Repotting guide

When & how to repot Achimenes (Achimenes longiflora)

Also called hot water plant, Achimenes, widow's tears.

More about achimenes

About Achimenes

Achimenes longiflora · also called hot water plant, Achimenes · flowering

Achimenes longiflora, the hot water plant, is a tropical rhizomatous gesneriad that explodes into violet-blue, trumpet-shaped flowers all summer above soft, hairy leaves. A relative of the African violet, it grows from tiny scaly rhizomes, blooms profusely in warmth and bright indirect light, then dies back to overwinter dormant. Steady warmth and even moisture are key, as a check in growth can stall flowering entirely.

Mature size: 20-45 cm tall; trailing types cascade 30-60 cm in a hanging basket.

Watch for — Leaf scorch and spotting: Direct sun burns the soft leaves, and cold droplets on the hairy foliage leave pale marks. Filter strong light and water at the soil with tepid water.

How to tell achimenes needs repotting

Repotting on a calendar is less reliable than reading the plant. For achimenes, 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 achimenes) 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 achimenes

Only every 2–4 years, when genuinely crowded. Achimenes 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. Bushy to trailing rhizomatous perennial with slender stems and soft hairy leaves, suiting pots, baskets and edging. Grows each spring from small scaly rhizomes and dies back completely to them each winter..

What size pot to step achimenes up to

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

Early spring, just as new growth restarts, is the ideal window for achimenes. 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 achimenes

Confirm it actually needs it. Slide achimenes 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 achimenes 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 light, humus-rich, free-draining 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 achimenes 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 achimenes

Achimenes wants light, humus-rich, free-draining mix. A loose, moisture-retentive but well-drained medium such as a peat-free houseplant or African violet mix with added perlite. Start the rhizomes in shallow, airy compost in spring. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting achimenes — frequently asked questions

How often should you repot achimenes?

Only every 2–4 years, when genuinely crowded for achimenes. Only repot achimenes 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 light, humus-rich, free-draining mix. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does achimenes need?

When is the best time of year to repot achimenes?

Does achimenes like to be root-bound?

Yes — achimenes 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 achimenes after repotting?

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