Clasping Venus looking glass.

At a glance

Care level

Easy

Plant type

Annual wildflower

Light

Full sun to partial shade

Indoor light

Direct sun

Water

Every 3 to 7 days

Mature size

2 feet

Growth rate

Fast

Hardiness

USDA 4 to 9

Bloom time

Late spring to mid summer

Care

Keep the soil consistently moist while the plant is establishing itself. Watch for wilting during dry spells, as this plant prefers a steady supply of water. Deadhead spent flowers if you want to encourage a longer blooming period.

Watering

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

Feeding

A light application of balanced fertilizer once during the growing season is plenty.

Pruning

Trim back dead stems after the plant finishes flowering to keep the area tidy.

Repotting

Since this is an annual, you will typically replace it each season rather than repotting.

Soil

Well draining sandy or loamy soil

Soil pH

6.0 to 7.5

Temperature

-34 to 35°C

Humidity

30 to 70%

Drought tolerance

Moderate

Lifespan

Annual, typically 1 year

Deer and rabbits

Moderate

Safety

People

There are no reports of significant toxicity, but it is not considered an edible plant.

Children

Keep away from small children as the plant is not food and may cause mild irritation if ingested.

Contact allergens

None known.

Airborne allergens

Pollen may cause mild reactions in sensitive individuals.

Edibility

This plant is not typically consumed and should be avoided as food.

How to identify it

• Heart shaped leaves clasping the stem
• Violet flowers with five petals
• Erect stems reaching up to two feet
• Small capsules containing tiny seeds

Height

0.15 to 0.6m

Spread

0.1 to 0.2m

Leaves

green, deciduous

Flowers

violet, blue, 1 to 2cm

Fruit

brown, Late summer

Problems to watch for

• Powdery mildew · White fungal growth on leaves during humid periods.

Growing it

Propagation

seed

When to plant

spring, autumn

Overwintering

As a winter annual, it survives the winter as a small rosette of leaves. No special protection is needed.

In containers

It is not well suited for containers due to its short life cycle and preference for open ground.

Plant in groups to create a drift of color that mimics a natural meadow.

Grows well with

• Blue-eyed Grass · They share similar light and moisture requirements in meadow settings.
• Wild Strawberry · This groundcover provides a nice contrast to the upright stems of the looking glass.

Similar species

• Small Venus' looking-glass · It is very similar but typically has smaller, less showy flowers.

Science

Family

Campanulaceae

Genus

Triodanis

Order

Asterales

Class

Magnoliopsida

Native range

Most of North America.

Conservation

It is widespread and common throughout its range.

It thrives in disturbed soils and open woodlands where it can quickly colonize bare ground.

Value to wildlife

nectar source

Pollinators

bees, butterflies

Uses

wildflower meadows, pollinator gardens, naturalized areas

Taxonomy resolved against GBIF.

Questions people ask

Is it a weed?

It is often considered a native wildflower, though it can appear in lawns or disturbed soil.

Does it need full sun?

It prefers full sun to light shade.

Where the name comes from

The genus name Triodanis comes from Greek for three teeth, referring to the calyx lobes, while perfoliata describes the leaves that seem to be pierced by the stem.

Good to know

• It is commonly called Venus looking glass because of its reflective, shiny appearance in some light.
• The leaves appear to be pierced by the stem, which is why it is called perfoliata.
• It is a winter annual that germinates in the fall and grows slowly through the winter.