If you are using water to propagate your stem, change it at least every other.
Feb 18, Prune to improve the shape, allow clearance, and create the type of landscape that works best in the garden. Bottlebrush plants have a tendency to send up suckers, so it is necessary to trim those back at regular intervals. The bottlebrush is also propagated from cuttings, so careful pruning is necessary to create starts for new bottlebrush plants.
For shape, prune it in the spring before it begins to put out flower buds.
Mar 01, The correct way to deal with this bush is to tip prune about 1/3rd only of the shrub immediately after flowering leaving the rest to itself tip prune, which as it says just prune off the tips, which is where the spent flower is you should not prune it more vigorously unless it's getting in your way, and you should leave on those nutty bits until they fall off themselves, which can take some years.
Dec 03, Bottle brush trees require little pruning if you like the natural shape; prune in summer after it flowers to keep it shorter or more tree-like.

Prune the New Wood The Australian Natural Botanic. Sep 28, Start by digging your planting hole at least two to three times as wide and no deeper than the rootball of your Bottlebrush plant.
Regular pruning will help keep your bottlebrush at an ideal height and shape for your garden.
The wider the hole the better. Place native soil removed from planting hole around the perimeter of the hole, in a wheel barrow, or on a tarp. Step 2. Jun 07, The time of the year you choose to pruning the bottlebrush tree will directly impact the growth and blooming; continuous pruning leads to a lack of flowers in the preceding year.
You should remove the inner branches if they are damaged or diseased, whereas thin them lightly if the interior growth is turning brown due to lack of sunlight.