Swamp She oak

Swamp She-oak (Casuarina obesa) is the tree to reach for when a site defeats everything else. It grows to about 9m tall and 5m wide, with a soft weeping crown of fine grey green needles, and it handles the two conditions most trees will not: salty soil and ground that stays wet. It is fast, frost hardy and wind firm: a serious windbreak tree rather than an ornamental one.

Why you'll love it

• It grows in salt and waterlogging. Saline flats, dam edges and low lying paddocks that drown other trees suit it, and it takes long dry spells once established.
• A real windbreak. The fine drooping foliage filters wind instead of blocking it, so you get shelter rather than turbulence behind a solid wall.
• Fast to useful height. Growth is quick in the first few years, so shelter and shade arrive within a handful of seasons.
• Native and full of birds. Small honeyeaters and finches shelter in the dense weeping habit, and black cockatoos feed on the cones.

Where it works best

Windbreaks and shelter belts. Plant 3m apart in a row, or in a double staggered row at the same spacing on an exposed boundary. That gap lets each tree fill out without the row thinning at the base.

Wet and saline ground. Dam surrounds, drainage lines and salt affected paddocks are where it earns its keep. Few trees this size will tolerate periodic inundation.

Coastal gardens and shade. Salt laden wind does not mark it, and a single tree gives light dappled shade over a lawn or driveway.

Growing swamp she-oak in Australia

Position and climate. Full sun. It suits subtropical, warm temperate, cool temperate, Mediterranean and arid gardens, which covers most of the country outside the wet tropics. Frost is no concern.

Soil. Almost anything. Sand, clay, saline ground and soil that holds water after rain are all fine. Rich soil is not required, and heavy feeding does more harm than good.

Water and feed. Water weekly through the first two summers to get the roots down, then leave it alone. Native fertiliser once in early spring is plenty, since she-oaks fix their own nitrogen through root nodules.

Pruning. Little is needed for a shelter belt. For a shade tree, lift the lower branches early to give clearance under the canopy. Expect a steady drop of fine needles, which forms a soft mulch but discourages lawn directly underneath.

What to expect when it arrives

It is currently grown in a single size, an advanced 90L tree, and that size runs on backorder, so allow time before dispatch. What arrives is a substantial tree with a formed trunk and crown, not a tube, so it makes an immediate difference on an exposed site.

Stake advanced stock for its first year and water deeply rather than often. Delivered Australia wide, with delivery from $29.95. Advanced and large stock is freighted at cost, and every plant is covered by our 30 day healthy plant guarantee.

Plant care guides and related reading

• Read about planting in waterlogged ground.
• Compare other windbreak and shelter plants.
• Browse the wider Australian native tree range.
• See more salt tolerant plants for exposed sites.

Common questions

How far apart do I plant a shelter belt?

Three metres apart along the row. On a very exposed boundary, run two staggered rows 3m apart, which filters wind more effectively than a single dense line.

Will it survive a paddock that floods?

Yes, this is the tree's strong suit. It tolerates periodic inundation and saline soil, though the crown still wants sun and it will not thrive in permanent deep water.

How close can I plant it to a house or pipes?

Give it 8m to 10m. It is a fast growing tree with a vigorous root system built to seek water, so keep it away from drains, septic lines and slabs.