Banksia marginata

[markb]

This is a pruned B.marginata I just bought from a nursery. I think it will make a decent bonsai but I'm no expert. Any comments appreciated.
Cheers, Mark

[shibui]

banksia marginata is a widespread species. It seems there are many different types of this species. Some seem to do well as bonsai while I have had lots of problems with other forms.
Our local inland type has proved to be problematic for me so far. They persist for a few years but few have thrived and all eventually died. This may be due to my cultural practices or the variety itself.
More recently I have been growing a type grown from seed I collected in Tasmania. These ones are growing and responding to bonsai culture much better and I have some quite good smaller banksia bonsai from these and a few other coastal sourced plants.
Good luck with your banksia. Some things I have learned so far:
Root prune in the warmer months. for me that is November, December, January and February. In some places you may be able to go a month either side but banksias that I have root pruned in winter did not survive.
Root prune banksias annually while they are young and growing vigorously. They quickly fill the pot with masses of very fine roots that prevent water from penetrating and as a result the root ball gets the following summer drier despite adequate water. Banksia roots are brittle. I root prune by breaking off chunks of root mass by hand rather than using the root shears.
Banksias with proteoid roots can be killed by high doses of phosphate but banksias that are adequately fed will shed all proteoid roots and can be fed any fertiliser. If you are not sure stick to low P 'native' fertiliser but you will need to feed them in pot culture. Banksias die of starvation just like any other potted plant if they are not fed regularly.

[Rory]

I love banksia marginata.
Don’t cut back to a stumpy trunk. They’ll probably die. Always leave a lot of foliage on them. Don’t let the roots stay wet all the time. They are fairly good at allowing the soil to dry out, but don’t let them get bone dry.

Basically leave them alone in winter and allow them to grow vigorously without constant trimming throughout the year.
I would treat them similar to a leptospermum.

I completely agree with everything Neil says. I only trim and cut back to ramify it more in autumn and spring. I do heavy cut backs at the end of summer, but nothing in winter. I’ve heard they don’t grow fast in the lower, colder areas, but mine seems to grow quite strongly. This thread reminds me that I want to acquire another one soon.

[Borosta]

Great tips Neil and Rory. Just exactly what I was after for mine [THUMBS UP SIGN]


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[markb]

Thanks very much guys. I'm a newbie at this and looking forward to experimenting with natives.
By the way this plant was bought from Tasmanian Native Nursery in Hobart.

[shibui]

If mine are any indication that should make it ideal for bonsai.
Banksias thicken readily, even in pots, so you should get good thickening and growth just by feeding, watering and repot each year. They are also quite good at budding on older wood so you can allow them to grow tall and cut back fearlessly. Most of mine have also produced a trunk with good bends without much work from me but just keep an eye on it and prune if you see long straight growth forming.