Repotting guide

When & how to repot Lobbi Japanese Cedar (Cryptomeria japonica 'Lobbii')

Also called Lobbi Japanese Cedar, Lobbii Japanese Cedar, Cryptomeria 'Lobbii'.

More about lobbi japanese cedar

About Lobbi Japanese Cedar

Cryptomeria japonica 'Lobbii' · also called Lobbi Japanese Cedar, Lobbii Japanese Cedar · flowering

Cryptomeria japonica 'Lobbii' is a stately, fast-growing cultivar of Japanese Cedar with densely arranged, bright green foliage and a strongly conical to columnar habit. It is more compact than the species type, with tightly clustered branchlets. Suitable for large gardens and parks in temperate oceanic climates with high rainfall.

Mature size: 15–25 m tall, 4–6 m wide (50–80 ft × 13–20 ft)

How to tell lobbi japanese cedar needs repotting

Repotting on a calendar is less reliable than reading the plant. For lobbi japanese cedar, 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 lobbi japanese cedar 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 lobbi japanese cedar

Every 2–3 years; top-dress in the in-between years. Lobbi Japanese Cedar's growth habit — strongly conical to columnar evergreen tree with densely clustered, cord-like branchlets and spirally arranged, awl-shaped foliage. more compact and tidier than the straight species. — sets the pace. Cryptomeria japonica 'Lobbii' is a stately, fast-growing cultivar of Japanese Cedar with densely arranged, bright green foliage and a strongly conical to columnar habit. It is more compact than the species type, with tightly clustered branchlets. Suitable for large gardens and parks in temperate oceanic climates with high rainfall.

What size pot to step lobbi japanese cedar up to

Move up exactly one pot size. A heavy lobbi japanese cedar 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 lobbi japanese cedar

Early spring, just as new growth restarts, is the ideal window for lobbi japanese cedar. 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 lobbi japanese cedar

Consider top-dressing first. If lobbi japanese cedar 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 deep, moist, fertile, 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 lobbi japanese cedar in the same spot and light — moving and repotting at once is what makes it drop leaves.

Aftercare

Leave lobbi japanese cedar 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 lobbi japanese cedar

Lobbi Japanese Cedar wants deep, moist, fertile, acidic to neutral loam. Thrives in deep, humus-rich, slightly acidic soils (pH 5.5–6.5). Amend with composted bark or leaf mould before planting. Tolerates clay if drainage is reasonable. Avoid alkaline, thin, or dry soils which cause yellowing (chlorosis) and stunted growth. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting lobbi japanese cedar — frequently asked questions

How often should you repot lobbi japanese cedar?

Every 2–3 years; top-dress in the in-between years for lobbi japanese cedar. Fully repot lobbi japanese cedar 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 deep, moist, fertile, 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 lobbi japanese cedar need?

When is the best time of year to repot lobbi japanese cedar?

Should you top-dress or fully repot lobbi japanese cedar?

For a big, heavy lobbi japanese cedar, 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 lobbi japanese cedar after repotting?

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