How you overwinter a bonsai depends primarily on its origin. Native and Asian tree species tolerate frost and can overwinter in the open air. A change of location is recommended for tropical indoor bonsai that are sensitive to cold. Read the best tips about winter quarters and care in this bonsai guide.
How should you care for a bonsai in winter?
How to overwinter bonsai? Protect outdoor bonsai on the balcony in a wooden box, sink outdoor bonsai in the garden and keep indoor bonsai bright and cool. Domestic and Asian tree species tolerate frost, tropical indoor bonsai require special attention.
Outdoor bonsai overwinter on the balcony
The most beautiful outdoor bonsais come from the motherland of Asian tree art. Japanese hornbeam (Carpinus japonica) or Japanese maple (Acer palmatum) tolerate light frost. From -5° Celsius there is a risk of frost damage. Many Asian bonsai beauties in pots can still overwinter outside on balconies and terraces if you take these protective precautions:
- Cover wooden box on the floor with bark mulch
- Place the bonsai with pot on the mulch layer
- Pour coconut soil or similar peat substitute up to the top of the tree
- Cover the box with air-permeable fleece (€34.00 on Amazon) or breathable mulch film
Place the winter box with the bonsai in a partially shaded corner protected from the wind. Please check weekly whether the substrate in the bowl needs to be watered.
Outdoor bonsai overwinter by sinking
Willow (Salix), cornelian cherry (Cornus mas) or field maple (Acer campestre) are native tree species that are hardy down to -40° Celsius and are the ideal outdoor bonsais. However, in the limited substrate volume of a bonsai pot, winter hardiness reaches its limits. Sinking into the warming garden soil solves the problem. This is how you properly overwinter an outdoor bonsai:
- Place the outdoor bonsai with pot on a table
- Clean the substrate surface of moss and impurities with a coarse brush
- Wrap the bowl with jute ribbon in several layers including the base of the trunk
- Dig a pit in a shady, wind-protected location
- Lay the pit bottom with vole wire
- Cover wire mesh with soil
- Place the bonsai in the pit and press lightly
- Fill the pit with soil
Sink the bonsai into the bed just below the first branch. Please complete the digging work with your hands. Shovel or spade could damage or break the delicate branches.
Overwinter indoor bonsai bright and cool
Bonsai gardeners prescribe a change of location for the indoor bonsai for the winter. Birch fig (Ficus benjamini), June snow (Serissa foetida) and other tropical tree species do not tolerate the dark season in the heated living room. The consequences are stunted growth, pests and epically long horny shoots. It doesn't have to come to this if you overwinter an indoor bonsai like this:
- Relocate to a bright location with temperatures between 10° and 15° Celsius
- Do not fertilize bonsai in winter quarters
- Watering sparingly without causing dryness of the bales
- Spray the trees from time to time with lime-free water at room temperature
Reserve a place for your indoor bonsai in the slightly temperate greenhouse or winter garden from October onwards. The mini tree likes to look decorative in the bright, cool bedroom.
Tip
A planted garden bonsai bravely remains in its original place in the bed in winter. Japanese girl pine (Pinus parviflora), Chinese juniper (Juniperus chinensis) and other bonsai in XXL format overwinter outside without any special protective measures. Please only water from time to time when there is a frost and there is no rain or snow to provide water.
