The screw tree gives a winter garden an exotic atmosphere. The plant looks like a palm tree with its tuft of leaves and the aerial roots are reminiscent of mangroves. The plants have very specific requirements in terms of location and care so that they grow lushly.
How do you care for a screw tree?
A screw tree needs a bright location with a minimum lighting intensity of 900 to 1,000 lux, slightly acidic substrate with a pH value between 5.5 and 6.5 and regular watering to stay constantly moist. For optimal growth and appearance, fertilize every two weeks during the growing season.
Origin
The genus of screw trees (Pandanus) includes over 600 species. They are sometimes referred to as pandans or screw palms, although they have nothing in common with other palm family. These species belong to the screw tree family and originally come from warmer regions in the eastern hemisphere. They are native to numerous islands in the Indian Ocean and the Mascarene Islands. Here the plants colonize coastal areas and develop impenetrable vegetation.
Growth
Pandans are evergreen plants with a tree or shrub-like shape. They grow perennially and form simple or multi-branched trunks that become partially woody with age. When the humidity is very high, screw trees develop aerial roots. With the help of these roots that grow freely to the ground, the plants absorb moisture from the air. They make the actual trunk appear broad. The plants reach heights of more than 100 centimeters.
offshoot
Over time, small side shoots will appear on the trunk, which you can cut off with a sharp knife and use as offshoots. In some species, the shoots develop tiny roots on the trunk. To support wound healing, you can dust the cut site on the trunk with a little charcoal. The dust absorbs moisture and at the same time has a disinfectant effect, preventing the development of diseases.read more
leaves
The leaves of the screw trees stand in a dense clump at the end of the trunk. The leaf blade merges directly into a leaf sheath. Both midribs and leaf edges are covered in thorns. The large leaves have a simple structure and are drawn out in a linear shape. They overhang, making screw trees look like palm trees. Due to their triple spiral arrangement, the upper part appears twisted, which is how the plants got their German name.
Bloom
Pandans develop male and female flowers that differ in shape. While the male cobs are multi-branched, female cobs flowers appear simple. Flower development is very rare in indoor cultivation. Birds and insects are responsible for pollination. Screw trees are mainly pollinated by the wind.
Fruit
After successful fertilization, screw trees develop drupes that consist of several chambers. There are numerous tiny seeds in each chamber. There are some species such as Pandanus utilis that develop edible fruits.
Usage
With their picturesque growth, screw trees serve as indoor greenery. Because of their demands, they are only suitable for container planting. Pandans decorate potted gardens and tropical warm houses. The plants line artificial waterfalls and grottoes in tropical baths.
Perfect neighbors for screw trees:
- staghorn fern
- Agaves
- Flamingo flowers
- Elephant Ear
Which location is suitable?
Screw trees prefer a hot and humid climate. They thrive in a bright spot with several hours of sunshine each day. Pandans thrive when they receive sun during the morning and midday hours. The plants cannot tolerate the blazing midday sun. If you cannot offer these conditions, you should use a plant lamp (€39.00 on Amazon). Screw trees require a minimum illuminance of between 900 and 1,000 lux.
What soil does the plant need?
Screw palms thrive in a slightly acidic substrate with a pH between 5.5 and 6.5. If you use commercial compost-based potting soil, the pH value should be in this range. Deviating values lead to unhe althy growth. Mix the soil with peat or coconut fiber, sand or perlite to ensure optimal water and nutrient regulation.
With a homemade mixture you can prevent rapid substrate compaction. This saves you time because you don't have to repot it every year. Mix all ingredients thoroughly and check the pH value with indicator strips or a pH meter. If the value is too low, you can increase it by adding soil. A value above 6.5 can be reduced with acidic peat or humus substrate.
This goes into the substrate mix:
- three to five parts conventional potting soil
- 1, 5 to three parts clayey soil
- one part of quartz sand or perlite
Screw tree in a pot
Screw trees can be cultivated hydroponically or planted in containers. Since the plants become top-heavy over time and tend to tip over, you should choose a heavy pot. You can also place the planter in a larger planter and cover it with stones. Planters with irrigation systems are ideal alternatives to conventional pots.
