Banksias
By Craig Wilson
Gentiana Nursery
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There are 173 Banksia species in Australia. Banksia falls into the Ficus range. They are not interested in growing flowers as they are too big for bonsai plant. Style tends to be formal and sloping and can grow cascade style.
There are a variety of Banksias, including:
Integrafolia, Serrata, Marginata, Ericafolia, Spinulosa and Admuluri.
The Integrafolia variety are not so good in ground.
The Serrata variety are hardy to grow in ground and the foliage doesn’t tend to suit flat pad foliage style as readily (however it can be done).
Tips for growing Banksias as a bonsai
Better to start with young sapling rather than old nursery stock.
Start by chopping off roots and plant on a sloping angle. Good result in 7-8 years.
Develop curve right at base of tree.
Scars tend to roll over and are not visible when working with sacrifice branches.
Banksia tend to back bud really successfully. Cut back hard and they will bud. Keep short and develop thick trunk.
Keep watch on branches that tend to shoot off in wrong direction (natives tend to do that).
Fertilise with phosphorus and they get used to it. eg. Seasol + Powerfeed
Banksias are hungry. Feed every 4-5 days.
No diatamite any more. Leads to clay effect.
Using pumice from Damien at North West. Manmade pumice (NSW) via John Hayman.
Annual repot in Dec/Jan Summer.
Cut off in December and defoliate in early Spring.
Try to develop lots of twigs = lots of fine growth and smaller leaves.
To get ramification pinch out new tips, fertilise. Helps to develop bushier, denser foliage.
Break leaves in half by finger rather than remove leaves. Allows for photosynthesis.
In Summer, lots of half leaves on trees. Feed, feed, feed. Will rebud next season.
Later in season, after doing the half leaving, remove half leaves. Deciduous trees will drop those leaves.
Keep banksia low and at workable height. Banksia will shoot successfully.
Seal any big cuts. Apply thinly as if too thick, it will slow the callous process. Use putty.
Look at where trunk line is looking to be and keep that area open for light and sunshine impact.
Sacrifice Branches
Any side-branch on your tree can be used as sacrifice branch. When selecting which branch you want to grow out, keep in mind that you will create a branch that is very thick: After removing this branch, a scar will remain. For several years you will need to work on closing the wound in the bark. So ideally you pick a branch in a spot on the back of the tree, or in the bend of the trunk. Wire this branch sideways a little, so that there is a straight angle between the branch and the trunk.
This will do two things: The attachment to the trunk will be as small as possible later on, and the branch will move away from the trunk as quick as possible.
As the branch grows, it will add girth to the trunk below the attachment point. Everything above the branch will not get thicker as a result of the sacrifice branch. Therefor this is an ideal way to increase taper: Select a branch halfway up the trunk, and you will thicken the lower half, leaving the upper half alone. Also, it may be used to correct inverse taper problems: by letting sacrifice branches grow out at strategic spots, local areas may be assisted in getting thicker
Cut cut cut! Strong backbudding. Spread out branches, not clustered around on3 spot.
With banksia tube, cut off the stem. Root prune. Plant at angle. Move into larger pots slowly. Too soon and they get too wet.