Hardy palm trees can in principle overwinter outdoors. This is possible without any problems in mild regions. In cold areas, however, the plants have difficulty coping with long-lasting frosts and humidity. That's why they can't do without good winter protection. In principle, there are various ways to overwinter hardy palm trees. Potted plants are usually overwintered differently than planted specimens. In this article you will get tips on how to prepare hardy palm trees for the winter and get them through the cold season well.
Frost sensitivity
There is no general value for frost resistance for hardy palm trees. For each type of palm tree there is an individual temperature specified that the plant can just about tolerate. However, these are only approximate values and also depend on a variety of factors. Small and younger palms are more sensitive to frost, especially during long periods of frost. The roots of these palm trees do not reach as deep into the ground and therefore freeze more quickly than the long roots of older plants. Since the palm tree can no longer transport water, it will ultimately not freeze but dry out.
- the roots are most sensitive
- The trunk can tolerate slightly cooler temperatures
- The leaves are significantly less sensitive
If individual leaves die during the winter, this is usually not a problem. The vegetation point, the so-called palm heart, must be protected from moisture in some palm trees.
Tip 1
A palm tree evaporates water through its fronds all year round. That's why a functioning water balance is important even in winter.
Planted palm trees
Proper winter protection for planted palm trees begins with choosing the right location. The palm tree should be planted as protected as possible from cold winds and heavy rain. There is also a good microclimate on a southern house wall. All hardy palm trees require at least three months of winter rest. During this time, the plant reduces its metabolism to a minimum. In contrast to perennials, for example, their above-ground plant parts do not die.
Root protection
The roots of palm trees are particularly sensitive to moisture and cold. Therefore, they must be provided with appropriate protection early in the fall.
Tip 2
Hardy palms such as the hemp palm are very sensitive to moisture. Since autumn and winter are usually wet in our latitudes, the soil around the root area must be covered with a thick layer of bark mulch. This layer should be at least 20 to 30 cm thick.
Tip 3
If the palm tree is in a place where it is exposed to damp weather, something urgently needs to be done to combat heavy rainfall. In this case, a light roof makes sense.
Trunk protection
Winter protection for the trunk is only necessary in the rarest of cases. Only in cool regions does this need to be wrapped with a reed or bamboo mat.
Leaf protection
When the first slight sub-zero temperatures are approaching, it is time to prepare the hardy palm tree for winter. The best way to protect the fronds from moisture and cold is to carefully tie them together. It is cold in the homeland of these palm trees, but it is a dry cold. That's why the plants there get along completely without winter protection. In our case, however, the sensitive heart must be protected from moisture.
- carefully tie the leaves upwards with a coconut or sisal rope
- pad the inside (funnel) with straw
- Wrap the crown with a permeable winter fleece
- don't wrap too tightly, otherwise the fronds will break off
- the fleece should be as light and translucent as possible
- tie with a rope
- Tie garbage bags to the top as rain protection
Tip 4
If it rains persistently, it is necessary to completely protect the crown of leaves from moisture with foil or a waterproof bag. If the weather becomes drier again, this film must be removed again, otherwise the air cannot circulate and mold and rot will develop inside.
Remove antifreeze
Winter protection should be removed as soon as the temperatures warm up again. Since the leaves are not particularly sensitive to frost, this can happen early in spring as long as there is no damp weather.
Conditionally hardy species
Conditionally hardy palm trees or plants that are planted in very cold regions should be prepared for winter when planting. If this has not happened, the plant must either be dug up during the cold season and left overwintered in a bucket frost-free. Alternatively, you can follow this step with a little effort.
- Dig up soil around the root ball at a distance of about 40 cm
- Insert 5 cm thick hard foam panels
- on all four sides
- do not place a plate under the palm tree
- Lay a heating cable on the panels (inside) in a spiral shape
- Heating cables are suitable for gutters or water pipes
These heating cables are usually connected to a control device that has a temperature sensor. If the temperature drops below 5 degrees, the antifreeze kicks in. There is no risk of this heating device generating excessive heat.
