AusBonsai

G'day fellow Bonsai'ists..
I'm working on some "Monkey Pole" type stands for display out in the garden. Rather than treated pine or other timber, I found some already rusted heavy gauge steel tube (100x100) at a local steel supply. Some angle brackets will be welded to the top to support the rock slab shelf. I picked up some rock slabs, 40mm thick slices of both honeycomb rock and mudrock. The mudrock has an awesome texture and the honeycomb rock has a great rough edge and porous surface. A question I have is something I didn't consider when planning all this and a comment my wife made that got me thinking.... residual heat in the rock. Does anyone else display their bonsai on a slab of rock and does the heat generated on a hot day have an effect on cooking the pot? The tree's will be pines and cedars which can afford to dry out between daily waternings but I am now a bit concerned regarding the radiant heat factor - mind you, I've already spent a fair bit of money on these slabs so hoping all will be ok..
cheers. Rob..

Since you've already gone ahead with the material, there are sure to be ways to stop the heat. Have you thought about cultivating some moss on the slabs? That would help to soak up the heat...or perhaps just some shade cloth draped over the rock for the hottest days...

I'll definitely have to take a trip south to see your garden sometime, Rob! Sounds like it's pretty special.

What colour are the slabs?

Hi Rob, you will have absolutely no problems growing Pines and Cedars on slabs. I have grown mine on the concrete driveway and terracotta roof tiles in bonsai pots for over ten years in full sun. With over 50 trees JBP, JRP, Radiata, Scots to date I have not lost one. Just ensure you keep the water up to them. The JWP are in a different location as they would not cope with the heat. The only deciding factor that I see would be your potting medium. What are your trees planted in?
Cheers
Kirky

The mudstone is a very light color grey with light brown streaks - looks great wet as it almost has a timber like texture. The honeycomb is also a grey when it's dry. The porous surface of the honeycomb will hold little pools of water for a time until it evaporates. I'll take some photo's when it's all done. The slabs will just sit on the brackets so worst case scenario - will replace with timber and use the slabs elsewhere. I was sure I wouldn't be the only one with this type of set up..They will look awesome once they've been done - to display only my best and biggest pines and cedars that can handle the full sun position..
For sure Mel...let me know whenever your down this end of the country..

Thanks Kirky...
My medium of choice these days is a mix of gravel/small pine bark/Acadama/small scoria, small pumice and a little Zeo + small amount of crushed granite.
A custom mix - depending on the tree - quite freely draining but so far, working well..

Hi Rob, ok looking at your mix, apart from the small pine bark, I don't see much water retention. Are your trees currently in full sun and how often are you watering them? I find my Pines do prefer to be on the dry side.
I use the Decbo Bonsai Mix. I know it is not everyones preferred mix but it works for me. I water in summer every other to third day. Unless temps are over 35-40 onwards, or we get the drying Northerly's, then I will water first thing in the morning daily or even twice daily. Especially if the heat is continual for instance a week or two in high 30s, low to mid 40s etc.. And high night time temps. Then definately daily to twice daily. I'm in Hawthorn so it would probably be hotter here than out your way. Hope this helps.
Cheers
Kirky

Kirky...there is some organic mix in there as well..when I say small pinebark... I use approx. 1/4 Collectors Corner mix (I do like this mix although by itself, holds too much water imo as it does have some peat in there as well).. the other 3/4 is a mix of Damiens (Olegy) mix - he has some premium products in his mix including pumice, zeo, perlite and the decomposed granite. I grabbed a large bag of Trevors Acadama and until recently, been screening my own scoria down to fines - 2-4mm but Trevor (Dingley) also has this available as well...
Some might say there's too many products in my mix but so far, I've found it to work superbly. It does dry out in 1 day in 25+deg weather but that's fine when you keep to a good watering regime. I found that previously, using more scoria and diatomite, the mix would actually hold too much water in the cooler months. I figure that scoria does in fact hold more water than pumice due to the fact that unlike pumice that is fully porous, the little pockets and holes in the scoria would probably well up and hold water.. My theory only though and through discussion with others.
As you know, the correct mix for various bonsai is such a highly debated topic and so many opinions out there, which only lead to confusion and people coming up with their own theories.
The above mix is pretty much what I use for everything including Maples, Larches, Natives etc...I just adjust the various components to suit their requirements. ie; Maples and Larches etc, would be more water retentive with a higher proportion of the original peaty Gardenworld mix and small pumice.
It's a massive topic isn't it..??!

Hi Rob, it is a masive topic. Please don't get me wrong. You can use any mix you like I'm not dictating what to use.
You asked would there be any problem growing on slab/stone etc... And the answer is no. But before I can truely say no
Its good to judge apples with apples. Its only when you have all the facts that you can then decide for yourself.
In what you have advised, I still stand that you will not have any problems growing on your new stands.
If you do find they dry out two quickly, sounds to me like you have the knowledge to adjust your mix accordingly next repot.
Cheers
Kirky

Hi Rob, As you know I live in the hot Dry state of WA. I have grown my trees on monkey poles with tiles under them.
With out any problems, I am retired so watering on hot days is not a problem, like today 37 tomorrow the same. This is normal for us. My mix is very open and used for all my trees, even the minis and my one maple.
I do have a high humidity set up for my smaller trees.
I never sit any of my trees in water troughs, over them but never in them.

Cheers Pup.

Ok...I'm sort of convinced that I was worried about nothing..
I've been working hard over the last 18 months setting up my display areas so now getting towards the end of it all, it's all come together nicely. The rock slab stands will be a great addition...if anyone is interested, I'll post some photo's when it's all done..

Would be great to see pictures once you're done.

Yes please do post some shots.
Cheers
Kirky

I carve out the mudrock and use as pots. I find it doesnt seem to heat up much at all. It is actually quite absorbent. I know what you mean about the texture of the rock when wet, it is awesome. Would love to see you set up when done so please post pics when finished.

Josh

This looks fantastic Josh... Hmm, got me thinking now..
I've seen honeycomb rock done the same which also looks great. Do you mind me asking what tool you use the grind them out?
I have thought of doing the same and was going to get hold of a small diamond cutting disk for a 4" grinder..