Australian Native Plants in our gardens

[Paul T]

Diane,

Some of the Scaevola are excellent groundcover plants, supressing weeds more than adequately.  Hibbertia are another genus that has some good groundcovers from small groundhuggers to much larger growers that can climb as well as cover.  Some of the Dampiera should do well, as they grow here fine (OK, I'm only talking -8'C, but that still should cover a lot of climates up there), climbers such as Kennedia and Hardenbergia should do OK for some of you I would imagine, although they are evergreen and I don't know what full snowcover etc would do for them. I am not sure what exactly the Pacific Coast covers by way of climate extremes, but there should be a lot of our plants that should grow there.  The few I have mentioned are just off the top of my head, without actually thinking too heavily about it (well it is a weekend after all.  ) and there are heaps of others.

[Diane Whitehead]

I'm making a seed order to send to Nindethana, and I will be trying
lots of small plants.

If the plants you grow can cope with -8, they should do fine here most
years, unless they abhor winter rain.

[Paul T]

Diane,

The plants I grow here in my own garden will get -8'C in the open, but not as cold as that under canopy cover etc.  Those in the ANBG are a different cup of tea, as the ANBG is located on the side of a hill and set up with microclimates in areas to minimise frost (i.e tree cover etc) for those plants that struggle with it.  The biggest help though is the hillside effect, where the cold pools at the bottom, minimising the frosts within most of the rest of the site.  Seeing some things growing at the ANBG has inspired me to try them here in my garden if I can locate a source for the plants.  Many of the things I see at work are pretty hard to find a nursery that sells them.

If there is any help I can give in working out which is likely to survive in my garden (and therefore over in North America) just ask. 

[Maggi Young]

The following posts are copied from a Flowers and foliage now December 2008  page
( http://www.srgc.org.uk/smf/index.php?topic=2737.new#new ) because the subject is relevant here....



Quote from: Paul T on December 27, 2008, 10:38:38 PM
Due to their intolerance of Phosphorus I do tend to keep many of the Proteaceae family in large pots where I can keep their root system separate from the other plants in my garden.  They rather like the extra drainage as well.

Paul,
I would be glad if you'll explain this.
Why do you keep those plants in pots? Does your soil contain too much phosphorus or do you use a different fertilizer (which?) for the pot-grown species?
What kind of symptoms do plants show when they received phosphorus in excess?


Gerd Knoche

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Gerd,

The Proteaceae family have roots that are designed to extract the maximum phosphorus (I'll refer to it now as P, as in NPK) from extremely poor soils (South Africa and Australia have some of the oldest and most P depleted soils on the planet).  As such, the addition of P rich fertilisers is deadly to most of the them.  By putting them into pots I can give them the excellent drainage they require, while also cutting them off from the plants in the rest of my garden that I may apply traditional fertilisers which contain P.  If they were planted amongst my normal garden plants then I would have to be careful not to fertilise those garden plants with any fertilisers that contained P, as I could easily kill the natives amongst them.  Pots allow me to "plant" these natives amongst my other garden.  Other natives that aren't Proteaceae don't have this problem and I can plant them in the garden without concern, it is just the things like Proteas (South African), Telopeas, Grevilleas, Banksias etc that are sensitive to it.  I also have a small area of my garden where I have planted a couple of the natives together in the ground, and I know to keep the other fertilisers away from them.

Has that explanation helped, or have I just muddied it up even more?

Paul T.

To minimize P for these plants I use subsoil mixed with plenty of sharp sand & grit.  Some callistemon, melaleucas and grevilleas seem to tolerate our P-rich soils quite well, but others (e.g. banksias) become chlorosed and gradually die when planted in the open garden.  Interesting that S American Embothrium coccineum thrives here.

Paul, do you know why Australian Proteaceae are P-intolerant but other families such as Myrtaceae are not (or less so)?

Ashley A.

Ashley,

I don't know for sure why, but I would be assuming that they have "P intensive" flowers, i.e they actually require more P to produce their flowers than the others do.  For that reason they have engineered roots that strip every bit of P out of the soils they are in.  I can only assume that the other families (such as the Myrtaceae you mention) do not require as much P for their flower production so they have never had the need to develp roots that extract higher levels of P from poor soils.  I tend to side with caution when i comes to Grevilleas.  Some do indeed seem to be less intolerant in a garden situation, but I prefer to take no chances.   

