Plumbago care in full sun, from pruning to winter
Plumbago is an evergreen shrub from South Africa that flowers sky blue from summer into autumn, on stems it grew that same year. It belongs in full sun on a sheltered balcony or terrace. This page covers the sun, the watering, the spring cut that keeps it small, the winter and the sap that irritates skin.
- Full sun on a sheltered balcony or terrace. In shade it makes leaves and few flowers.
- Cut it back in late winter or early spring. The flowers come on the new stems.
- Wear gloves to prune it, because the sap irritates skin.
What plumbago is, and what else is sold under the name
Plumbago auriculata, also sold as Cape leadwort or under its older name P. capensis, is an evergreen shrub from South Africa with thin arching stems and pale green leaves. The RHS gives it 2.5 to 4 metres of height and describes the flowers as sky blue and long-tubed, in clusters at the stem tips.
The stems scramble rather than stand, so left alone the shrub leans on whatever is next to it. NC State Extension says it can be tied in and trained like a climber. The plant care guide lists the other species in this library with the light each one needs.
| Name on the label | What it is | Flower | Same care? |
|---|
| Plumbago auriculata, Cape leadwort | The species this page covers | Pale sky blue | Yes |
| Plumbago ‘Alba’ | A white cultivar of the same species | White | Yes |
| Plumbago ‘Imperial Blue’ | A blue cultivar of the same species | Blue | Yes |
| Chinese plumbago, Ceratostigma willmottianum | A different genus in the same family | Blue | No, and its safety listing does not apply here |
Does plumbago need full sun?
Yes, if you want flowers. NC State Extension rates it for full sun, which it defines as six hours or more, and for partial shade. UF/IFAS Extension says it needs full sun for its best growth and flowering, so in part shade it keeps growing and sets fewer flowers.
Wind decides the spot as much as sun does. The RHS lists south, west and east facing aspects and a sheltered exposure, so a sunny corner that funnels wind is the wrong wall for the long thin stems.
Indoors it only overwinters. NC State and the RHS both describe a pot brought into a bright, sunny room for the cold months, and a room set back from the window does not give it enough light to flower. If you have no sunny outdoor wall, indoor flowering plants covers the species that rebloom on a windowsill.
Watering plumbago in a pot or a wall pocket
Water when the top of the soil is dry, checked with a finger to the first knuckle. Sun sets the pace. A pot on a south facing wall in July dries far faster than the same pot in October, so any fixed day of the week is wrong for most of the year.
The RHS says to water freely while it is growing and to keep it barely moist while it rests in winter. What it does not take is roots sitting wet. A small volume of soil in full sun moves between dry and wet faster than a garden bed, which is why the finger test matters more on a balcony.
A week away in summer is the real risk for a sunny pot. DIY drip irrigation compares the bottle, bucket and tubing setups that keep one going while you are gone.
Soil and feeding for a plumbago that flowers
A free-draining mix and regular food while it grows. NC State lists sandy, well-drained soil, and the RHS a peat-free, loam-based compost for pots, at any pH.
- The mix. Peat-free loam-based compost with a handful of coarse sand through it, so water runs through rather than collecting at the bottom.
- Feeding. A balanced liquid feed once a month while it is in growth, as the RHS recommends, and none while it rests. UF/IFAS ties feeding in the growing season to continuous flowering.
- Repotting. The RHS repots or top-dresses in spring, which is the same week you prune.
When to prune plumbago, and how hard
Prune in late winter or early spring, before new growth starts. It flowers on the stems it grows that season, so NC State and the RHS put the main cut there, and the shortened shoots branch and form flower buds by summer.
The RHS places it in pruning group 12, where you shorten the side shoots to three or four buds from the permanent framework of branches. Through summer you can take off any stem that runs too long, which UF/IFAS says is fine at any time of year. Shearing the whole shrub like a hedge removes most of the flowers.
- Put on gloves before you cut anything.
- Take out dead, damaged and crossing stems at their base.
- Shorten each remaining side shoot to three or four buds from the main framework.
- Feed once new shoots show, and pinch out any that run long during summer.
Is plumbago frost hardy? Winter on a balcony
No. The RHS rates it H2, tolerant of low temperatures but not of being frozen, a band it puts at 1 to 5 °C. NC State gives USDA zones 9a to 11b. A cool winter outdoors is fine, and frost kills the top growth.
In the ground, UF/IFAS reports that plants cut down by a freeze usually grow back from the roots in spring. A pot or a pocket has no ground around the roots, so do not count on that recovery there. If your winters bring frost, move the plant into a bright, cool room before the first one and water it sparingly until spring.
Where winters stay frost-free it stays out all year on a sheltered wall. Any tips a cold night blackens come off at the spring prune.
Is plumbago toxic to people, cats and dogs?
It is a skin irritant first. NC State Extension rates it medium poison severity, names plumbagin as the toxic principle and lists irritation, redness and blistering after contact with any part of the plant. The RHS flags it as a skin irritant too. Wear gloves to prune and repot, and wash any sap off your arms.
