Cape leadwort

Cape leadwort: how do you recognise it?

Habit

Semi-climbing, evergreen shrub with long, flexible branches; up to about 3 m if you tie it in, often 1–2 m in a tub. About 1.5 m wide.

Leaves

Light green, oblong to spoon-shaped, 3–6 cm, with a slightly wavy edge. In winter it loses part of its foliage.

Flowers

Sky-blue, tubular flowers with five lobes, in dense clusters at the tips of the shoots, from June to October. White forms also exist.

Calyx

The calyx below the flower is covered in sticky glandular hairs, to which small insects can stick.

Roots

Fibrous and branching; it needs a large pot with good drainage.

Flowering: June–October · Plants: May–June · Pruning: March

Why grow it?

• Sky-blue flowers from June to October: a rare, fresh colour on the summer terrace.
• It attracts butterflies, which like to land on the flower clusters.
• It grows fast and flowers in its first season, even as a young plant in a pot.
• It can be grown as a shrub, as a semi-climber on a trellis or as a free-standing tub plant.
• Easy to shape by pruning and simple to propagate from cuttings.

Cape leadwort: where does it grow best?

• Full sun and warmth: a sunny, sheltered terrace or a south- or west-facing wall. In part shade it flowers less.
• Humus-rich, free-draining soil: sand or loam, acid to chalky. In a pot, good potting compost with some sand.
• Keep evenly moist in summer, never soggy: give a pot drainage holes and a layer of clay pebbles at the bottom.
• Sheltered from strong wind, which snaps the long branches.
• Use a pot at least 30–40 cm wide and give a trellis, mesh or obelisk as support for the flexible branches.

Light

Sun

Soil type

Sand or loam

Acidity

Not fussy

Moisture

Normal

Size

3 m tall, 1.5 m wide

Hardiness

Half hardy (to -2 °C): protect it in harsh winters

Goes well with

• Pelargonium: Pink, red or white flowers next to the sky blue, and also a terrace plant that overwinters frost-free.
• Marguerite daisy: White or yellow daisies that stand out nicely against the blue.
• Lantana: Warm yellow-orange flowers, also a butterfly plant in a pot.
• Lavender: A sun-loving neighbour with fragrant, grey-green leaves.

Cape leadwort: when and how to plant it?

Plant in May–June.

1. Put it outside in May–June, after mid-May, when nights no longer fall below 5–8 °C.
2. Choose a pot or tub at least 30–40 cm wide with drainage holes and put a layer of clay pebbles in the bottom.
3. Use good potting compost with 10–20% sharp sand or perlite for good drainage.
4. Plant at the same depth as in the old pot, fit the trellis or obelisk at the same time and tie in the first shoots loosely.
5. Water in generously straight away, let the excess drain away and, if you like, add a layer of bark or grit on top.

Care

Water

In summer water regularly, sometimes daily in hot weather; let the top layer dry out slightly between waterings. In winter hardly any, just enough to stop the root ball drying out.

Feeding

From April to September give a high-potassium flowering-plant feed every 2 weeks in the water.

Tying in

Tie the long, flexible branches to a trellis or obelisk; it does not climb well by itself and needs support.

Repotting

Every 2 years in spring, in fresh compost and a pot 5 cm larger, or just replace the top layer of compost.

Deadheading

Cut off faded clusters; this keeps the plant tidy and encourages new flower clusters.

Tip: Prune it hard in March, to 2–3 buds or by half, and tie the new shoots to a trellis. Overwinter it cool (5–10 °C), bright and with hardly any water.

Cape leadwort: when to prune it?

Pruning months: March.

When: In March, before growth starts. It flowers on young shoots, so hard pruning in spring does not cost you any flowers.

How:

• Shorten all of last year’s branches to 2–3 buds, or by half if you want a larger specimen.
• Cut dead, weak or damaged stems right out.
• Thin out overcrowded stems so light and air can get in.
• In summer you can trim long shoots and pinch out the tips for a full, branching plant.

Caution: Do not prune in autumn just before overwintering: there would then be no room for large branches in your cool space.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

July–September: semi-ripe cuttings of 10 cm, or May–June: softwood cuttings from young shoots. Lower leaves removed, in sandy compost at 20–25 °C under plastic. Roots after 3–6 weeks.

Seed

March–April at 18–21 °C, lightly covered. Seedlings grow slowly; cuttings give a flowering plant sooner.

Cape leadwort: how does it get through the winter?

Hardy to −2 °C: protect in harsh winters.

• Not hardy: it tolerates −2 °C at most, and only briefly. Bring it indoors in October, before the first night frost.
• Overwinter it bright and cool, at 5–10 °C, in a conservatory, bright stairwell or light garage; hardly any water.
• Some of the foliage drops: that is normal. Remove fallen leaves to prevent mould.
• In spring, give gradually more water and light, prune in March and put it outside again only after mid-May.

Diseases and pests

• Mealybug, scale insect and whitefly: White, woolly patches, sticky shoots or small white flies, especially during overwintering. Wipe or rinse off with lukewarm water, move it somewhere cooler and hang up yellow sticky traps.
• Spider mite: Fine webs and yellowing leaves in dry, warm air. Rinse and move the plant somewhere cooler and airier.
• Yellow leaves: Too much water, too little light, or iron deficiency on chalky soil. Water less, give more light and use soft water, preferably rainwater.
• Root rot: Limp, yellowing leaves from wet roots. Free-draining compost, a pot with holes and hardly any water in winter.

Through the year

• January: Rest. Cool and light, hardly any water.
• February: Check for mealybug, aphids and spider mite.
• March: Prune. Repot or replace the top layer of compost.
• April: Water more. Start feeding.
• May: Put outside after mid-May. Tie in.
• June: First flowers. Feed every 2 weeks.
• July: Full flower. Water. Take cuttings.
• August: Flowering. Water. Semi-ripe cuttings.
• September: Flowering. Water less. Last feed.
• October: Last flowers. Bring indoors before the first night frost.
• November: Cool and bright, little water.
• December: Rest. Check now and then for aphids.

Good for wildlife

Butterflies

Nectar for butterflies.

Did you know?

• The name Plumbago comes from the Latin plumbum, ‘lead’, and the English name leadwort refers to it.
• Plumbago belongs to the Plumbaginaceae, the family of sea lavender (Limonium).
• The sticky glandular hairs on the calyx sometimes trap small insects.