Repotting guide

When & how to repot large-flowered butterwort (Pinguicula grandiflora)

Also called large-flowered butterwort, greater butterwort.

More about large-flowered butterwort

About large-flowered butterwort

Pinguicula grandiflora · also called large-flowered butterwort, greater butterwort · houseplant

A cold-hardy European carnivorous perennial native to the limestone mountains of Ireland, western France, and northern Spain, Pinguicula grandiflora produces showy violet-blue flowers up to 2.5 cm across in late spring. It forms winter hibernacula and tolerates hard frost, making it one of the few butterworts suited to outdoor temperate gardens.

Mature size: Rosette 5–12 cm (2–5 in) across; flower scapes to 15 cm (6 in) tall

Watch for — Root rot in warm conditions: P. grandiflora is intolerant of warm nights above 18°C for extended periods. In warm indoor rooms it declines rapidly. Ensure adequate cooling and airflow; this species is best grown cold and cool, not as a typical tropical houseplant.

How to tell large-flowered butterwort needs repotting

Repotting on a calendar is less reliable than reading the plant. For large-flowered butterwort, 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 large-flowered butterwort) 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 large-flowered butterwort

Only every 2–4 years, when genuinely crowded. large-flowered butterwort 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. Cold-temperate rosette-forming perennial; produces winter hibernacula (tight, non-carnivorous resting buds) at the base through which it overwinters, even when frozen solid..

What size pot to step large-flowered butterwort up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. large-flowered butterwort 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 large-flowered butterwort 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 large-flowered butterwort

Early spring, just as new growth restarts, is the ideal window for large-flowered butterwort. 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 large-flowered butterwort

Confirm it actually needs it. Slide large-flowered butterwort 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 large-flowered butterwort 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 acidic peat-free carnivorous plant mix, 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 large-flowered butterwort 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 large-flowered butterwort

large-flowered butterwort wants acidic peat-free carnivorous plant mix. Use two parts peat (or peat-free equivalent sphagnum fibre), one part silica sand, one part perlite, and one part vermiculite. The mix should be permanently moist and low in nutrients — avoid any compost with added fertiliser. A bog garden with peaty, poorly drained, acid soil works well for outdoor planting. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting large-flowered butterwort — frequently asked questions

How often should you repot large-flowered butterwort?

Only every 2–4 years, when genuinely crowded for large-flowered butterwort. Only repot large-flowered butterwort 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 acidic peat-free carnivorous plant mix. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does large-flowered butterwort need?

When is the best time of year to repot large-flowered butterwort?

Does large-flowered butterwort like to be root-bound?

Yes — large-flowered butterwort 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 large-flowered butterwort after repotting?

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