Southern running-cedar.

At a glance

Care level

Difficult

Plant type

Lycopodiophyte

Light

Partial shade to full shade

Indoor light

Bright indirect

Water

Every 3 to 7 days

Mature size

4 to 8 inches tall

Growth rate

Slow

Hardiness

USDA 3 to 7

Care

Keep the soil consistently moist and mimic a woodland floor with high humidity. Watch for browning tips which often signal the air is too dry or the soil has dried out. It is quite sensitive to transplanting and prefers to be left undisturbed in its preferred spot.

Watering

Keep the soil evenly damp but never soggy to prevent root rot.

Feeding

Use a very dilute, balanced liquid fertilizer only during the active growing season.

Pruning

Only trim away dead or damaged stems to maintain the plant's health.

Repotting

Repot sparingly as this plant dislikes root disturbance and prefers to stay in its established container.

Soil

Acidic, sandy, or peaty soil

Soil pH

4.5 to 6.0

Temperature

-40 to 25°C

Humidity

60 to 90%

Drought tolerance

Low

Lifespan

Perennial, long-lived in stable forest environments.

Deer and rabbits

High

Safety

People

The plant is considered toxic if ingested due to the presence of various alkaloids.

Children

Keep away from small children as the foliage is not for consumption and may cause illness if chewed.

Contact allergens

The spores can cause mild skin irritation in sensitive individuals.

Airborne allergens

The fine spores released in late summer may cause respiratory irritation if inhaled in large quantities.

Edibility

This plant is not edible and contains alkaloids that can cause digestive distress.

How to identify it

• Fan shaped, flat branchlets
• Deep green, scale like leaves
• Spreads via underground rhizomes
• Horizontal, creeping growth habit

Height

0.1 to 0.2m

Spread

0.3 to 1m

Leaves

green, evergreen

Flowers

0cm

Problems to watch for

• Root rot · Occurs when the soil remains waterlogged for too long.

Growing it

Propagation

division, spores

When to plant

spring, autumn

Overwintering

It is fully hardy and stays green through the winter, so no special protection is needed.

In containers

It does not grow well in containers due to its specific need for symbiotic soil fungi.

Plant alongside other acid-loving woodland species that appreciate consistent moisture and dappled shade.

Grows well with

• Eastern Hemlock · They naturally share the same cool, acidic woodland habitat.
• Wintergreen · Both plants enjoy the same acidic, shaded forest floor conditions.

Similar species

• Running Pine · It has a similar growth habit but with distinct blue-green foliage.

Science

Family

Lycopodiaceae

Genus

Diphasiastrum

Order

Lycopodiales

Class

Lycopodiopsida

Native range

Eastern North America.

Conservation

It is protected in several states due to over-collection for holiday wreaths and is considered vulnerable in parts of its range.

It thrives in acidic, well-draining forest soils where it forms dense, carpet-like colonies.

Value to wildlife

provides ground cover for small forest creatures

Uses

ground cover, woodland garden accent

Taxonomy resolved against GBIF.

Questions people ask

Can I grow this in a regular garden bed?

It is very difficult to establish in home gardens because it requires specific soil fungi to thrive.

Does it need full sun?

No, it prefers partial to full shade and cool, moist conditions.

Where the name comes from

The genus name Diphasiastrum comes from Greek words meaning double-appearing, referring to its branching patterns, while digitatum refers to the finger-like arrangement of its branchlets.

Good to know

• It is often called ground cedar because its foliage looks like tiny cedar branches.
• It spreads via long, creeping underground stems called rhizomes.
• It does not produce flowers or seeds, but reproduces through spores.
• It was historically used to make flash powder for early photography because its spores are highly flammable.

Also in

• Plants for shade
• Deer-resistant plants