Repotting guide

When & how to repot Sweet Clockvine (Thunbergia fragrans)

Also called Sweet Clockvine, White Lady, White Clock Vine, Fragrant Thunbergia.

More about sweet clockvine

About Sweet Clockvine

Thunbergia fragrans · also called Sweet Clockvine, White Lady · flowering

Thunbergia fragrans is a twining annual or short-lived perennial vine producing a generous display of sweetly fragrant white 5 cm flowers through warm months. More compact and refined than its blue cousins, it suits trellises, fences, and hanging baskets in sunny gardens. Tolerates both sun and light shade.

Mature size: 2–4 m tall in a season; spread determined by support structure

How to tell sweet clockvine needs repotting

Repotting on a calendar is less reliable than reading the plant. For sweet clockvine, 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 sweet clockvine 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 sweet clockvine

Pot on seedlings as they grow; not a perennial repot. Sweet Clockvineis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Twining perennial vine, usually grown as a warm-season annual in temperate climates.

What size pot to step sweet clockvine up to

Pot sweet clockvine 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 sweet clockvine

Pot sweet clockvine 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 sweet clockvine

Pot on before it is root-bound. Check sweet clockvine 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 well-draining loamy or sandy soil with organic matter 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 sweet clockvine 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 sweet clockvine

Sweet Clockvine wants well-draining loamy or sandy soil with organic matter. Thrives in a free-draining mix of loam, compost, and coarse sand (2:1:1). Tolerates moderately poor soils. In containers, use a quality peat-free multi-purpose compost. pH 6.0–7.0 is ideal. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting sweet clockvine — frequently asked questions

How often should you repot sweet clockvine?

Pot on seedlings as they grow; not a perennial repot for sweet clockvine. Sweet Clockvine is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into well-draining loamy or sandy soil with organic matter 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 sweet clockvine need?

When is the best time of year to repot sweet clockvine?

Can you put sweet clockvine straight into a much bigger pot?

No. Even a fast-growing sweet clockvine 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 sweet clockvine after repotting?

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