Balcony
If the thermometer does not drop below 15 degrees Celsius at night, you can put the screw tree on the balcony. Slowly acclimate the plant to the outdoor conditions by first moving it to shadier locations. After a few days it can move to its final place in light partial shade. The more light the tree receives, the more intense the leaf markings become. In dark locations the leaves remain dark green.
Propagate screw tree
The simplest propagation method is cutting off and potting the kindles, which screw trees use to reproduce vegetatively. The cuttings are stuck in soil or placed in a water-filled vase. Use a blue colored glass as this supports root formation. When growing in soil, the humidity is crucial for successful rooting. Therefore, use it in a mini greenhouse or put a film over the container. It takes between four and six weeks for the offshoot to form roots.
Further care:
- Get young plants used to the indoor air in the next two weeks
- remove the foil for a little longer each day
- water moderately in the next two months
Watering the screw tree
When screw trees are in the growth phase, they need to be watered regularly. The pot ball should be constantly moist. The exotic plants tolerate neither drought nor waterlogging. Allow the substrate to dry superficially before each watering session. In winter, watering is more sparing so that the roots do not dry out. Use soft, room temperature water. Stale tap water is just as suitable as clean rainwater. Since the leaves quickly dry out and turn brown if the humidity is too low, you should spray the plant daily.
Fertilize screw trees properly
Between spring and summer, the screw tree enjoys fertilization every two weeks. Use a liquid complete fertilizer for green plants in a weak concentration. Excessive nutrient supply leads to faster growth. With an economical dosage you can keep your pandans small.
Cut the screw tree correctly
You can cut off the leaves of the screw tree if branches are desired. Unsightly and out-of-shape plants are shortened by half. Screw trees can be pruned down to the old wood. Use a sharp knife for non-woody shoots. Woody parts of the plant are cut off with pruning shears. If the shoot is very thick, you can use pruning shears.
Remove dead leaves regularly and make sure that the aerial roots are not damaged. You can regularly remove the secondary shoots that develop on the trunk and use them for propagation. If the children stay on the trunk and grow there, the plant increases significantly in size.
How do I transplant correctly?
If the supporting aerial roots grow irregularly and the plants lean in one direction, it is time to repot. The plant needs a larger container that provides more stability. Like all green plants, screw trees are also repotted in spring. Once the plants have reached their final size, they are no longer repotted. It is sufficient if you cover the roots on the surface with fresh substrate.
Wintering
Between October and March, growth stagnates, so you need to water and fertilize the plant less. Watering is necessary when the top layer of soil has dried out. One or two fertilizations are sufficient during the winter. You can place the bucket in a cool bedroom. The temperature should not fall below 16 degrees Celsius.
Pests
Sucking pests occur on screw trees that are improperly cared for or cultivated under suboptimal site conditions. To ensure that the plant is not damaged too much, rapid control is necessary.
Spider mites
Occasionally fine cobwebs can be seen in the leaf axils and between the thorns on the edge of the leaf. They indicate an infestation by spider mites, which prefer to spread when the air in the room is too dry. If there is a slight pest infestation, the affected leaves show yellowish-white to silver-colored spots. Severely damaged leaves turn gray-brown until they dry out completely.
Shower off infected plants and rub the undersides of affected leaves with a cloth. Place a large bag or transparent box over the plant so that the humidity is very high for the next three to four days. The moist microclimate kills the spider mites.
mealybugs and mealybugs
These pests are more common on screw trees. Small white webs that resemble cotton balls indicate an infestation. The leaves turn yellow and become shriveled. They are covered by a sticky film that provides optimal growth conditions for fungal spores. Preparations containing neem oil have proven to be effective control agents.
Tip
Pandanus species develop their full effect in tall containers, because here the leaves can hang far down. Additionally, place the vessel on a shelf. If the plant is on the ground, the leaves lie on top and look unsightly.
Varieties
- Pandanus veitchii: Leaves dark green with light longitudinal stripes, up to 100 centimeters long. The most commonly cultivated Pandanus species.
- Compacta: Pandanus veitchii variety with 50 to 60 centimeter long leaves, whitish edge stripes and clear longitudinal stripes.
- Aureus: Pandanus baptistii variety with short trunk. Leaves striped yellow-green, reminiscent of grass lilies.
