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Repotting guide

When & how to repot Tuberous Cranesbill (Geranium tuberosum)

Also called Tuberous Cranesbill, Tuberous-Rooted Cranesbill.

More about tuberous cranesbill

About Tuberous Cranesbill

Geranium tuberosum · also called Tuberous Cranesbill, Tuberous-Rooted Cranesbill · flowering

Geranium tuberosum is a spring-flowering cranesbill native to the Mediterranean basin east to Iran, growing from small underground tubers. It behaves like a spring ephemeral: finely divided foliage emerges in late winter, lilac-pink veined flowers appear in spring, and the whole plant retreats into summer dormancy by early summer. The most important care fact is to provide a sunny, sharply drained position and allow the soil to dry out completely in summer — wet summer soils rot the tubers. ASPCA's toxic 'Geranium' entry refers to Pelargonium; true Geranium cranesbills are not individually listed as toxic, but ASPCA does not confirm them as non-toxic either, so treat with caution around pets.

Mature size: 15–20 cm tall and 20–30 cm wide in flower; foliage disappears entirely by midsummer.

How to tell tuberous cranesbill needs repotting

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

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 tuberous cranesbill

Lift and divide every 3–4 years once clumps congest. Rather than a true repot, tuberous cranesbill is lifted and divided once the clump congests and flowering drops off. Tuberous-rooted clump-forming geranium with a spring ephemeral habit, dying back to underground tubers by early summer..

What size pot to step tuberous cranesbill up to

Pot size matters less than depth and spacing here. When you replant tuberous cranesbill, set the bulbs or tubers at the correct depth (a rough guide: two to three times their own height of soil over the top) and space them so they are not touching. A wide, shallow pot suits a clump better than a tall narrow one.

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 tuberous cranesbill

The only safe window is dormancy: wait until the foliage has yellowed and died back naturally, lift and divide then, and replant before or at the start of the next growing season. Disturbing tuberous cranesbill in full growth or flower sets it back badly.

Step-by-step: repotting tuberous cranesbill

  1. Wait for dormancy. Let tuberous cranesbill foliage yellow and die back completely. Lifting while it is in growth wastes the energy it is storing for next year.
  2. Lift carefully. Loosen the soil well away from the bulbs/tubers with a fork and ease the whole clump out without spearing them.
  3. Separate the offsets. Gently pull the clump apart into individual bulbs or tubers. Keep only firm, healthy, blemish-free ones.
  4. Replant at the right depth. Reset them in fresh well-drained to dry; chalk, loam or sandy at the correct depth and spacing — not touching — so each has room to bulk up.
  5. Water in and rest. Water once to settle them, then keep on the dry side until growth resumes. Do not feed until leaves are actively growing.

Aftercare

After replanting tuberous cranesbill, keep the soil barely moist — not wet — until shoots appear; bulbs and tubers rot in cold, saturated soil. Once leaves are growing strongly, resume normal watering. Hold off feeding until the plant is in active growth again.

The right soil mix for tuberous cranesbill

Tuberous Cranesbill wants well-drained to dry; chalk, loam or sandy. Sharply drained, even gritty or sandy soil is essential; this species tolerates poor fertility but will not tolerate waterlogged or moisture-retentive soils in summer. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting tuberous cranesbill — frequently asked questions

How often should you repot tuberous cranesbill?

Lift and divide every 3–4 years once clumps congest for tuberous cranesbill. Tuberous Cranesbill is lifted and divided, not "repotted". Every 3–4 years, once the foliage has died back and it is dormant, lift the clump, separate the offsets, and replant at the correct depth in well-drained to dry; chalk, loam or sandy. Crowding, not pot size, is what reduces flowering over time.

What size pot does tuberous cranesbill need?

Pot size matters less than depth and spacing here. When you replant tuberous cranesbill, set the bulbs or tubers at the correct depth (a rough guide: two to three times their own height of soil over the top) and space them so they are not touching. A wide, shallow pot suits a clump better than a tall narrow one. Use our pot size calculator to size it from the plant's current pot and root spread.

When is the best time of year to repot tuberous cranesbill?

The only safe window is dormancy: wait until the foliage has yellowed and died back naturally, lift and divide then, and replant before or at the start of the next growing season. Disturbing tuberous cranesbill in full growth or flower sets it back badly.

Do you "repot" tuberous cranesbill, or lift and divide it?

You lift and divide it. Tuberous Cranesbill grows from bulbs or tubers, so instead of repotting you wait for dormancy, lift the congested clump, separate the healthy offsets, and replant them at the right depth and spacing. Doing this every 3–4 years restores flowering.

Should you fertilise tuberous cranesbill after repotting?

Hold off feeding tuberous cranesbill until it is in active growth again. Fresh soil already carries enough nutrients to get it re-established, and feeding disturbed roots too soon does more harm than good.

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