Repotting guide

When & how to repot Full Moon Maple (Acer shirasawanum 'Aureum')

Also called golden full moon maple.

More about full moon maple

About Full Moon Maple

Acer shirasawanum 'Aureum' · also called golden full moon maple · flowering

Golden full moon maple is a slow, refined deciduous tree with rounded, fan-pleated chartreuse-gold leaves that glow through summer and flush orange-red in autumn. Unlike palmate Japanese maples its foliage holds bright golden colour well, but only in dappled light. It needs shelter, even moisture, and free-draining acidic soil to avoid scorch.

Mature size: Typically 4-6 m tall and 3-5 m wide over many years; compact and slow, especially in containers.

Watch for — Slow establishment: Grafted full moon maples are slow and resent root disturbance. Plant in autumn or spring, water consistently, and be patient through the first few seasons.

How to tell full moon maple needs repotting

Repotting on a calendar is less reliable than reading the plant. For full moon maple, watch for these signs:

Thick roots out of the drainage holes, or circling the surface and lifting the plant.
The pot dries out unusually fast and full moon maple wilts between waterings it used to shrug off.
The plant is visibly top-heavy and tips over easily.
Stalled growth and small new leaves over a full season — though with a big specimen, top-dressing is often the better first response before a full repot.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot full moon maple

Every 2–3 years; top-dress in the in-between years. Full Moon Maple's growth habit — slow-growing, rounded to broadly spreading deciduous small tree with horizontally layered branches and distinctive circular, pleated leaves. — sets the pace. Golden full moon maple is a slow, refined deciduous tree with rounded, fan-pleated chartreuse-gold leaves that glow through summer and flush orange-red in autumn. Unlike palmate Japanese maples its foliage holds bright golden colour well, but only in dappled light. It needs shelter, even moisture, and free-draining acidic soil to avoid scorch.

What size pot to step full moon maple up to

Move up exactly one pot size. A heavy full moon maple dropped into a vastly bigger pot sits in a reservoir of wet soil its roots cannot reach, which rots them and destabilises the plant. In the years between repots, lift off and replace the top 3–5 cm of soil (top-dressing) instead — it refreshes nutrients without the shock of a full repot.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot full moon maple

Early spring, just as new growth restarts, is the ideal window for full moon maple. The plant is moving into its strongest growth phase and re-roots into fresh soil quickly. Avoid repotting in winter dormancy or, for flowering plants, while it is in bud or bloom — recovery is slowest then and you risk dropping the flowers.

Step-by-step: repotting full moon maple

Consider top-dressing first. If full moon maple is not badly root-bound, scrape off and replace the top 3–5 cm of soil instead — far less shock for a big plant that hates moving.
Get help and one size up. For a full repot, choose a pot just one size larger. A heavy plant needs two people and a stable, free-draining pot.
Ease it out on its side. Lay the plant down, slide the pot off, and gently loosen the outer roots. Do not bare-root a mature specimen.
Repot at the same depth. Add fresh moist, humus-rich, free-draining acidic to neutral loam beneath and around the rootball, keeping the original soil line. Firm it so the trunk is stable and upright.
Water and leave it put. Water thoroughly, then leave full moon maple in the same spot and light — moving and repotting at once is what makes it drop leaves.

Aftercare

Leave full moon maple in exactly the same spot and light it was in before — moving and repotting at the same time is what makes a big specimen drop leaves. Water it in well, then let the top of the soil dry before watering again so the larger volume of fresh soil does not stay sodden. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for full moon maple

Full Moon Maple wants moist, humus-rich, free-draining acidic to neutral loam. Wants fertile, moisture-retentive yet free-draining soil that is slightly acidic. Avoid heavy waterlogged clay and shallow chalky ground; improve with leaf mould or composted bark. Use an ericaceous loam mix for pots. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting full moon maple — frequently asked questions

How often should you repot full moon maple?

Every 2–3 years; top-dress in the in-between years for full moon maple. Fully repot full moon maple only every 2–3 years; in the in-between years just top-dress the top 3–5 cm of soil. Step up one pot size in spring with moist, humus-rich, free-draining acidic to neutral loam. It is heavy and hates being moved, and a vastly oversized pot holds water against the roots and rots them.

What size pot does full moon maple need?

When is the best time of year to repot full moon maple?

Should you top-dress or fully repot full moon maple?

For a big, heavy full moon maple, top-dressing — replacing the top 3–5 cm of soil — is the gentler option most years, with a full repot only every 2–3 years. A mature specimen sulks and drops leaves when fully repotted, so do it as rarely as the roots allow.

Should you fertilise full moon maple after repotting?

Not immediately. Wait about 4 weeks after repotting full moon maple. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.