For pets, the RHS lists it as harmful if eaten, except for the ripe fruit. A veterinary guide on IVIS judges it unlikely to be a problem for pets and names salivation, vomiting and diarrhoea as the likely signs. If a cat or dog has chewed it and shows those signs, call your vet.
The ASPCA has no entry for this species. The non-toxic listing that comes up for Chinese plumbago is Ceratostigma, a different plant, and it says nothing about the Cape shrub on your balcony.
Plumbago on a balcony wall
A young plant fits a pocket and a mature one does not. In the ground it grows into a shrub of several metres, so a pocket keeps it small only through the spring cut. Move it to a large pot once the roots fill the space and the spring prune no longer holds it. If you want a sunny wall without that cut, succulents take the same light.
The canvas works outdoors on a sheltered balcony or terrace, which is where this plant belongs. Only the wooden board has to stay out of standing rain, so choose a wall under an overhang that still gets the sun. Design your canvas lets you lay out a board on your own wall first.
The Medium pocket holds 1.8 litres of substrate, and that small volume in full sun is why the finger test comes before every watering. The board hangs by a slot near its top on one wall hook, so the wall side is one screw, one plug and one drilled hole.
- Put on gloves and take a young plant out of its pot.
- Loosen the root ball with your fingers until it fits the pocket.
- Sit it in, fill around it with substrate and press lightly.
- Water slowly, in measured amounts, until the substrate is evenly damp.
Plumbago problems and how to fix them
Most of what goes wrong comes from too little sun or the wrong cut, and both show as a plant full of leaves with no flowers. Pests come second. The RHS names red spider mite first, and spider mites explains the pale speckling and fine webbing they leave on the leaf.
Whitefly is the other pest the RHS names, and UF/IFAS adds scale. A cloud of tiny white insects lifting off when you brush the plant is whitefly, and whiteflies covers what clears them.
| What you see | Why | The fix |
|---|
| Plenty of leaves, few or no flowers | Too little direct sun, or the whole plant sheared over | Move it into full sun and shorten side shoots only in early spring. |
| Long bare stems sprawling out of the pocket | No spring prune, so it grows toward its shrub size | Cut side shoots back to three or four buds in late winter. |
| Yellow leaves | A mineral shortage in alkaline soil, or roots kept wet | Let the top dry before watering and switch to a feed with trace elements. |
| Pale speckled leaves, fine webbing underneath | Red spider mite | Rinse the leaf undersides with water and keep the plant apart from others. |
| Tiny white insects fly up when touched | Whitefly | Hang a yellow sticky trap beside it and treat the leaf undersides. |
| Blackened shoot tips after a cold night | Frost | Leave them on until spring, then cut back to healthy wood. |
If the leaves are yellowing and nothing in the table fits, yellow leaves reads the pattern on the leaf to separate water, light and age.
How to propagate plumbago from a cutting
Semi-hardwood cuttings in midsummer are the RHS method, taken from this year’s stems once they are firm at the base and still soft at the tip. The RHS roots them with bottom heat, which at home means a heated propagator or a warm spot out of direct sun.
- Wearing gloves, cut a side shoot of this year’s growth that has no flowers on it.
- Trim just below a leaf joint and strip the lower leaves.
- Push it into a gritty, peat-free cutting compost and water it in.
- Cover with a clear bag or a propagator lid, out of direct sun, with gentle bottom heat.
- Pot it on once new leaves show that it has rooted.
A rooted cutting is the right size for a pocket. Take a few in summer and you have the replacement ready for the year the parent outgrows its spot.
Can plumbago grow indoors all year?
Not as a flowering plant. NC State and the RHS treat it as a pot brought into a bright, sunny room for winter and put back outside for the growing season. Indoors all year it keeps its leaves and flowers poorly, because no room gives it the sun of an open south facing wall.
Does plumbago climb on its own?
No, it scrambles, so it only goes up a support you tie it to. The RHS lists the stems as needing support, and NC State says they can be trained like a vine, which is how it covers a trellis or a railing. Left untied it forms an arching mound.
Is plumbago drought tolerant?
Once it is established in the ground, yes. NC State tags it drought tolerant and UF/IFAS calls it moderately drought tolerant after establishment. A pot or a wall pocket holds far less soil than a bed, so that tolerance does not carry over and you water whenever the top is dry.
Can you grow plumbago from seed?
Yes. The RHS sows it in spring at 13 to 18 °C, and NC State lists seed as the recommended method. A cutting gives an exact copy of the parent, which matters if you want a named cultivar such as the white Alba.
How long does plumbago flower?
From summer into autumn, NC State says, and all year where it never gets cold, which UF/IFAS reports for frost-free gardens. Every flush comes on new growth, so feeding through the season and shortening spent tips keeps new flowering stems coming.
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