Repotting guide

When & how to repot Cobaea scandens (Cobaea scandens)

Also called cup and saucer vine, cathedral bells, Mexican ivy.

More about cobaea scandens

About Cobaea scandens

Cobaea scandens · also called cup and saucer vine, cathedral bells · flowering

Cobaea scandens, the cup and saucer vine, is a fast, tender perennial climber usually grown as an annual for its large bell-shaped flowers that open creamy-green and age to deep purple, each set in a leafy green ruff. It climbs rapidly by branched tendrils, flowers from summer to first frost, and quickly covers trellis, arches or fences in a single season.

Mature size: Up to 4-6 m in a single season, scrambling over arches, trellis and fences.

Watch for — All leaves, few flowers: Too much nitrogen or too little sun drives lush foliage with sparse bloom. Grow in full sun, keep feeding lean, and switch to a high-potash fertiliser.

How to tell cobaea scandens needs repotting

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

Roots circling the bottom of the module or pot, or poking out of the drainage holes.
The seedling dries out within a day and growth has visibly stalled.
Roots are white and matted in a tight spiral when you tip the plant out.
It has outgrown its current container for the stage of the season — pot cobaea scandens on before it becomes hard root-bound.

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 cobaea scandens

Pot on seedlings as they grow; not a perennial repot. Cobaea scandensis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Vigorous tender perennial climber grown as an annual; grips by branched leaf tendrils and produces dense, fast cover in one season..

What size pot to step cobaea scandens up to

Pot cobaea scandens on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check.

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 cobaea scandens

Pot cobaea scandens on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.

Step-by-step: repotting cobaea scandens

Pot on before it is root-bound. Check cobaea scandens regularly; move it up as soon as roots reach the edge of the cell or pot, not after they have circled.
Step up one or two sizes. Choose the next container up — not a giant one. Cold, wet, unused soil around a small root system stalls seedlings.
Knock it out gently. Support the stem, tip the pot, and ease the rootball out without breaking it. A little teasing of circled roots at the base is fine.
Pot into rich mix. Set it into fresh moderately fertile, free-draining soil at the same depth (tomatoes are the exception — they can go deeper to root along the stem).
Water in and grow on. Water well, keep it in good light, and resume feeding once it is established and growing again.

Aftercare

Water cobaea scandens in well and keep it in bright light; a freshly potted-on seedling can wilt for a day while roots settle, so do not overcompensate by drowning it. Do not fertilise for about 1 week — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for cobaea scandens

Cobaea scandens wants moderately fertile, free-draining soil. Grows in most well-drained soils; overly rich ground produces lush foliage and fewer flowers. A loam-based compost suits container plants. Tolerates a range of pH. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting cobaea scandens — frequently asked questions

How often should you repot cobaea scandens?

Pot on seedlings as they grow; not a perennial repot for cobaea scandens. Cobaea scandens is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into moderately fertile, free-draining soil so the roots never circle the cell, ending in a large final container. A root-bound transplant stalls and never fully recovers.

What size pot does cobaea scandens need?

When is the best time of year to repot cobaea scandens?

Can you put cobaea scandens straight into a much bigger pot?

No. Even a fast-growing cobaea scandens should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise cobaea scandens after repotting?

Not immediately. Wait about 1 week after repotting cobaea scandens. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.