Yar (highland casuarina)
Casuarina oligodon
Planted in fallow gardens across the New Guinea highlands for centuries: it fixes nitrogen, rebuilds tired soil and gives firewood and fence posts.
Hardiness: zones 10 to 12
Light: full sun
Size: about 60 ft tall, 20 ft wide
From: New Guinea highlands
Here: Too tender to overwinter outdoors on the Lake Erie shore (zone 6b to 7a): grow it in a pot and bring it in, or treat it as an annual.
Good for: fixing nitrogen in the soil, screens and hedges, wildlife.
Native to: New Guinea & Melanesia. Hardy in zones 10 to 12.
The story
Highland farmers in Papua New Guinea have planted yar in their resting gardens for at least a thousand years, one of the oldest tree-fallow systems known. The trees fix nitrogen, drop a thick mulch of needles and bring worn-out sweet potato ground back to life in ten or fifteen years, while giving firewood and timber.
Planting
Full sun in most soils, including poor and wet ones, in a frost-free climate. Plant seedlings at the start of the rains, a few metres apart, in ground you want to rest.
Growing
Fast and undemanding. Thin the stand as it grows and use the thinnings as poles. Leave the fallen needles as mulch.
Harvest and use
Not a food plant. Harvest poles and firewood from thinnings; clear and replant the garden when the soil has recovered.
What to watch for
Shallow roots compete with crops planted too close. Grow it only in tropical highlands where it belongs; some casuarinas are invasive elsewhere.
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More helper plants for soil, wildlife and biomass
General guidance, not professional advice. Conditions vary by yard and year; for local specifics ask your county extension office. Never eat a wild plant you cannot identify with certainty. Traditional uses are shared as history, not medical advice. © 2026 Sean Priest · Irie Orchard. Terms & credits · Privacy · Home