan will also provide protection from winds and increase the humidity levels. During spring and summer pandan can be grown outside in a protected spot. Locate the plant on the east side of the house where it will mainly get morning sun, use shade-cloth (50% screening grade) to reduce the effects of sun and wind when the plant is in a more exposed location.

Temperate Climate Cool Season: When the weather begins to cool down, it’s important to reduce the amount of water, keep the soil just moist, as tropical plants dislike wet soil in cold weather. When overnight temperatures fall to 10 C°(50 F°) or below, bring the plant indoors. When day and night temperatures remain cold, keep the plant indoors until the weather warms up again. Make sure that the plant pot is placed in a location which receives good light during the day, don’t place it too close to the window, as it’s colder near the glass in winter, especially at night!

It’s important to choose the right indoor location for growing pandan, most houses have heating systems, such as ducted heating, which blows hot, dry air – this will provide the warmth but dry out and kill a pandan plant. Either choose a room with good light and no heating duct, such as a laundry perhaps, or use a humidity tray to keep the humidity levels high around the plant. Once again, you can use a spray bottle to lightly mist the plant leaves to maintain humidity levels around the plant, or sit the plant on a humidity tray to maintain humidity around the plant. If the pandan plant is kept in a cold room, don’t wet the leaves as water will sit in the spaces between the leaves and the stem, become cold water and rot the stem.

Any sudden or extreme change in growing conditions will stress a plant, so it’s best to make any changes gradually. If a pandan plant has been kept indoors through autumn and winter, gently acclimatize it to outdoor conditions in spring by placing it in a shady, wind-free protected location for an hour or two, and gradually increase the time outside every few days. Once the plant has adjusted to outdoor conditions, remember to monitor the overnight temperature forecasts, and to bring the plant indoors if the nights get cool!

How to Repot a Pandan Plant to Avoid Overpotting

When repotting any plants, avoid potting them in an overly large pot, it is better to move them up to the next pot size only.

If a small plant is placed in a much larger pot, the small root system won’t be able to take up all the water, so the bulk of the potting medium will stay wet. Many plants don’t like constantly wet growing conditions, as this can cause the roots to rot. Pandan plants definitely don’t like excess water in the cooler seasons in temperate climates, they like to be kept barely moist.

When a small plant is placed in a very large pot, this is called overpotting – don’t overpot pandan plants, if they need to be transplanted to a larger pot, select a pot that is the next size up, and only transplant in the warmer seasons when the plant is actively growing, the best times are from spring through to early summer.

In the picture above, the pandan plant in a 50mm forestry tube has been transplanted into a 100mm wide seedling pot, next pot size will be 15cm wide, then 20 or 25cm, depending on the size of the plant. Going from a 50mm forestry tube to a 15cm wide pot would still be fine as long as it’s not too late in summer, just ensure that the plant has enough growing time to extend its roots into the pot.

When transplanting or repotting plants, its a good idea to water them with seaweed extract (sold as Seasol in Australia), as it contains compounds called cytokinins, which are plant root growth stimulating hormones, they help the plant establish itself better and reduce the effects of transplant shock. When repotting, transplanting or planting, use 30mL of seaweed extract in a 9 litre watering can, water once at planting time and again 1 week later.

Since pandan is a tropical plant, it grows in warm, humid conditions. It will dry out if exposed to dry heat or windy conditions. It’s easy to create humid conditions around the plant with a simple DIY humidity tray.

How to Make a Humidity Tray

Constructing a humidity tray is very simple, just take a plastic tray which can hold water, fill it with stones or pebbles, then add water below the level the top of the stones or pebbles, so that a plant pot sitting on the surface is kept out of the water below.

Water evaporating from the wet stones will increase the humidity around the plant, it’s that simple!

For the plastic tray, a deep plastic pot saucer works well, the one pictured below is filled with scoria, which is a porous volcanic rock. Shiny pebbles work just as well, it makes no difference

Larger plastic trays can hold much more plants, and aggregating a number of plants together helps retain the humidity around them.

Here’s a pandan potted up and sitting on a humidity tray. This can be placed near a well-lit window indoors, and an occasional topping up of the water is all that’s required. A regular misting would also help in heated areas with warm dry air, just keep the plant away from the heating ducts and the flow of air coming from them.

To create even more humidity around the plant, use a clear plastic storage tub, place the humidity tray and the plant inside it, the surrounding walls of the container will retain a lot more humidity around the plant.

For those who want to go a step further, it’s possible to raise the temperature a bit more too!

An electric heat mat for raising plants seedlings can be used, just sit it under the humidity tray, it will warm  the water, increase evaporation and create a nice warm humid microclimate for the pandan plant.

A heat mat with a thermostat can be set to 20°C (68°F) and left running. In winter it will switch on to maintain warmth, and will switch off during the warmer seasons. Remember to check the humidity tray for water, as it evaporates faster when a heat mat is used.

References:

National Parks Board, Singapore.Government, Flora & Fauna Web, Pandanus amaryllifolius Roxb.