The banksia workshop

[squizzy]

Loving this thread! Banksia's are my favorite Aussie native so will be watching closely

One other quick note on repotting. All my banksia sulk for a while ( some a long time) after repotting. I see they are over it when I start to notice those little pink bursts of growth appearing.

I find much the same ... with big differences in duration depending on the average temp when it's done.

Quickest recovery/new growth I've seen was a week or so later on a couple of smaller tree's (1 ea serrata & integrifolia) I repotted early Jan this year (>40 degree days), post repot they got morning sun till about midday, then filtered as they were shaded by the neighbors Jacaranda. Water twice daily until I saw regrowth (so they stayed quite damp), then back to standard once a day via the irrigation dripper

Slowest was a couple of serrata's that were repotted in May/June last year ... probably saw no action at all until late Aug/early Sep and even now they have not regrown to the level of my other Banksia's. These were in full sun straight after the repot due to cooler weather & watered by the irrigation only (probably every other day). These weren't the healthiest tree's to start with though - found in the back of a community nursery, having been forgotten about for a couple of years

I also repotted a couple (1 ea serrata & integrifolia) in Oct last year, they probably did nothing for about 4 weeks

I'm now trying to stick to mid summer for reporting of Banksia's

The one I've had no success with is ericifolia. Tried a couple of these (inspired by PeterH's amazing tree ) but all have dropped dead after the first trunk chop. These were larger ones (200 & 300mm nursery pots) from a regular (native) nursery and chopped back to ~40cm tall with a couple of small branches only remaining ... maybe to hard, too fast? I dunno


Has anyone tried root grafting on an integrifolia? I have one that only has roots on one side, so I'm hoping to try to improve the nebari next summer ... any tips appreciated (never tried root grafting on anything before)

Hi mike.

Great contribution. I’m interested to hear from Grant as to why his don’t sulk after repotting. Maybe he does something different to you and I. It might be down to the plants reserved energy prior to repotting?
Re you root graft question. I haven’t tried but if it’s anything like my approach graft experience it will take a while. Have you considered ground layering?

Squizzy

[shibui]

I have had similar results to MikeK. Banksias repotted in warmer months just keep growing, even if they have actively growing new shoots. Even repotting and root pruning does not seem to worry them. Plants repotted in March sulked until the following December then gradually recovered but were probably set back one full growing season as a result.
A couple died after winter root pruning so I haven't tried that again. There's plenty of time over summer to repot banksias when they respond better.

I have reduced roots of young banksias drastically. Up to 80% of roots removed with no obvious ill effects. I usually take off around 1/2 of the fine roots at each repotting.

Elsewhere I have documented that Banksias rapidly fill a pot with very fine roots viewtopic.php?f=69&t=26556&p=262536&hil ... ui#p262536. Eventually watering becomes a major issue and I believe that a lot of potted banksia deaths in spring and summer could be attributed to dehydration due to excessive root growth. I now try to repot most of my developing banksias annually which seems to alleviate this problem for me. Trees in bonsai pots have been able to go several years between repot.

[Starfox]

If you have accidentally forgot about giving strong liquid fertilizer, my suggestion is to simply flush the pot with a hose for a long time in an effort to dilute the effect as much as possible.
Then slowly start at a later date with low dosage.

It was a case of this and the leaves went all pale and crispy on two of them, one I gave a real good soaking too and the other I repotted with fresh soil and gave a good flushing too. Not sure if they are past the point of no return or not although there is green using a scratch test. Hopefully they bounce back, I guess I can report back on if they do or don't.

[Grant Bowie]

Some Good observations about repotting so far, but I will lay out my methods.

I repot in Canberra once it warms up , so November or so. On the coast I would do it a month or two earlier; September or preferably October; once again it must have warmed up and stay warm.

If you repot too early and take off too much root then the tree will sit in wet, cold potting mix and sulk. Simples.

