Cousin It She-oak, Prostrate Swamp Oak, Groundcover Sheoak, Grey Oak
Casuarina glauca 'Cousin It'
The Story
Plant Bio
Casuarina glauca, commonly known as the swamp oak, is an evergreen Australian tree native to brackish coastal estuaries and riverbanks along the eastern seaboard. The species features slender, segmented branchlets that function as leaves and produces small woody cones on female trees.
'Cousin It' is a prostrate, mounding clonal selection that forms a dense, cascading mat of blue-green foliage over ground and retaining walls. This cultivar is entirely sterile and non-flowering, relying on its tight, hair-like structural form rather than seasonal blooms.
Uses & Benefits:
Essentials
At a Glance
Plant Type
Groundcover
Height
12 inches
Width
79 inches
Light
Full Sun, Partial Sun
Zones
9, 10
Water
Low
Humidity
Moderate
Lifespan
Long-lived
Native To
Australia
Toxicity
Non-toxic
Planting
How to Grow
- Select a planting site in full sun to partial shade with adaptable soil ranging from sand to heavy clay.
- Dig a hole twice the width of the root ball and plant at the same depth as the nursery pot.
- Water deeply and regularly during the first year to establish a deep, resilient root system.
- Apply a low-phosphorus native slow-release fertiliser in spring if growing in highly depleted soils.
- Mulch around the base to suppress weeds while the slow-growing stems establish their ground-hugging matrix.
Pro Tip
Prune only the active green tips to control spread; cutting back into old, leafless grey-brown wood prevents regrowth as the plant cannot regenerate from bare timber.
Keep It Thriving
Care Guide
Do
- Water regularly during the first twelve months to ensure deep root establishment.
- Allow the plant to cascade naturally over rocks, banks, or retaining walls.
- Use a low-phosphorus native fertiliser if feeding is required.
Don't
- Do not prune back into old, bare, leafless wood.
- Do not over-fertilise with standard high-phosphorus garden fertilisers.
- Do not expect rapid lateral spread during the first year of establishment.
Seasonal Care Calendar
| Task | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fertilize | ||||||||||||
| Mulch | ||||||||||||
| Pest Check | ||||||||||||
| Plant | ||||||||||||
| Prune |
Watch Out For
Pests & Diseases
Common Pests
Common Diseases
In the Garden
Landscape Uses & Companions
Landscape Uses
Multiply
Propagation Methods
Good to Know
Common Questions
Cousin It She-oak, Prostrate Swamp Oak, Groundcover Sheoak, Grey Oak questions
What zones can Cousin It She-oak, Prostrate Swamp Oak, Groundcover Sheoak, Grey Oak grow in?
Cousin It She-oak, Prostrate Swamp Oak, Groundcover Sheoak, Grey Oak is hardy in USDA Zones 9–10. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.
Does Cousin It She-oak, Prostrate Swamp Oak, Groundcover Sheoak, Grey Oak need full sun?
Cousin It She-oak, Prostrate Swamp Oak, Groundcover Sheoak, Grey Oak does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.
Is Cousin It She-oak, Prostrate Swamp Oak, Groundcover Sheoak, Grey Oak drought tolerant?
Yes — once established (usually after the first full season), Cousin It She-oak, Prostrate Swamp Oak, Groundcover Sheoak, Grey Oak handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.
More Casuarina to compare
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Grow Cousin It She-oak, Prostrate Swamp Oak, Groundcover Sheoak, Grey Oak with confidence
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