The “robusta” in the name gives hope that the Washington palm will somehow survive all the adversities of the winter. But hope is a bad advisor here. Since the plant comes from warm Mexico and the south of the USA, we should rely on knowledge.
Is Washingtonia robusta hardy?
Washingtonia robusta is only partially hardy and can withstand temperatures down to -3 °C. In severe frost, frost damage or even death of the palm tree is possible. It is therefore recommended to spend the winter in a frost-free, cool and bright winter quarter, e.g. B. in a winter garden or greenhouse.
The palm tree can tolerate some cold
Anyone who observes the growth of this palm tree will notice that it continues to sprout its palm fronds even at temperatures between 5 and 10 °C. That's why she's allowed to stay outside not only in summer, but also for a large part of spring and autumn. But what about winter?
If there is frost, it will soon be over
If the thermometer drops to -3 °C, everything is still okay because the palm tree can still withstand this light frost. However, the temperature must not fall any further, otherwise the following scenario threatens:
- Freeze damage to leaves is unavoidable up to -8 °C
- If it gets frostier than -8 °C, the palm tree will die
Since this palm is not completely hardy, it should grow in this country as a mobile potted plant that only spends the frost-free season outdoors.
Overwintering in winter quarters
A plant that has so little winter hardiness is only in good hands in suitable winter quarters from the first night of frost. You should overwinter Washingtonia robusta with reduced care as follows:
- frost-free and as cool as possible
- with incidence of light
- z. B. in the winter garden or greenhouse
- with watering as needed
- but without fertilizer, otherwise it will have yellow leaves
A warm winter is also not ruled out. However, warm heating air combined with low humidity and a lack of light in winter weakens the palm tree. As a result, diseases and pests have an easier time spreading.
Tip
Water the palm tree more often in warm, heated rooms. Additionally, you should increase the humidity by regularly spraying the plant with water.
Outdoor Survival
In the case of potted palms and very young specimens, the lack of winter hardiness regularly leads to them freezing to death outside in winter. However, in mild regions of the country, an older Washingtonia can be planted in a protected location. Then it needs further winter protection so that it survives:
- Palm tree and top substrate layer must be heated
- z. B. with a transportable, heated greenhouse (€49.00 on Amazon)
- or a heating coil around the trunk
- additionally wrap palm fronds with fleece
