AusBonsai

Have a b,serrata and it does seem to get some brown and yellow leaves but now has more than before, iron deficiency? Do I use iron supplement or a good fertiliser for banksia/natives?
Here it is
Many thanks

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Looks totally normal to me. The browning is normal death of old leaves. Note the dead leaves are mainly at the lower end of the foliage, meaning the new leaves are in great health and with no problems. Use a very low dose fertilizer if you are not familiar with the history of its fertilizing.

EDIT - I use powerfeed for natives and osmocate native slow release fert, but if its the first time you are fertilizing, I would only use about 20% strength, seriously. I used 33% strength the first time, and it sulked for quite a while when I first used it on serrata. After this, I gradually built up the fertilizer regime and it came good.

They love lots of sun and a well draining mix.

It's not iron deficiency. That appears only (at first) in the youngest leaves. I would look more to nitrogen and/or potassium.

Banksias like a bit of the old blood n bone.
Cheers
Kirky

TI have that added iron chelates helps all my natives about once every 3 months. All of my trees get a dose of micro elements, every 6 months.
It has worked for me since I started my Bonsai journey.

Cheers Pup.

These are also known as trace elements. All frets have the in minute amounts, as we water frequently we do tend to lose them.

Cheers Pup