If you miss the optimum time for repotting then leave it for the following year if you are unsure. Otherwise a light repot in late summer would be another alternative but it must be warm with a good growth period to follow. Root bound trees never die of root rot, so if you keep the tree healthy (consistent fertiliser regime )then you should have no problems if you miss out on a repot.

Fertilising is often down to personal choice, lifestyle etc.
Currently ( and for many years now) I use powerfeed at the recommended normal rate (read the label) every 2 weeks through the growing season, and a small amount of standard Osmocote( not native Osmocote) in the potting mix at repot time. Banksia rarely recover if you over fertilise or fertilise inappropriately . Start low and build up the fertilising over time.

Hope this helps,

Grant

[Rory]

Some Good observations about repotting so far, but I will lay out my methods.

Also to re-iterate what Grant advised to me so many years ago 'Don't over-pot Banksia'. (Don't put too much potting mix than is required in the container)

This goes for most trees (great thread from Mike about this), but in particular, species that are prone to root-rot are most susceptible from over-potting.

[Boics]

Hi all, I've just updated a thread I've been running for Banksia Serrata.
I think it's both a decent reference and inspiration for what can be achieved in a relatively short period with this species.
The biggest thing I'll say is that the tiny fibrous roots will fulfill a pot relatively quickly (1-2 years) and a re-pot is essential or both vigour and likely a tree will be lost!
I also have a Coastal Banksia which is still more a work in progress but I've treated this identically to my Serrata - with good results.

https://www.ausbonsai.com.au/forum/view ... 53&t=19570

And one pic here for good measure:

[Rory]

Has anyone successfully grown Banksia tricuspis as bonsai?
They seem very nice.

On a side note, I noticed on the CBS site, it shows a Banksia spinulosa ‘birthday candles’, with really thin and small candles and the caption reads the candles grow in proportion to the tree?
Seriously? Gosh. Are there many others that do as well?

All the ‘birthday candle’ banksia flowers I’ve seen are really fat, albeit shorter than regular species’ candles, regardless of the size of the height of the tree/bush.

[hard1all]

Thanks for this post. Have just got my first banksia so have learned from this post - "heaps".
I'd be grateful for any and all advice on Banksia ericifolia - especially fertilising.
Yes, I have carefully noted Grant Bowie's earlier comments on the subject with gratitude.
Thanks.

[Rory]

Thanks for this post. Have just got my first banksia so have learned from this post - "heaps".
I'd be grateful for any and all advice on Banksia ericifolia - especially fertilising.
Yes, I have carefully noted Grant Bowie's earlier comments on the subject with gratitude.
Thanks.

A beautiful tree.

I have never used liquid fertilizer on my B. ericifolia.
I just use Osmocote slow release native fertilizer. Honestly it flourishes with it and there is no need for liquid in my opinion.
I don't see the advantage of using liquid fertilizer for Banksia.
I've often had problems with liquid fertilizer, and killed many Banksia over the years.

They love full sun, and I've often let B. erificolia get very dry , but the ends will droop to tell you it needs watering. But if you give it a good flush of water, within 1 hour it will be back to full health.
Make sure you have very good drainage though.
The growth slows down a fair bit in shade, so best to keep in full sun if you can.

I've root pruned them very heavily and never had problems with them. I find them to be quite hardy.
I have not cut back on very old wood as mine are only a few years old, but on younger material they easily back bud from trunk chops.

All Banksia thrive with a good mix of washed river sand for improving drainage. But if you get full sun, don't use a lot of sand as it will drain too fast and dry out the mix too quickly on a hot and windy day. I usually start low with the river sand and add more if you need it over future repots if the mix is not draining fast enough.

And lastly, with Banksia... don't leave the repotting too long if its thriving. The roots harden quickly and you'll end up having to cut back heavily as they wont be easily separated. Banksia roots harden very quickly, but on the plus side you can often cut back the roots very hard and not affect the health of the tree. I don't reduce foliage anymore after heavy root removals. Its amazing how little root Banksia need to keep a higher percentage of foliage healthy.

