Arrowhead plant

Arrowhead plant: how do you recognise it?

Habit

A compact, upright plant at first; older plants climb or trail, with stems of 1 m or more.

Leaves

Arrow-shaped when young, 8–15 cm, often marked with cream, pale green or pink; on climbing stems larger and deeply divided into five or more lobes.

Stems

Green and pliable, with aerial roots at the nodes that help it cling.

Sap

Milky; it contains needle-shaped calcium oxalate crystals that irritate skin, eyes and mouth.

Flowers

Almost never indoors: a spadix with a greenish to creamy white spathe, typical of the arum family.

Plants: March–May · Pruning: March–August

Why grow it?

• An easy, fast grower that also does well some way from the window.
• Attractively marked, arrow-shaped leaves in green, cream or pink, all year round.
• Versatile: compact in a pot, trailing in a basket or climbing a moss pole.
• Very easy to root from cuttings, even in a glass of water.
• Tolerates partial and full shade, where many other houseplants struggle.

Arrowhead plant: where does it grow best?

• Partial to full shade, without direct sun: bright sun scorches the leaves.
• Variegated and pink varieties need a little more light, otherwise their markings fade.
• Warm: 18–26 °C, never below 12 °C. No cold draughts.
• Fairly humid air; a light bathroom or a group of plants helps.
• Out of reach of children, cats and dogs, trailing stems included.

Light

Bright, out of direct sun or low light

Potting soil

Multi-purpose compost or airy, humus-rich compost

Acidity

Acid or neutral

Watering

Moderately

Size

1 m tall, 0.5 m wide

Temperature

Minimum 12 °C

Goes well with

• Devil’s ivy: Another easy climber or trailer from the same family, for the same partial shade.
• Philodendron: Another climbing aroid; together on moss poles they make a green corner.
• Calathea: Patterned leaves that need the same warmth, humid air and shade.
• Nerve plant: A low plant with finely veined leaves for the front of a group of houseplants.

Arrowhead plant: when and how to plant it?

Plant in March–May.

1. Repot in March–May, every 1–2 years or when the roots fill the pot.
2. Choose a pot 2–4 cm wider, with a drainage hole.
3. Use free-draining houseplant compost mixed with a little perlite or fine bark.
4. If you want it to climb, put a moss or coir pole in the pot when you repot.
5. Set the plant at the same depth as before, firm lightly and water until it runs out of the bottom.
6. Wear gloves: the sap irritates the skin.

Care

Watering

Keep the compost lightly moist: water when the top 2 cm feels dry. Do not leave water in the saucer. Less in winter.

Humidity

Stand the pot on a tray of pebbles and water or among other plants. Misting is fine.

Feeding

From April to September, houseplant feed at half strength every 2 weeks.

Support

A moss pole kept moist gives the aerial roots something to grip; the leaves then grow larger.

Repotting

Every 1–2 years in spring, into a slightly larger pot.

Tip: To keep the attractive arrow-shaped leaves, regularly cut off the climbing stems: the plant stays young and compact. The cut stems easily root into new plants in a glass of water.

Arrowhead plant: when to prune it?

Pruning months: March–August.

When: From March to August, when the stems get too long or to keep it compact.

How:

• Cut long stems back to just above a node; new shoots grow from there and the plant fills out.
• Trim regularly if you want to keep the young, arrow-shaped leaves.
• Remove yellow or damaged leaves at the base of the leaf stalk.
• Use the trimmed stems as cuttings.

Caution: Wear gloves when pruning and do not touch your eyes: the milky sap irritates skin, eyes and mouth.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Stem cuttings

From April to August, cut 10–15 cm pieces of stem with at least one node and an aerial root. Put them in a glass of water or moist cutting compost in a warm, light spot. Roots form in 2–4 weeks.

Division

When repotting, divide a large plant into pieces, each with its own roots and shoots.

Arrowhead plant: how does it get through the winter?

• Indoors all year: it cannot take frost and already suffers below 12 °C.
• In winter water less and give no feed; let the top layer dry out a little more.
• Give it slightly more light, away from cold windows, draughts and hot radiators.
• Raise the humidity to counter the dry air from central heating.

Diseases and pests

• Red spider mite: Fine pale speckles and webbing on the leaves, especially in dry air. Rinse the plant under the shower and raise the humidity.
• Mealybug: White, woolly tufts in the leaf axils. Remove them with a cotton bud dipped in a little alcohol.
• Yellow leaves: Usually overwatering or a spot that is too cold. Let the compost dry out a little between waterings.
• Brown leaf edges: Dry air or irregular watering. Raise the humidity and water more regularly.
• Long, bare stems: Too little light. Move it somewhere lighter and cut the stems back.

Through the year

• January: Less water, no feed. Light spot without draughts.
• March: Repot. Cut back long stems.
• April: Repot or prune. Resume feeding every 2 weeks. Take cuttings.
• May: Feed. Take cuttings. Add a moss pole if it is to climb.
• June: Feed. Trim stems to keep it compact.
• July: Feed. Watch for red spider mite in hot weather.
• August: Feed. Last pruning and cuttings.
• September: Last feed.
• October: Water less.
• December: Little water. Raise the humidity.

Edible and useful

Not edible. All parts of these houseplants of the arum family are poisonous: the sap is full of needle-shaped crystals (calcium oxalate) which, when chewed, at once cause burning pain and swelling of the lips, mouth and throat, with drooling and sometimes vomiting. Most at risk are cats, which like to chew trailing stems and leaves, dogs, and young children playing on the floor. Hang climbers and trailing plants out of their reach, clear up cut stems and cuttings straight away, and do not put a glass of cuttings in water where a cat drinks from it. Wear gloves when pruning and repotting, do not rub your eyes, and wash your hands afterwards. If your cat or dog drools or its mouth swells, call your vet. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Did you know?

• Young plants have arrow-shaped leaves. Once the plant starts to climb, the leaves become larger and deeply divided, so that it looks almost like a different plant.
• In warm regions such as Florida it has escaped from gardens and is regarded as an invasive plant in the wild.
• It belongs to the arum family, like the Swiss cheese plant, the philodendron and the dumb cane.