Travelers to the tropics are no doubt familiar with the pandanus or screw pine. These plants are frequently seen growing just inland from the sea, in boggy or wet areas, or along streams or riverbanks.
The large trunks are whorled, with a spiral crown of leaves emerging from the top. The leaves are still and pointed, sometimes reaching several feet in length and frequently striped or variegated (depending on the species). Moreover, the leaves are all armed with wicked and painful spines, so casually grabbing a pandanus leaf is not something you’re likely to forget.
In their native habitat, pandanus are spreading, broad trees that can sometimes reach a height of 15 to 20 feet and a width of 20 feet or more (again, depending on the species). Given this description, they don’t seem like the most likely of indoor plants, and indeed they aren’t. However, once established, even small pandanus are relatively tough plants and will survive drought-like conditions. Moreover, they are a lovely symbol of the tropics.
How to Care for Pandanus
The trick to growing pandanus inside is to provide plenty of warmth and humidity and patience. They are not fast-growing, which helps explain why larger specimens are so prized throughout the tropics.
Pandanus thrives in dappled sunlight to direct sunlight. In the summer, non-acclimated plants should not be exposed to direct sunlight to prevent scorching. In the winter, provide as much light as possible.
Pandanus can be drought-tolerant, especially when they get a little bit older. However, plants with a regular supply of water are better off, with more attractive leaf coloration and vigor. In the winter, when the plant will likely go into dormancy, you can dramatically reduce the water.
A rich, peat-based potting soil with excellent drainage is beneficial. They grow well in somewhat sandy conditions.
Feed with a weak liquid fertilizer throughout the growing season. Cut fertilizer back to once a month or so in the winter.
Temperature and Humidity
During the summer months, water regularly and mist frequently. In the winter, do not expose them to cold drafts or temperatures below about 55 F.
In their native habitats, pandanus plants are natural clumpers. Over time, older plants will begin to send out suckers, or plantlets, from their base. If you want to encourage a large mass of plants, let them grow. If you want to propagate the plant, wait until the plantlet is about 6 inches long, then remove it by cutting as close to the main stem as possible. Treat with a rooting hormone for the best chances of success and provide with plenty of warmth.
Potting and Repotting
Repot in the early spring, when the growing season begins. Overall, because you don’t want your plant growing into a room-swallowing monster, you should repot only when strictly necessary, perhaps every two or three years. Be careful when repotting, as the plant's spines can cause a painful scratch.
The overall pandanus genus contains about 600 species, which are distributed throughout the Old World tropics. In warmer climates, it is possible to find a decent selection of pandanus in garden centers, including a truly wonderful dwarf species that stays less than two feet tall. In colder climates, where pandanus is a true novelty, your selection is likely to be limited to P. veitcheii or P. sanderi. The main difference between these two is their leaf coloration: P. sanderi has yellow leaf striations while P. veitcheii has white striations.
Common Pests and Plant Diseases
They are not especially vulnerable to pests but keep a lookout for mealybugs, aphids, and mites. Signs of infestation include tiny webs on plants, clumps of white "powdery" residue, or visible insects on the plant. Treat infestations as soon as possible to prevent them from spreading to the rest of your collection.