Gerd,

I realised that I forgot to answer your question about which fertilisers I use for my potted natives.... I just use a commercial low P Aussie native fertiliser.  I can check for the NPK ratios if you're interested?



Paul T.
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[Paul T]

Thanks Maggi.  You're on the ball as usual!!    What would we do without you? 

[rob krejzl]

Our local native nursery recommends a similar routine to Paul's for Richea's, though they're equally sensitive to excessive heat.

[Paul T]

What about the rest of the Epacrids?  Or is it just for the Richeas?

[Gerdk]

Thank you, Maggi and Paul!
Paul, your explanation is excellent. Glad you mentioned Embothrium - the only Proteacea I cultivate (in a pot).
The plant looks fine although I gave traditional fertilizer in a lower dose - unfortunalely it never flowers.

Gerd

[Diane Whitehead]

Embothrium - the only Proteacea I cultivate (in a pot).
 - unfortunalely it never flowers.

I imported a Norquinco form from Hilliers.  It took 32 years to flower, but now flowers
every year in the garden with rhododendrons and a Moroccan broom as company.

[Paul T]

Gerd,

I have no knowledge of Embothrium at all, barely even heard of it.  I'm glad that Ashley was able to provide the info on it, because you would have had me scratching my head! 

[Gerdk]

I imported a Norquinco form from Hilliers.  It took 32 years to flower, but now flowers
every year in the garden with rhododendrons and a Moroccan broom as company.

In this case I am looking forward to my 90th birthday - hoping the plant is with me then 

Paul,
Sorry, I mixed up your answer with Ashleys!

Gerd

[Lvandelft]

Very interesting discussion I just found here!

Gerd,

I realised that I forgot to answer your question about which fertilisers I use for my potted natives.... I just use a commercial low P Aussie native fertiliser.  I can check for the NPK ratios if you're interested?
Paul T.

But in relationship to our 'normal' rock plants I would love to know which fertilizer you use Paul.
We used to grow many plants for visual effects and noticed when for instance the stock plants of
Aubrieta got short of P, they flowered not so good in spring after been divided and potting in autumn before.

[ashley]

I would be assuming that they have "P intensive" flowers, i.e they actually require more P to produce their flowers than the others do.

 

Thanks Paul and Maggi.

Very interesting Paul; I haven't come across the idea of 'P-intensive' flowers before.  Presumably part of the Australia flora evolved in soils that did not require adaptation to very low P levels, whereas Proteaceae predominantly did.  However in general the P-intolerance must reflect evolutionary conditions rather than family, so that very different plants from separate families share this trait.  By contrast, South American Proteaceae evolved in young soils where P was abundant.

A mix of ericaceous compost, rather than the subsoil I use, with sharp sand and grit is recommended here: http://www.thompson-morgan.com/info/articles/proteas-from-seed.html

[Paul T]

Ashley,

The "P-intensive" idea is my own rationalisation.... it is the only reason I can come up with for them evolving roots to get as much of it as possible from a depleted soil.  The P-intolerance may have been evolved by an ancestor, that then passed that trait on through speciation afterwards?  That may explain why so many of them have it, yet have such a wide variety of conditions they come from?  I really don't know for sure the "why" of any of it.

[ashley]

On the Agriculture Western Australia site (http://www.agric.wa.gov.au/content/HORT/FLOR/CP/F06901.PDF): '...in our experience the phosphorus intolerance of Proteaceous plants is vastly over-rated. If such plants are raised from the start with a complete fertiliser they do not develop the proteoid root structure that leads to phosphorus sensitivity and indeed respond very well to normal fertiliser regimes.'

Nevertheless even seed-grown Australian Proteaceae seem to show P-sensitivity, if not the full-blown intolerance of plants transferred from a P-poor soil.  Conversely some grevilleas for example (like 'Canberra Gem') are quite happy with 'normal' P levels.

Am I wrong in thinking that some non-Proteaceae also show P-intolerance Paul?