Banksia and fertiliser

For many years there has been a myth that ‘normal’ fertiliser will kill Australian plants.

The truth is that most Aussie natives don’t care. Many actually grow way better when they have access to reasonable levels of P so they grow better when fertilised with standard fertilisers. I have actually come to the conclusion that many of my early failures with Australian native plants can be attributed to starvation because I was too frightened to fertilise.

Some of the proteacea plants are sensitive to P but astute plant persons will note that this group also includes South African proteas so P sensitivity is not just confined to Australian species.

Recent work done with plants from the proteacea family is showing that P is not always fatal to these plants. If they are underfed, banksias and proteas will develop special ‘proteoid’ roots that absorb all available P. This is how they thrive in the poor soils of their natural range but it is also the aspect that causes problems when phosphorus suddenly becomes available because the proteoid roots are so efficient that the plant can die of a P overdose. In the picture below you can see the distinctive ‘starburst’ pattern of proteoid roots on a potted banksia along with normal root structure.

Proteoid roots on Banksia

Proteoid roots on Banksia

Plants that grow up with higher P levels don’t develop proteoid roots and can tolerate normal fertiliser like any other plant.

Here are the results of an experiment carried out at Shibui Bonsai over the last 12 months. A number of banksia seedlings were pricked out of a seed tray as normal when they were a few months old. I potted half in mix with low P ‘native’ osmocote. the remainder were potted in mix with standard osmocote and placed alongside the others. Since then they have all received the same supplementary liquid fertiliser, water and light.

The results are very clear. All the plants in normal mix have grown strongly and are healthy green. All those in the mix with low P osmocote are yellow. Many are stunted and a number have died. While this may not be totally the fault of the fertiliser I think it is pretty clear that banksias can grow happily with standard fertiliser.

Alternating L to R Banksia integrifolia with 'native' osmocote and 'standard' osmocote

Alternating L to R Banksia integrifolia with ‘native’ osmocote and ‘standard’ osmocote

Left - low P 'native' omocot mix; Right - 'standard' osmocote mix. 11cm pots.

Left – low P ‘native’ omocot mix; Right – ‘standard’ osmocote mix. 11cm pots.

I think the results speak for themselves. I’ll be giving all my banksias the same mix as my exotics from now on.

If you have banksias that have been underfed you do need to be careful about applying too much P too quickly. Studies have shown that you can increase the amounts and frequency slowly and the plants will gradually adjust, shedding many of the proteoid roots that they no longer need. There is also growing evidence that you can manually remove most of the proteoid roots when repotting and the tree will be able to tolerate higher P levels immediately.

Repotting natives

I usually repot any native plants in November or December. There were plenty that needed doing this season because I had not repotted for a couple of years. I find that many native plants grow lots of fine roots in the pots and quickly get to the stage where there is no room in the potting mix for water or air to penetrate. This mans that it becomes increasingly difficult to keep the mix hydrated and I have lost quite a few trees because I have not repotted often enough. Continue reading

2016-17 Catalogue

Spring has been very busy for Shibui Bonsai. We had a trade table at Canberra Bonsai Society show and supplied more stock for Bonsai North West spring show in Melbourne at the start of November. Our local Albury Wodonga Bonsai Society staged exhibitions at both Albury Show and Myrtleford show.

Now that spring is over I have finally managed to find time to take photos of the trees on the sales tables and get them up on the Catalogue page. No descriptions yet this time but I think you can probably get a pretty good idea of the trees from the pictures. Just email if you need more info on any of the trees featured.



Late winter is typically busy at Shibui Bonsai. Trees in the grow beds must be dug, pruned and assessed. The best are potted up for you to purchase. Others are replanted to continue developing. A few that don’t look like measuring up are consigned to the scrapheap. Continue reading

Autumn pine work

The new shoots on Black pines have matured so it is time to thin out all the new shoots that have grown since decandling.

It is important to know that this is part of the technique used to REFINE MATURE pines. Younger, developing pines should be allowed to grow freely to gain strength and size and cut back hard every couple of years. Decandling is used to ramify the branches on trees that are closer to being mature bonsai. Continue reading