Althaea cannabina (Palm-leaf marsh mallow)

Botanical name

Althaea cannabina

Other names

Palm-leaf marsh mallow, Hemp-leaved hollyhock, Althaea armeniaca, Althaea kotschyi, Althaea narbonensis, Alcea cannabina, Hemp leaf mallow

Genus

Althaea Althaea

Species

A. cannabina - A. cannabina is an erect, woody-based, herbaceous perennial with open, branching stems bearing, deeply lobed, hairy, dark green leaves and clusters of small, cupped, lilac to deep pink flowers from summer into autumn.

Native to

Europe

Foliage

Deciduous

Habit

Erect

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Colour

Flower

Lilac, Dark-pink in Summer; Lilac, Dark-pink in Autumn

Foliage

Dark-green in Spring; Dark-green in Summer; Dark-green in Autumn

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How to care

Watch out for

Specific pests

Caterpillars , Flea beetles , Slugs

Diseases

Susceptible to a rust.

Specific diseases

Rust

General care

Pruning

Cut back after flowering.

Propagation

Sow in spring or autumn in a cold frame. Divide in sprin or autumn.

Propagation methods

Division, Seed

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Monthly care advice

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Where to grow

Althaea cannabina (Palm-leaf marsh mallow) will reach a height of 2m and a spread of 0.6m after 2 years.

Suggested uses

Wildlife, Wildflower, Prairie planting, Cottage/Informal, Beds and borders

Cultivation

Grows best in fertile, moist but well-drained soil in full sun but will tolerate a wide range of situations.

Soil type

Clay, Loamy, Sandy

Soil drainage

Moist but well-drained, Moisture-retentive

Soil pH

Acid, Alkaline, Neutral

Light

Full Sun

Aspect

South, West

Exposure

Exposed, Sheltered

UK hardiness Note: We are working to update our ratings. Thanks for your patience.

Hardy (H4)

USDA zones

Zone 9, Zone 8, Zone 7, Zone 6, Zone 5, Zone 4, Zone 3

Defra's Risk register #1

Plant name

Althaea cannabina (Palm-leaf marsh mallow)

Common pest name

Lance nematode; Nematode; Lance

Scientific pest name

Hoplolaimus spp.

Type

Nematode

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

2

Impact (1 is very low - 5 is very high)

4

General biosecurity comments

Nematode species potentially affecting a wide variety of crops; prohibition of soil likely to mitigate risk substantially; keep under review in light of interceptions or findings should they occur in the EU.

Defra's Risk register #2

Plant name

Althaea cannabina (Palm-leaf marsh mallow)

Common pest name

cotton mealybug

Scientific pest name

Phenacoccus solenopsis

Type

Insect

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

3

Impact (1 is very low - 5 is very high)

3

General biosecurity comments

Watching brief for potential impact on tomato production in the Mediterranean. Other southern European countries likely to be more at risk. Precautionary action will be taken on findings on planting material to protect glasshouse crops and botanical gardens.

Defra's Risk register #3

Plant name

Althaea cannabina (Palm-leaf marsh mallow)

Common pest name

Scientific pest name

Spilostethus hospes

Type

Insect

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

1

Impact (1 is very low - 5 is very high)

3

General biosecurity comments

Seed bug unlikely to pose a significant threat to UK plant health.

About this section

Our plants are under greater threat than ever before. There is increasing movement of plants and other material traded from an increasing variety of sources. This increases the chances of exotic pests arriving with imported goods and travellers, as well as by natural means. Shoot is working with Defra to help members to do their part in preventing the introduction and spread of invasive risks.

Traveling or importing plants? Please read "Don't risk it" advice here

Suspected outbreak? Click here for contact details to report to the relevant authority.

Date updated: 7^th March 2019 For more information visit: https://planthealthportal.defra.gov.uk/