AusBonsai

After years of hearing differing views on how banksias react to fertiliser I decided to do my own test.
last year I potted up some B. integrifolia seedlings. Half went into mix with low P 'native' osmocote. The other half were potted up with the same potting mix but with an ordinary osmocote at the same rate I use for all the other species. The pots were placed together on the bench so have all received the same light, water and supplementary fert since.
I think the photos speak for themselves.
Photo 1: alternating left to right - native and standard osmocote mix. Even the ones in larger pots showed the same results In all cases the plants in the native mix are yellow and smaller than the standard counterparts. You can see that some of the native mix plants are severely stunted. Several have died while all the ones put into the standard mix have grown well and are a good healthy green. I have just potted all these on into 11cm pots with standard mix.

I'll certainly be using standard osmocote for my banksia seedlings from now on.

Keep busting them bonsai/horticulture myths Shibui!

Perfect, I will be putting a handful on my slightly yellow Banksia seedlings today then.
I have been taking a cautious approach too as I have read the same things. Hopefully in spring they will perk up a little.

Could you check if they all developed proteoid roots, or just the ones planted in native osmocote?

Thanks for taking the time and effort for this, appreciate it.

That is certainly food for thought Neil, hahaha... ahem.

Seriously though, I use 'osmocote slow release pellets for natives' on every genus I grow, but I don't get the yellowing of the leaves.
For the Banksias I have since reduced the volume of Powerfeed for Natives to about 50mL per 9L after speaking to Grant at the CBS show last year, only because it was getting too expensive using a higher concentrated volume on 200+ trees.

Mine are all very green and in perfect health, however as I am not using standard osmocote or standard Powerfeed obviously I have nothing to compare it to.

Perhaps the Powerfeed for natives that I also use makes up for whatever is in the native osmocote native pellets.

shibui wrote:After years of hearing differing views on how banksias react to fertiliser I decided to do my own test.
last year I potted up some B. integrifolia seedlings. Half went into mix with low P 'native' osmocote. The other half were potted up with the same potting mix but with an ordinary osmocote at the same rate I use for all the other species. The pots were placed together on the bench so have all received the same light, water and supplementary fert since.
I think the photos speak for themselves.
Photo 1: alternating left to right - native and standard osmocote mix.

banksia fert trial Jan 2017 2.JPG

Even the ones in larger pots showed the same results

banksia fert trial Jan 2017 5.JPG

In all cases the plants in the native mix are yellow and smaller than the standard counterparts. You can see that some of the native mix plants are severely stunted. Several have died while all the ones put into the standard mix have grown well and are a good healthy green. I have just potted all these on into 11cm pots with standard mix.

I'll certainly be using standard osmocote for my banksia seedlings from now on.

You need to determine the real reason for the lack of growth with the native osmo though. In this case, the weaker plants are not suffering from low P as this shows up on old leaves and you have chlorosis on the young leaves. It seems more a sever Fe deficiency to me, but I'm not sure. (availability of Fe and P are intimately related to each other. The more P the less Fe and visa versa but apparently there is something else again going on here) There may be some other interaction going on between the fert and the mix. It is highly unlikely that there is not enough P in the native osmo for banksia. I am using it for a number of things, including a banksia Birthday candles without any sign of chlorosis.
I would be extremely cautious in using standard osmso long term on banksia.

Rory and Mike,
The real point in this post is that it appears banksias can grow well using standard fertilisers. There may be some circumstances where standard fert could hurt a P sensitive plant (starved plants, etc) but my banksias have been getting Thrive soluble fert off and on for the last couple of years and now I have shown that they also grow well with standard osmocote in the potting mix. At the very least I think these results suggest that further work should be done.

You need to determine the real reason for the lack of growth with the native osmo though. In this case, the weaker plants are not suffering from low P as this shows up on old leaves and you have chlorosis on the young leaves. It seems more a sever Fe deficiency to me, but I'm not sure. (availability of Fe and P are intimately related to each other. The more P the less Fe and visa versa but apparently there is something else again going on here) There may be some other interaction going on between the fert and the mix.

I agree that these plants should grow reasonably well with 'native' osmocote. The batch I have is a few years old and may not be effective now. I'm also not sure whether it has trace elements in the formulation but I do know the standard one does have TE included.
Again I stress the point is not that native fert are no good, rather that standard ferts are not necessarily deadly to natives, including banksias.
As for long term that remains to be seen.............

For me it is one less hassle mixing different mixes for different classes of plants - they can all get the same now.

Yes, that is kind of the same deduction grant advised me about using standard fertilizer as well.
I totally get what you are saying. It is very interesting though that you got such poor results from the ones with native osmocte. Perplexing?

At any rate, this made me wonder about my banksia so I took a closer look at mine last night and I think a few of them do actually have pale green new growth, while others are strong green. I may have assumed they were all solid green growth.
The integrifolia sentinels (small leaf) are the exception and have brilliant strong green new growth using native fertilizers
There are a few integrifolia and one marginata with slightly faded green/yellow new growth, while the others are strong green.

I am on the other side of your coin Neil, haha... in that I use native fert for everything and can't be bothered using regular fert .... makes it easy. Maples, lantana, bougy, natives.... they all get native fert.

I didnt mean for my post to come across as contradicting you, more so just an observation with my experience using it.

Perplexing?

Maybe Mike is correct. Maybe native ferts do not have all the elements needed to grow really healthy plants?

I took a closer look at mine last night and I think a few of them do actually have pale green new growth

It is good that you are able to reconsider preconceived ideas. When someone only has trees grown by one method how can they compare? Yours look OK next to each other but how will they look compared with plants grown using different methods? (I'm not just talking about native V regular fert, all hort methods should be constantly reviewed and questioned)

For a while I too used native fert on all species and everything grew but now going the other way and getting better results.

[/I didnt mean for my post to come across as contradicting you, more so just an observation with my experience using it.quote] No need for apology to me. I welcome all informed debate and ideas. keep on questioning what you see and what you hear

Hi Neil,
All my trees are fertilised exactly the same. With both slow release and liquid fert. The only time I do anything different is if I have just bought a new tree and have no idea the last time it was fertilised. Then I fertilise 1/2 strength to begin with then it's the same as everything else. All my natives are treated the same as my exotics and never had a problem.

Josh

I have been using std Osmocote in all my Bonsai mixes and have used dynamic lifter as a fertiliser on all my natives, being Bonsai or garden plants never had a problem with any of my plants. I just did two Banksia that where totally pot bound and used my mix and they are bouncing back nicely.