Repotting guide

When & how to repot Cape Sundew (Drosera capensis)

Also called Cape sundew, Cape rainbow plant.

More about cape sundew

About Cape Sundew

Drosera capensis · also called Cape sundew, Cape rainbow plant · houseplant

Drosera capensis is a subtropical carnivorous perennial native to the Cape region of South Africa, where it grows in open, nutrient-poor, moist peaty ground in full sun. It is one of the easiest carnivorous plants to grow, producing rosettes of strap-shaped leaves densely studded with red, gland-tipped tentacles that trap, curl around, and digest small insects. The key rule is to use only mineral-free water (rainwater, distilled, or reverse-osmosis) — tap water mineral build-up will kill it within months. Non-toxic to pets according to carnivorous plant specialist authorities; the ASPCA has not individually listed the species, so 'mildly-toxic' is applied as a precautionary classification.

Mature size: Rosettes to 15 cm tall and 15 cm wide; flower scapes reach 20–30 cm tall with multiple small pink blooms.

Watch for — Tentacle loss and leaf blackening from tap water: Dissolved minerals and chlorine in tap water accumulate rapidly in the nutrient-sensitive root zone; even brief use can cause tentacle dieback and root damage. Switch immediately to rainwater or distilled water and flush the medium with several volumes of mineral-free water.

How to tell cape sundew needs repotting

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

Only every 2–4 years, when genuinely crowded. Cape Sundew 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. Clump-forming, rosette-producing subtropical perennial; stems elongate with age and the plant self-seeds prolifically where conditions allow..

What size pot to step cape sundew up to

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

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

Confirm it actually needs it. Slide cape sundew 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 cape sundew 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 1:1 lime-free peat-free sphagnum moss and perlite (or horticultural silver sand), 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 cape sundew 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 cape sundew

Cape Sundew wants 1:1 lime-free peat-free sphagnum moss and perlite (or horticultural silver sand). The growing medium must be nutrient-free, moisture-retentive, and acidic (pH 4.0–5.5); avoid any compost, garden soil, or fertilised mixes — even a small amount of added nutrients burns roots and suppresses tentacle production. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting cape sundew — frequently asked questions

How often should you repot cape sundew?

Only every 2–4 years, when genuinely crowded for cape sundew. Only repot cape sundew 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 1:1 lime-free peat-free sphagnum moss and perlite (or horticultural silver sand). The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does cape sundew need?

When is the best time of year to repot cape sundew?

Does cape sundew like to be root-bound?

Yes — cape sundew 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 cape sundew after repotting?

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