African hemp

African hemp: how do you recognise it?

Habit

Fast-growing, upright shrub with soft, later woody stems; 1.5–2 m tall and up to 1.5 m wide indoors.

Leaves

Large, 10–25 cm, heart-shaped with a few lobes and a toothed edge; soft green and velvety.

Flowers

Loose, umbrella-shaped clusters of white flowers with yellow and purple-red stamens at the heart. February to May.

Stamens

They move outwards when you touch them gently: a fun detail to show children.

Roots

Fibrous and vigorous: the pot fills with roots quickly, so repot regularly.

Flowering: February–May · Plants: March–April · Pruning: May

Why grow it?

• Grows fast: within a few years a generous, lush houseplant of 1.5–2 m.
• The big, soft leaves give a fresh, almost tropical feel indoors.
• Flowers in winter and early spring (February–May), when almost nothing flowers outside.
• Easy to care for and easy to propagate from cuttings.
• Ideal for a cool, bright spot such as a stair landing, an unheated conservatory or a porch.

African hemp: where does it grow best?

• Bright, with a few hours of sun; soften strong midday sun in summer with a net curtain.
• Summer: 18–25 °C. Winter: preferably cool and bright, 5–10 °C, for instance in an unheated conservatory or stairwell.
• Light, humus-rich potting compost with a little sand or perlite for drainage; slightly acid to neutral.
• Evenly moist, watered often in summer, but never standing in water.
• Allow 50–80 cm of space all round and avoid draughts and spots right above a radiator.

Light

Sunny or bright, out of direct sun

Potting soil

Multi-purpose compost or airy, humus-rich compost

Acidity

Acid or neutral

Watering

Moderately or generously

Size

2 m tall, 1.5 m wide

Temperature

Minimum 5 °C

Goes well with

• Clivia: Also likes a cool, bright winter and flowers at the same time.
• Fatsia: Large leaves and the same cool winter quarters.
• Cyclamen: Flowers in the cool winter room and looks good next to the white flowers.
• Ivy: Evergreen and happy in a cool, bright spot.

African hemp: when and how to plant it?

Plant in March–April.

1. Repot in March–April, just before new growth starts; young plants every year.
2. Choose a pot 3–5 cm wider than the old one, with a drainage hole.
3. Put a layer of clay pebbles at the bottom and fill with light potting compost mixed with a fifth part perlite or sand.
4. Set the plant at the same depth as before and firm lightly.
5. Water until it runs out of the hole and let the surplus drain from the saucer after a quarter of an hour.
6. Put it back in a bright place and wait 4–6 weeks before feeding again.

Care

Water

In summer water generously as soon as the top 2 cm are dry: the large leaves lose a lot of water and wilt quickly. In the cool winter keep it only just moist.

Feeding

From March to September, liquid houseplant feed in the water every two weeks. None in winter.

Humidity

Copes with normal room air. Misting now and then with low-lime water keeps the leaves fresh and spider mites away.

Cleaning the leaves

Wipe the large leaves now and then with a damp cloth so more light can get through.

Putting outside

From mid-May, when night frost is over, in a bright, sheltered place, out of strong midday sun.

Repotting

Every year for young plants, every two years for older ones; otherwise renew the top layer of compost.

Tip: Turn the pot a quarter turn now and then so it grows evenly and does not lean towards the light. Take a few cuttings in summer so you always have a young spare plant.

African hemp: when to prune it?

Pruning months: May.

When: Straight after flowering, in May. This keeps the plant compact and full.

How:

• Shorten the stems to 30–50 cm above the pot, just above a leaf joint.
• Remove dead, bare or overlong stems right at the base.
• Shorten side shoots too: the plant branches and gets a dense shape.
• Use a sharp, clean knife or secateurs; the prunings can be used as cuttings.

Caution: Do not prune before or during flowering, or you will lose this season’s flowers.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Tip cuttings

April–July: take 10–15 cm cuttings from non-flowering shoots, remove the lower leaves and insert in moist cuttings compost at 20–25 °C under a clear bag. They root in 3–5 weeks.

Seed

In spring at 20–22 °C on seed compost; slower than cuttings and the plants are less predictable.

African hemp: how does it get through the winter?

• Not hardy: the minimum is 5 °C. It prefers a cool, bright winter at 5–10 °C, which helps flowering in spring.
• Water sparingly: the compost may dry out a little. From February, when buds appear, give a little more water and a little more warmth.
• In a heated room in winter it drops leaves and gets spider mites and whitefly; choose a cooler, bright spot instead.
• Bring it back indoors in October, before the first night frost.

Diseases and pests

• Leaf drop: Yellow leaves falling off come from a winter spot that is too warm, too little light or irregular watering. Move it somewhere cooler and brighter and water regularly.
• Wilting leaves: Mostly drought in summer: water generously and let it drain well. If the compost is soggy, it is too much water: let it dry out.
• Spider mites: Fine webbing and pale speckles on the leaves in dry, warm air. Rinse the plant with lukewarm water, raise the humidity and repeat after a week.
• Whitefly and aphids: Tiny white flies or aphids under the leaves. Rinse with water and hang yellow sticky traps.

Through the year

• January: Put in a cool, bright spot (5–10 °C). Little water.
• February: Flowering begins. Water a little more.
• March: Flowering. Repot if needed. Start feeding.
• April: Full flower. Feed every two weeks.
• May: Prune after flowering. From mid-May put outside in shelter.
• June: Water generously. Take cuttings.
• July: Water generously and feed.
• August: Feed. Clean the leaves with a damp cloth.
• September: Last feed. Check for aphids and spider mites.
• October: Bring in before the first night frost, cool and bright. Less water.
• November: Cool and bright. Little water.
• December: Rest. Check now and then for aphids.

Did you know?

• The stamens of the flower move outwards when touched gently, a so-called touch response.
• The name honours Anders Sparrman, a Swedish naturalist and pupil of Linnaeus, who collected plants in South Africa.
• In its homeland the plant becomes a shrub or small tree several metres tall.