Giant Timber Bamboo Bambusa oldhamii

Giant Timber Bamboo is the big clumping bamboo for a big job: a tall, dense wall of thick, straight green culms that rises above the roofline of a two storey house and blocks a view the way a row of trees would, in a fraction of the width. Bambusa oldhamii is upright rather than arching, with the culms standing close together in the clump and the foliage held mostly in the upper half. It is also one of the hardier Bambusa species, coming through frosts that knock tropical bamboos to the ground.

Size is the whole point and the whole problem. This is not a plant for a small backyard or a side passage. A mature clump is broad at the base and heavy at the top, it sheds leaves and old culm sheaths all year, and it throws a lot of shade, so give it a boundary with space around it and think about whose garden it will darken.

Each culm is as tall as it will ever be

A bamboo culm puts on all of its height in one season, in a matter of weeks, and then stops for good. What changes over the years is the clump: a young plant sends up thin culms, and every summer's crop is heavier, up to whatever the site can support. That makes the grade you plant matter more with bamboo than with most things. A small pot means a few seasons of slender canes, while a large one, such as the biggest grades in Super Advanced Trees 200L and Over, starts with a clump already throwing heavy culms and screens far sooner. Our guide Planting an advanced tree covers getting a big rootball settled in.

New shoots appear through summer and into autumn once the soil is warm and moist, and with the wet season in the tropics. They are soft and easily snapped by dogs, mowers or a careless boot, so mark the area while they are coming up. They are also edible and well regarded, but bamboo shoots must be peeled and boiled before eating, because raw shoots contain compounds that release cyanide.

Clearance, wind and water

Full sun gives the tallest, densest growth. Plant it in deep soil that drains, with room to widen, keeping the clump several metres from the house, well away from sewer and stormwater lines, and back from paving, which a mature clump of this weight will lift. It does not run the way Phyllostachys and the other running bamboos do, so no barrier is needed to stop it spreading, but its root mass is dense, wide and very hard to dig out once established. In wind the tall culms sway and rub on gutters, fences and roof edges, so allow for movement at the top as well as width at the base.

Keep the soil moist from the first sign of shoots until they stop extending: a dry spell in those weeks is the usual reason for a thin crop of small culms. A clump this size puts on a great deal of growth each summer, so feed it generously, with a heavy dressing of pelletised poultry manure in spring and a second in midsummer as the shoots begin.

Where oldhamii sits among the clumpers

Pick oldhamii when the brief is height, bulk and a screen that hides a tall building. If the stems themselves are meant to be the feature, China Gold Bamboo has yellow culms with green stripes on a less massive plant. Oldhamii culms are thick and woody, so thinning is saw work: each winter, cut a few of the oldest at the base, and keep the straight canes that come out for stakes and frames.

Choosing a size

This plant is available in 5 sizes, from 300mm up to 200L, priced from $159.00 to $869.00 per plant. The size shown is the pot the plant arrives in, which is the rootball, not the height of the plant. Every size here is established stock rather than a starter plant, so this line is intended for immediate effect rather than for growing on. Not sure which to choose? Read our guide to fast growing screening plants.