Strong winter protection
In particularly cold regions it may be necessary to wrap the entire palm tree with bubble wrap with particularly large air chambers. To do this, the leaves of the palm tree must first be loosely tied together.
- Wash in the rods or slats loosely around the palm tree at a distance of 10 cm
- the film must not be attached directly to the palm tree
- at least a hand's width distance
- must extend beyond the crown
- Attach the film to the frame
- install an air flap at the top and bottom
- ventilate in warmer temperatures
- Protect the root area with a thick layer of bark mulch
- possibly wrap a rope of light around the trunk and place it on the ground
- switch on when it is frosty (or set to continuous operation using the temperature sensor)
Even stronger protection is almost like a heated greenhouse and a lot of effort. That's why every hobby gardener should consider in advance whether the effort is worth it. It is easier to dig up the plant and overwinter it as a potted plant.
potted plants
The wintering of hardy palm trees that are grown in pots is a little different. These plants cannot tolerate high temperatures in their winter quarters because living spaces are generally too dark. In this case, the palm trees would not hibernate and would quickly become ill or even die due to the lack of light and dry air.
Time
Frost-resistant palm trees should be left outside as long as possible. However, it is important that the plants are grown in a relatively large container that does not freeze completely so quickly. When the first light frosts occur, the bucket is placed on a Styrofoam plate and insulated with two to three layers of bubble wrap. The root system of palm trees is much more sensitive than the above-ground parts of the plant, which is why it must be provided with winter protection relatively early on. Be sure to place the plant in a protected place on a house wall.
Tip 5
The potted plants must be put away if temperatures fall below freezing for a long period of time. This is also necessary in the case of light frosts that last for days, as there is a risk that the root ball will freeze completely. If the night temperatures drop sharply for a short period of time, the plants can stay outside. You can use the following temperatures as a guide, up to which the individual palm varieties are considered frost-resistant (only for a short period of time):
- Brahea armata (Blue Hesperides palm): -10 degrees
- Butia paraguayensis (Dwarf Yatay Palm): -11 degrees
- Butia yatay (Yatay palm): -10 degrees
- Caryota maxima (Himalayan fishtail palm): -7 degrees
- Chamaerops humilis (European dwarf palm): -13 degrees
- Chamaerops humilis var. Cerifera (blue dwarf palm) – 11 degrees
- Dypsis decipiens (Madagascar royal palm): -8 degrees
- Jubaea chilensis (honey palm): -15 degrees
- Phoenix canariensis (Canary Island date palm): -6 degrees
- Phoenix dactylifera (real date palm): -9 degrees
- Phoenix rupicola (cliff date palm): -6 degrees
- Phoenix theophrasti (Crete date palm): -12 degrees
- Rhapidophyllum hystix (needle palm): -22 degrees
- Sabal mexicana (Mexican Sabal palm): -11 degrees
- Sabal minor (dwarf palmetto palm): -20 degrees
- Serenoa repens green (green saw palmetto): -12 degrees
- Trachycarpus fortunei (Chinese hemp palm): -18 degrees
- Trachycarpus latisectus (windamer palm): -12 degrees
- Trachycarpus martianus (hemp palm): -8 degrees
- Trachycarpus nanus (Yunnan dwarf palm): -18 degrees
- Trithrinax campestris (Blue Needle Palm): -15 degrees
- Washingtonia filifera (Washington palm): -8 degrees
- Washingtonia robusta (Petticoat Palm): -7 degrees
Tip 6
If you want to make sure that you keep the time to clear away, simply insert a minimum-maximum thermometer into the soil close to the edge of the bucket. As soon as the night temperature falls into the minus range and does not rise back into the positive range during the day, it is time to relocate frost-resistant palm trees.
