Herb Robert.

At a glance

Care level

Easy

Plant type

Herbaceous annual or biennial

Light

Partial shade to full sun

Indoor light

Bright indirect

Water

Every 3 to 7 days

Mature size

12 to 18 inches

Growth rate

Fast

Hardiness

USDA 4 to 9

Bloom time

Late spring to early autumn

Care

Keep the soil consistently moist but not waterlogged to mimic its natural woodland habitat. Watch for wilting if the soil dries out too much, as this plant prefers steady hydration. It is quite adaptable, but it does best when it has a bit of protection from harsh afternoon sun.

Watering

Water whenever the top inch of soil feels dry to the touch.

Feeding

Apply a balanced liquid fertilizer sparingly during the active growing season.

Pruning

Trim back spent flower stems to encourage a tidy appearance and prevent excessive self seeding.

Repotting

Repot only if the plant becomes root bound or if you need to refresh the soil.

Soil

Well draining, humus rich soil

Soil pH

Neutral to slightly alkaline

Temperature

-20 to 30°C

Humidity

40 to 70%

Safety

People

The plant is generally considered non-toxic but may cause mild skin irritation in sensitive individuals.

Children

Keep away from small children as the foliage can be irritating if handled excessively or ingested.

Contact allergens

The glandular hairs on the stems and leaves can cause contact dermatitis in sensitive people.

Airborne allergens

Pollen may cause mild reactions in those with severe seasonal allergies.

Edibility

While historically used in herbal medicine, it is not recommended for consumption due to potential toxicity and lack of modern safety data.

How to identify it

• Lacy, fern like foliage
• Small five petaled pink flowers
• Stems often turn reddish
• Distinctive musky scent when crushed

Height

0.1 to 0.5m

Spread

0.15 to 0.4m

Leaves

green, reddish-bronze, deciduous

Flowers

pink, magenta, 1 to 2cm

Fruit

brown, Summer to autumn

Problems to watch for

• AphidsCommon
• Powdery MildewCommon
• Slugs and SnailsCommon
• RustUncommon

Growing it

Propagation

seed

When to plant

spring, autumn

Plant it in areas where you want a naturalizing ground cover, but be prepared to pull seedlings if they spread too far.

Grows well with

• Foxglove · They share similar woodland habitat requirements and bloom times.
• Ferns · Ferns provide the dappled shade and moisture that this geranium prefers.

Similar species

• Dove's Foot Cranesbill · It is a similar small-flowered annual geranium often found in similar habitats.

Science

Family

Geraniaceae

Genus

Geranium

Order

Geraniales

Class

Magnoliopsida

Native range

Europe, Asia, and parts of North Africa.

Conservation

It is a common and widespread plant not currently of conservation concern.

It grows in moist, shaded environments like woodland floors and rocky crevices where it can easily colonize disturbed soil.

Value to wildlife

nectar source

Pollinators

bees, butterflies, moths

Uses

ground cover, woodland gardens, pollinator gardens

Taxonomy resolved against GBIF.

Questions people ask

Is Herb Robert a weed?

It is often considered a weed because it spreads quickly by seed, though many gardeners appreciate its delicate flowers.

Does it grow in shade?

Yes, it thrives in partial to full shade, making it perfect for woodland areas.

Where the name comes from

The scientific name honors Saint Robert, who was thought to have used the plant to cure various ailments. The common name Herb Robert is a direct derivation of this association.

Good to know

• The leaves often turn a brilliant red color in the autumn or when exposed to full sun.
• It is an annual or biennial plant that readily self-seeds in the garden.
• The seeds are ejected explosively from the fruit capsule to spread away from the parent plant.