Tree mallow

Tree mallow: how do you recognise it?

Habit

Loose, rounded shrub about 2 m tall and wide, with upright, fast-growing branches.

Foliage

Grey-green, softly hairy, lobed like a maple leaf.

Flower

Large, funnel-shaped flowers of 5–8 cm, pink or white with a dark eye, from June to October.

Colour

‘Barnsley’ is white with a pink eye and turns pink later; ‘Rosea’ is rich pink.

Lifespan

Short-lived: often only a few years, after which it turns woody and worn out.

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

Why grow it?

• Flowers non-stop from June to October, longer than almost any other shrub.
• Grows incredibly fast: a bare corner is filled in a single season.
• Bees and butterflies flock to the large flowers.
• Tolerates drought and poor sandy or chalky soil once established.
• Little work: one good prune a year in April is enough.

Tree mallow: where does it grow best?

• Full sun for the richest flowering; in half shade it flowers less and may lean over.
• Well-drained soil: sand, loam or clay, acid to chalky. Not cold, wet clay in winter.
• Dry to moderately moist: once established it copes with drought.
• Sheltered from strong wind: the fast, brittle branches can snap.
• Allow 1.5–2 m of space per plant.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Dry or normal

Size

2 m tall, 2 m wide

Hardiness

Hardy (to -15 °C)

Goes well with

• Lavender: Purple flowers and fragrance, in the same dry, sunny spot.
• Coneflower (Echinacea): Pink and purple flowers at the same time, for a harmonious, layered border.
• Sage (Salvia): Purple flower spikes at the front of the border, in the same dry sun.
• Butterfly bush (Buddleja): Even more flowers for bees and butterflies, flowering at the same time.
• Ornamental grasses: Fine plumes that form a soft edge around the large flowers.

Tree mallow: when and how to plant it?

Plant in April–May.

1. Plant in April or May, once the hardest frosts are over: it then has a whole season to root.
2. Dig a hole twice as wide as the root ball. Mixing in a little compost is enough.
3. Set the plant at the same depth as in its pot and firm the soil well.
4. Plant it at least 1.5 m from its neighbours.
5. Water in thoroughly straight away, then weekly in dry weather during the first year.
6. Spread a layer of compost or wood chip mulch around the base.

Care

Water

Weekly in dry weather in the first year. After that it copes, although it flowers more richly with an occasional good soak in a dry summer.

Feeding

In spring, compost or an organic fertiliser. Too much nitrogen gives soft shoots that freeze easily.

Mulching

After the April prune, a layer of compost or bark around the base protects against drought and frost.

Support

Usually not needed, but choose a sheltered spot: in autumn heavy branches can snap in the wind.

Renewal

After a few years it tires. Replace it in good time with a young plant from cuttings.

Tip: Cut all branches back to 30 cm in April: this keeps the shrub compact and flowering all summer. Take a few cuttings every year as a reserve, because it often lives only a few years.

Tree mallow: when to prune it?

Pruning months: April.

When: In April, when the new buds are visible and the hardest frosts are over.

How:

• Cut all branches back to about 30 cm above the ground, just above a healthy bud.
• Remove dead or frost-damaged branches completely.
• On white-pink selections such as ‘Barnsley’, branches with deep pink flowers may appear: cut them out at the base.
• After pruning, give compost and a layer of mulch.

Caution: Do not prune hard in autumn: the old branches protect the base from frost, and early pruning gives soft shoots that can freeze.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Softwood cuttings

In June–July: take 10 cm cuttings of non-flowering shoots, remove the lower leaves and root in moist cutting compost under plastic. They root easily, often within a few weeks.

Semi-ripe cuttings

In August–September: take 10–15 cm cuttings of firm, semi-ripe wood in sandy potting compost. Overwinter them frost-free and plant out in spring.

Tree mallow: how does it get through the winter?

Hardy to −15 °C: protect young plants.

• Hardy to about −15 °C: in hard Belgian winters it may be killed back to the ground and shoot again from the base in spring.
• Shelter it from cold wind and lay a layer of mulch around the base in autumn; protect young plants especially well.
• Only after winter, in April, cut back to healthy wood: then you can see what has frozen.

Diseases and pests

• Rust: Orange-brown spots on the undersides of the leaves, especially in damp summers. Cut off affected leaves and bin them, not the compost heap; leave space between plants.
• Snapping branches: The fast branches are brittle and can snap in wind. Choose a sheltered spot and prune back every year.
• Frost damage: In hard winters branches die or the plant is killed back to the ground. Wait until April and cut back to green wood.
• Short life: After a few years it turns woody and floppy. Take cuttings in good time as a reserve.

Through the year

• March: Do not prune yet: check for frost damage. Get mulch and compost ready.
• April: Plant or move. Cut all branches back to 30 cm. Give compost.
• May: Plant. First buds.
• June: Flowering begins.
• July: Full flower. Water in dry weather. Take softwood cuttings.
• August: In flower. Take semi-ripe cuttings.
• September: Flowering continues.
• October: Last flowers. Water in dry weather.
• November: Lay mulch around the base.
• December: Resting.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• It belongs to the mallow family (Malvaceae), like hollyhock, hibiscus and cotton.
• The well-known selection ‘Barnsley’ is named after Barnsley House in Gloucestershire, where it was found.
• After the April prune it reaches almost its full height again within a single season.