Tip 7
One of the worst mistakes that hobby gardeners can make is to place the palm tree that was previously left cold outside directly into the warm living room. In cool temperatures, the roots of the palm tree can hardly absorb water. This is not a problem outside because the plant's metabolism is reduced to a minimum (hibernation). When putting away large pots, it takes a long time for the root ball to warm up again. However, the leaves quickly rise to the ambient temperature and evaporate more water.
The episode:
The plant suffers from a lack of water and dries up. It is even more damaging to suddenly put the palm tree outside in the cold after a few days of getting used to the apartment.
Tip 8
If you want to overwinter your hardy palm indoors because there is no suitable winter quarters, you should bring the plant indoors before the nights outside get cold. Once the palm tree is used to the temperature drops of day and night outdoors, moving it to a heated apartment and the associated temperature shock can cause the plant problems.
Tip 9
Once the hardy palm tree is put away in the pot, it should definitely stay there until next spring. The otherwise robust plant cannot tolerate constant, strong temperature fluctuations.
Various winter quarters
Winter-hardy palm species definitely need to take a break from vegetation. This should last at least three months. If the palm tree is warm all year round, it may not take this vegetation break until spring when it is put back outdoors. This can cause serious damage to the plant because if the metabolism is at a low level, the palm cannot evaporate enough moisture in sunshine and warm temperatures and will burn.
Winter Garden
A cool, frost-free winter garden is ideal as a home for hardy palm trees. However, the temperatures should not be too high. Around 5 to 10 degrees is ideal. The winter garden may not be heated and therefore may not be used for residential purposes.
Staircase
In a bright stairwell, the temperatures are usually moderate and the lighting conditions are sufficient for wintering. However, most stairwells are quite drafty. The palm tree does not tolerate cold drafts well.
Greenhouse
Greenhouses are ideal for overwintering hardy palm trees. However, certain requirements must be met:
- Shading option during long periods of sunshine
- Heating to prevent long lasting frosts
If the sun shines for several days or weeks in winter, a greenhouse can heat up significantly. In this case, the palm ends its winter rest and sprouts again. If it gets colder again, there is a risk of frostbite on the young shoots.
Basement
Overwintering the palm tree is only an option in basement rooms that are cool enough. Cellars used as living space or very well insulated new basements are usually too warm. Temperatures around 10 degrees are ideal. However, the palm tree must not be kept too dark because it does not die in winter, but simply slows down its metabolism. And to do this it needs sufficient amounts of light. In contrast to specimens that overwinter warmly, the amount of light is limited.
Tip 10
Install additional lighting and control it via a timer. Since only a few artificial light sources emit a spectrum similar to that of sunlight, not all types of lamps are suitable.
- Incandescent lamps: not suitable (too high red content)
- Sodium vapor lamp (energy-saving lamps): only emit one wavelength, unfortunately this is not suitable for plants
- Fluorescent tubes: whether normal or special plant fluorescent tubes, the light color cold white emits a similar spectrum to sunlight and is therefore well suited
The lighting duration should be around 12 hours at low light intensity.
Pouring
Because the hardy palm tree goes into a resting phase, it requires much less water than in the growing season. That's why the root ball must never be too wet. Both outside and in the winter quarters, you should only water when the soil has already separated from the edge of the pot. For outdoor plants, make sure that they are not directly exposed to the rain. A sheltered place under a roof protects them from waterlogging.
Fertilize
As long as the palm trees are in hibernation, they should not be fertilized. The palm tree hardly uses any nutrients during this time, so adding additional nutrients would lead to undesirably high s alt and nutrient concentrations in the root area. These damage the roots.
Conclusion
Making hardy palm trees winter-proof always requires a little effort. Depending on the type of palm tree, the plants can tolerate more or less frost. However, the roots of all palm tree species are very sensitive to frost. In addition, the winter-hardy palm trees react sensitively to moisture, both at the roots and at the growing point in the crown. Therefore, the plants must be protected from moisture and ground frost.
