Juglans ailanthifolia
Japanese walnut, Heartnut
Also known as Juglans sieboldiana
- Height × spread
- 18m × 12m
- Position
- Full sun
- Hardiness
- Very cold to -20C (RHS H6)
- Flowers
- Spring, Autumn
Availability
Please ask in store about availability
Many plants are seasonal. Call 01234 567890 to check current stock.
About this plant
This handsome foliage tree has huge, spreading, pinnate leaves that are rich, glossy, green. The length of the entire leaf can exceed 0.5m (2ft), with about seventeen oblong leaflets on each one. The tree itself forms a broad and dense dome with impressively outreaching branches. There are female flowers with red stigmas in spring and, later, small sticky fruits. In autumn the foliage is pale-yellow.
- Flower colour
- Red
- Foliage colour
- Green
- Autumn foliage
- Yellow
- Variegated
- No
- Scent
- No
- Shape
- Dome
- Height
- 18m
- Spread
- 12m
- Height in 10 years
- 5m
- Spread in 10 years
- 3m
- Season of interest
- Spring, Autumn
- Flowers in
- Spring, Autumn
- Evergreen
- Deciduous
- Sun or shade
- Likes full sun, tolerates part shade
- Soil type
- Clay, Loam (normal)
- Soil pH
- All types
- Drainage
- Moisture retentive soil, Well drained soil
- Hardiness
- Very cold to -20C (RHS H6)
- Borders & containers
- Borders
- Use for
- Architectural
- Hazards
- No
Spring
Spring - late · Outdoors
Feed young plants with slow release fertiliser
Spread a slow release fertiliser around the base of the plant to the edge of the foliage spread, so that it can feed the roots. It is helpful for this to be applied for several years.
This is a simple way to provide a nutrient boost until the plant becomes well established.
Spring-Autumn · Outdoors
Water to keep the soil moist
For best results, this plant needs soil that is always moist. Water deeply and regularly as soon as soil appears dry. Even for established plants in the ground, a dry week can cause problems with some soils. Check plants in pots more often, especially in hot weather. Or install an automatic irrigation system which will do the hard work for you, even when you are away on holiday.
Without regular watering some plants never fully regain their beauty.
Summer
Summer - late · Planting
Prune to maintain the tree
Keep the plant looking attractive and healthy by removing dead branches, branches that cross or rub each other, and those which spoil its appearance.
Prune in late summer as the tree is less likely to be damaged, or to begin to bleed from the wood that has been cut.
Planting & general
Outdoor planting · Planting
Add root growth stimulant to the planting hole
Mycorrhizal fungi helps roots establish quickly, so they absorb water and nutrients more efficiently. It comes as a powder, granule or gel. Add to the planting hole or container, and to the plant's rootball before planting in the hole. For "bareroot" plants use a gel.
Planting
Protect & support young trees
Attach a newly planted tree or tall shrub over 1m to a tree stake to give support and prevent windrock. Use a tree guard to stop tree bark being eaten by animals, especially in areas with deer - removing bark injures a tree and in worst case can kill it.