Recently a client asked me for a list of trees that could be grown in containers, as she wanted to add height and interest to soften some angular corners on her house. Having made the recommendations, I thought it would be good to share them here, for others to use as needed.
Trees will grow more slowly in containers, allowing more vigorous species to be enjoyed without the risk of them taking over the garden or generating too much shade. Trees in containers can be very useful for screening unwanted views or ugly features where the ground conditions are not suitable for in-ground planting, or on areas of hard landscaping.
There are, however, some KEY REQUIREMENTS for success, which include:
1. Use as large a container as possible, so long as it is in proportion to the size of the tree (30-40L min. for larger species)
2. Choose a tree that is a good size and that has a good form, for instant impact
3. Be prepared to water frequently, or to set up an automated watering system. Adding a surface mulch of gravel or decorative pebbles helps to reduce water loss and keep weeds at bay
4. Top dress with fresh compost mixed with slow release fertiliser each spring to ensure a continued supply of nutrients.
5. Think about the microclimate of the pot and choose a tree to suit the conditions.
6. The choice of compost is VERY IMPORTANT. Use a soil based compost such as John Innes No 3 or other mature plant compost brands as this is heavier (helping to stop pots from toppling over in the wind) and holds water for longer.
The following fast-growing trees are worth a try if you need height:
- Betula utilis var. jacquemontii (Himalayan Birch) – try 3 in pot for best effect
- Amelanchier lamarckii (Snowy Mespilus)
- Prunus serrula (Tibetian Cherry) – looks good with 3 in a pot
- Sorbus varieties, such as vilmorinii, cashmiriana, ‘Chinese Lace’ (Rowans)
- Malus (Crab Apple), especially the ornamental varieties
- Prunus (Flowering Cherry), especially the ornamental varieties
- Fruit trees (grown on dwarfing root stocks)
For slower/lower-growing trees try:
- Gingo biloba (Maidenhair Tree)
- Acer palmatum varieties (Japanese Maple) – needs a sheltered spot
- Fagus sylvatica ‘Purpurea Pendula’ (Weeping Purple Beech)
- Pinus mugo, especially the dwarf cultivars such as ‘Mops’ – evergreen
- Buxus sempervivens (Box) – evergreen and good for making topiary shapes (the two pictures above show Buxus balls and cloud-pruned Buxus, respectively)
Growing trees in containers is also a good solution if you want to grow species which may not be happy in your soil or may not be hardy enough to survive the winter months. Examples include citrus trees, which need to be moved into a frost-free conservatory or greenhouse to survive winters in Scotland. It is also a good idea to protect potted Bay trees in colder areas, especially the standard forms with a clear stem.
So, have a go and see what pleasure you can gain from growing trees in pots!