Screw trees are cultivated in Central Europe exclusively as indoor or container plants. They are not hardy, come from warm countries in the eastern hemisphere and prefer to grow near the sea. There are more than 600 species. They are evergreen plants with a tree or shrub-like growth habit. Characteristic of these plants is the helical growth. The long, narrow leaves are spirally arranged like in a screw thread. In between, secondary shoots form.
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The leaves of most species are sword-shaped and can become very long. They often have serrated edges. Strong aerial roots and so-called stilt roots are also typical of the plants. These lift the screw tree out of the pot and often serve as a support for the very large and strong screw palms, as they are also called.
Pandanus tectorius is mainly used as a houseplant. These plants do very well as they do well in dry air. Pandanus furcatus is also suitable as a houseplant, but it grows very large. You have to have enough space. I particularly like Pandanus javanicus, the variety with the variegated leaves.
I myself have a Pandanus veitchii. This comes from Polynesia and is characterized by narrow, white-green striped leaves, often with white leaf margins. The leaves have rather coarse spines that can be badly scratched. Repotting actions only run with thick, long-sleeved sweaters and thick gloves.
The care of the screw tree
The screw tree is absolutely easy to care for. You have to water and fertilize, cut away a dead leaf every now and then and repot every few years. Otherwise there is not much to do. Every now and then the leaves have to be wiped with a damp cloth because they get a lot of dust. Since this is too time-consuming for me and you can also injure yourself on the prickly parts, I shower the plants. I put the small specimens in the bathtub or shower and rinse them off. I take the big pandanus to the garden and let the rain wash it clean. Rainwater has the advantage that no limescale forms. The screw tree is very easy to propagate and an ideal houseplant, as dry air usually does not cause any problems. With good care, the screw tree is up to 2 meters high and just as wide.
The screw tree likes it bright. The more light the plants get, the clearer their leaf markings can be seen. Our large screw tree is in the living room by the window, but the curtains are cream-colored and absorb a lot of light. This tree has uniformly rich green leaves almost throughout. A severed offspring standing in the bath, on the other hand, has green and white striped leaves, with a bold white border. Green is also a very healthy colour.
- Bright and inside also with sun
- The more light the plants get, the clearer their leaf markings can be seen.
- Outdoors, the screw tree must be slowly acclimated to the sun. I once put a pandanus outside during renovation work due to lack of space, he was badly burned and that was in May. In general, however, they tolerate the sun, after all they come from sunny countries.
- No temperatures below 14° C.
Compost-based soil is often recommended for the plant substrate. I use potting soil myself, but loosen it up with lava gravel or expanded clay. Gravel is also suitable for this.
- Coarse-grained soil with a very low proportion of clay and humus
- In principle, the pandanus does not place great demands on the plant substrate.
When you have to repot, you usually notice that the plants lose their footing. The supporting roots do not grow evenly and the screw trees lean in one direction or another. Initially, you can compensate for this with supports, but eventually it just doesn’t look good with four or more support sticks holding the plant. Then it’s time for the repotting.
- Do not cover the stilt roots with soil!
- The screw tree grows well in hydro vessels. I find the planters with an irrigation system even better.
- If you don’t use either of the two options, you should always use a heavy planter, because the screw tree sometimes tips to the side and a light container falls over.
- When planting and repotting, protect your hands and arms and pay close attention to your face – risk of injury!
- Do not cut off aerial and stilt roots.
- Press the soil down firmly to give the plant a hold.
- Support if necessary. If you don’t want to use sticks, you can also use decorative stones to support the stilt roots, which often just looks better. I cover the ground with white pebbles anyway because I like that better. Two or three larger white stones give stability to the whole.
- A pandanus works particularly well in a tall container, where the leaves can hang down nicely. If the plant is at ground level, the leaves are too long.
watering and fertilizing
The screw tree doesn’t really need much water. Less is often better than too much. It is important not to pour into the corners of the leaves, because the water stays there and can lead to rot. It is much better to always water down on the ground. I have my plant in a Lechuzza pot with an irrigation system. There she takes her own water as needed. I have had pandanus for more than 20 years and they have never grown better than in these vessels. However, this also means that they grow very quickly and need to be repotted almost every two years.
- Don’t water too much
- perform a finger test. The top layer of soil must be well dried.
- Many recommend keeping the soil slightly moist at all times during the growing season. I can not say that. However, the plants will actually draw more water during this time if you fill the tank regularly.
- Do not water from above so that water does not remain in the leaf axils.
- It is better to always pour into the ground below, or into the cachepot.
- If you pour into the bottom of the pot, excess water must be removed after about an hour.
- Waterlogging leads to root rot.
- Pots with an irrigation system are great. These only need to be refilled every few weeks.
- Water significantly less in winter, but never let the root ball dry out.
- Fertilize during the growing season, i.e. from April to the end of August, beginning of September. About every four weeks I add liquid fertilizer for green plants to the irrigation water or the water box.
Not much needs to be cut. However, whole leaves die off on the outside while new ones form in the middle. It is better to cut out these old leaves once they are completely dry. If you don’t want to wait that long because the brown parts don’t look really good, you can always cut off the brown tips of the leaves. However, you should always leave the last 2 millimeters green and not cut into the healthy tissue.
- If necessary, remove the child, otherwise the plant will take on large proportions even more quickly.
- I always stick a lot of kindel, so the pandanus looks denser at the bottom. You don’t see any earth. In the end it’s a matter of taste though.
The screw tree spends the winter best in a warm room, with temperatures around 20° C. It is watered less than in summer. However, the bale should not dry out. Because of the often lacking humidity, the pandanus can be sprayed with water from time to time. It is best to use rainwater. There is no fertilization.
Propagation is extremely easy. The plant reproduces itself. It constantly forms small side shoots. You can leave them on the plant to make them big and stately, or you can separate them. I always put them in a glass of water to root, but have also read that they can be planted straight away, then in a substrate of equal parts peat and sharp sand. The interfaces should be dried with charcoal powder. In addition, you put a bag over the plant and the container to ensure a high level of humidity. I leave the separated plants for a day so that the separation point dries up and put the plants (usually a lot) in a glass jar. I read somewhere that you should use a blue glass jar for rooting.
diseases and pests
The screw tree is very robust. In the 20+ years that I’ve been caring for these plants, I’ve only thrown one out once because it was full of mealybugs. They had settled in the area of the stilt roots and I hadn’t noticed. They had multiplied so much that I had given up picking them off. I have a few screw trees and there are always offspring. So I saved myself the work. Otherwise, these plants grow and thrive magnificently and every now and then I have to give one away because there is no longer enough space. The plant then has 2 x 2 meters. Companies are always happy to have such large plants for their foyer.
- Brown leaf tips usually appear when too little has been poured. I use this fact as follows. On my giant pandanus, the leaves are overgrowing the water gauge tube. So if I forget to add water, the tips of the leaves turn a bit brown. Since this starts with the side shoots, often with whole brown leaves, the emergency is felt before the mother plant is affected. Then it’s poured.
- Brown leaf tips can also come from dry air. Spraying the plant with water helps here.
- I read that dry air also causes lice. Except for the mealybugs, I’ve never had any problems.
- Cool temperatures and too much moisture, or a combination of both, can quickly lead to root rot.
For me, the screw tree is an absolutely easy-care houseplant. Sufficient light and sufficient water in summer are important. Otherwise, there is not much to do, especially when cultivating in hydro or containers with an irrigation system. If you are looking for a fast-growing, decorative and easy-care plant, the screw tree is recommended.