Repotting guide

When & how to repot Anne Thomson Cranesbill (Geranium 'Anne Thomson')

Also called Anne Thomson Cranesbill, Anne Thomson Geranium.

More about anne thomson cranesbill

About Anne Thomson Cranesbill

Geranium 'Anne Thomson' · also called Anne Thomson Cranesbill, Anne Thomson Geranium · flowering

Geranium 'Anne Thomson' is a hybrid of G. procurrens and G. psilostemon bred by Alan Bremner of Orkney, closely related to 'Ann Folkard' but selected for improved heat tolerance and a more compact, less-sprawling habit. The bright chartreuse young leaves mature to mid-green, and large magenta-pink flowers with a black eye and dark veins are produced abundantly all summer. The RHS awarded it AGM status in 2005. The most important care fact is to site it in sun with well-drained soil and allow space for the trailing stems. ASPCA's 'Geranium' toxic listing refers to Pelargonium; true cranesbills are not confirmed non-toxic by ASPCA, so treat with caution around pets.

Mature size: 20–30 cm tall and 60–90 cm wide.

Watch for — Vine weevil: White grubs in the root zone cause sudden wilting; adult notching on leaf margins is the first sign — treat with Steinernema kraussei nematodes applied to moist soil in late summer.

How to tell anne thomson cranesbill needs repotting

Repotting on a calendar is less reliable than reading the plant. For anne thomson cranesbill, watch for these signs:

Roots spiralling thickly out of the drainage holes or pushing the whole plant up out of the pot.
The pot is so packed that water runs straight through in seconds and barely wets the soil.
It has split a plastic pot, or the rootball is a solid mass with almost no soil left when you slide it out.
Growth and (for anne thomson cranesbill) flowering have clearly stalled despite good light and feeding — but remember this plant likes being snug, so a little crowding alone is not a reason to 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 anne thomson cranesbill

Only every 2–4 years, when genuinely crowded. Anne Thomson Cranesbill is one of the plants that genuinely prefers a snug pot — it grows and flowers better with its roots a little restricted, so resist the urge to repot it on schedule. Trailing, scrambling deciduous perennial with a more compact and less invasive spread than 'Ann Folkard'..

What size pot to step anne thomson cranesbill up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Anne Thomson Cranesbill positively prefers a snug pot: it flowers and grows better when the roots are a little restricted. The single biggest repotting mistake here is over-potting — dropping anne thomson cranesbill into a pot two or three sizes up. All that surplus soil holds water the small root system cannot use, stays cold and wet, and rots the roots within weeks. When in doubt, choose the smaller pot.

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 anne thomson cranesbill

Early spring, just as new growth restarts, is the ideal window for anne thomson cranesbill. 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 anne thomson cranesbill

Confirm it actually needs it. Slide anne thomson cranesbill out and check the roots. Only continue if it is genuinely packed — this plant prefers a snug pot, so if there is still soil and room, put it straight back.
Pick a pot only one size up. Choose a pot just 2–3 cm wider with good drainage. Resist anything bigger; over-potting is the main killer here.
Ease it out gently. Water lightly the day before, then tip anne thomson cranesbill out, supporting the base. Tease the outer roots free only enough to stop them circling.
Repot at the same depth. Add a layer of fresh moderately fertile, free-draining but moisture-retentive, set the plant so the soil line sits exactly where it did before, and backfill around the sides, firming lightly.
Settle it in. Water once to settle the soil, then let it sit. Hold off on more water until the top of the soil dries — fresh soil around a small root system stays wet for a while.

Aftercare

Because the new soil holds more water than the old crammed rootball did, ease right back on watering — let the top of the soil dry before you water anne thomson cranesbill again, or you will rot the roots in the very pot you just moved it to. Keep it out of harsh direct sun for a fortnight. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for anne thomson cranesbill

Anne Thomson Cranesbill wants moderately fertile, free-draining but moisture-retentive. Thrives in a range of reasonably fertile garden soils that do not dry out excessively or become waterlogged; incorporate organic matter to improve moisture retention. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting anne thomson cranesbill — frequently asked questions

How often should you repot anne thomson cranesbill?

Only every 2–4 years, when genuinely crowded for anne thomson cranesbill. Only repot anne thomson cranesbill every 2–4 years, and only when it is genuinely root-bound — it flowers and grows best slightly crowded. Step up just one pot size in spring using moderately fertile, free-draining but moisture-retentive. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does anne thomson cranesbill need?

When is the best time of year to repot anne thomson cranesbill?

Does anne thomson cranesbill like to be root-bound?

Yes — anne thomson cranesbill genuinely flowers and grows best when slightly pot-bound, so do not rush to repot it. The mistake to avoid is over-potting into a much larger pot: the excess soil stays wet, the roots cannot use it, and the plant rots. Only repot every few years and only one snug size up.

Should you fertilise anne thomson cranesbill after repotting?

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