[shibui]

I have not grown many B. ericifolias here, mostly stick to B. serrata and B. integrifolia as they seem to grow faster and respond better.
Fertilizer: Don't fall into the trap of not fertilizing because you are frightened of all the hype and possible consequences. Banksias in pots die from starvation just like most other plants. It is the proteoid roots that cause any problems but banksias don't always have proteoid roots. They grow these as a response to poor conditions and lack of nutrients. A well fertilized banksia will have few if any proteoid roots and can be fertilized with any normal fertilizer.
If in doubt as to the roots start with lighter doses of fert and build up to full strength over a couple of months. Proteoid roots are mostly around the edges of the pots so nearly all are removed at repotting so that is a good time to transition to full strength fertilizer.
Mine get powerfeed liquid at full strength. I also add some chook poo pellets to the top of the pot every month or so over summer and once in winter. Other trees get Thrive liquid but I am still cautious about the P levels in that so don't use it on the banksias except occasionally by mistake.

In the early days I lost a lot of banksias to starvation. I also lost quite a few to sudden death in spring and early summer. After some autopsies I found all those trees were really root bound and discovered that banksia roots are really fine and matted and tend to repel water. I believe that most of those deaths were from dehydration. Even though I was watering normally the water could not penetrate the root mass and the trees got slowly drier and drier until they died. It seems banksia roots grow really quickly and young trees will fill a pot in a single year. The solution is to repot more often. As Rory has noted above, even hard root prune will not adversely affect the tree. i try to repot younger growing banksias every spring/summer to make sure they have sufficient space in the pot to survive the summer.
At repotting it can be hard to cut through the matted root mass with root shears. I tend to just grab a handful and tear off chunks. The roots are mostly very fine and quite brittle? and it is quite easy to do this by hand.

[Rory]

At repotting it can be hard to cut through the matted root mass with root shears. I tend to just grab a handful and tear off chunks.

I learned from the same school that Neil teaches in.

I recall the worst one I ever attempted was a very, very pot bound Banksia integrifolia 'sentinel'. The root mass was concrete. It was so tight I couldn't even pry it apart or rip it with my hands. I reduced as much as I could with cutters, but in the end it died. It was just too compact and couldn't be watered properly. Even though it was soaked heavily each time at watering it looked like it had gone 10 years without a repot.

When I see a great aged Banksia material for sale, I'll often pull off the pot and if the root system could deflect a nuclear warhead, I gently put it back and use the money on a case of lager instead.

[PWC]

I have over a dozen that are one year old that I grew from seed. some are in pots and some in the ground. What would be the best approach for the development of the roots? The ones in pots in most cases are more advanced than the ground grown, they have performed beyond my expectation a couple are already around 30 cm in height.

I believe its best to do root work in warmer weather, so down here that would be November or December.

[shibui]

November, December or even into January seem to be good times for root work. Mine don't develop many thick roots, just masses of fine ones. I just keep hacking off sections to make room for more to grow. There will be some thicker roots close to the trunk so use the usual techniques to remove or realign any that are circling or crossing.
It is interesting to note that you have also found that banksias in pots seem to thicken nearly as fast as those planted in the ground. This is something I have previously commented on and i believe Grant Bowie also noted. Grant recommended just slip potting banksias into larger pots each year with little of no root pruning to get maximum growth.

[Rory]

I am absolutely loving Banksia ericifolia 'little eric' at the moment. The foliage is tiny, usually no more than a few cm's long.
I've acquired a few specimens over the years, and was pleased to see this one now showing me a tiny Banksia flower (inflorescence).
So far the flower is about 6mm wide and about an inch tall.

By memory I think I've had the specimen for about 2 or 3 years, and originally root pruned and cut back hard and kept in an 8 inch orchid pot and just cutting back about once every 6 months. I DO NOT use liquid fertilizer on it, ... so I only use slow release osmocote native fertilizer granules.
I have stopped using any form of liquid fertilizer on my banksia bonsai.

BanksiaFlower.jpg

[Grainer]

I love Banksia.. I have
2 large Marginata
4 Serrata and
about 60 Integrifolia on the go atm