AusBonsai

Hi

Can anyone confirm whether 7mm minus scoria can be used 100% for growing medium?

Today i placed a prunus in practically 100% of this medium.. only additions was fertiliser and little pine bark.

Would this harm the tree?

What would people add to scoria blend?

Scoria can have a variable ph from neutral to alkaline and is dependant on the batch and source. If you wash off the muck /dust it can be a good additive to a mix but if you are using it as 95-100% you may need to fertilise more often to avoid leeching. Scoria like quartz has 0 buffer capacity, (if for any reason the ph of your soil/medium changes then it will do 0 to resist the change in ph.
Best way to find out if scoria works for you is to give it a try, just don't put anything expensive in it till you know how it performs.

Thanks for replying.. say i use 50%.. what are my other options n alternatives?

Anyone else with info on how they use scoria plz share

I use scoria as a layer in the bottom of all my grow pots and poly boxes, as my Diatomite/Zeolite falls thru
I find the roots quite happily grow down and thru it,but think that as the holes are quite large it will dry out quicker than diatomite
Also i have trouble finding the smaller sizes here ( 20 mm) and do not feel like breaking it apart.
It is also much heavier than diatomite mix

great to use as an additive, but i would not use 100% out of preference

Ken

Dear Mr Specimen.
I you search soil mix you will find a lot of posts and debates about soil mixes and additives.
I'm with KC, it's good as a drainage layer but as a 100% mix my prediction is the roots will run to the drainage holes and out the pot looking for something to latch on to for a feed.

I recently read a post on here, I think it was either pup or alpine, but one of them said they use a Scoria and Pine Bark mix for all their pots.

I know some people that use 100% diatomite for certain things but personally I use 50%/50% diatomite and sieved potting mix ...and I use this mix for everything from Azaleas to Natives with great success
I have never used 100% scoria though as it has no nutritional value and your feeding regime would have to be spot on not to mention watering

Cheers
Barry

Hi Guys , i have used soft red scoria for well over 5 years .It has been tested here from 50-50 pine bark and scoria to 100% scoria . Today all my plants grow in a scoria blend from 50-50-to 90-10 scoria and aged pine bark .Watering is the same for all species pines to maples . The roots DO NOT attach themselves to the scoria as some suggest , a simple shake or a vigous shake and all the material basically drops off leaving a very nice clean root mass .

My big JBP was grown in 95% scoria 10 % pine bark and watered daily for 2 years , my Shimpaku was is in a 90 blend now 80% , my Natives are in an 80% blend . None of these plants have any sign of root rot and all are watered daily during the growing season and all have exceptional root growth . If i was to increase the pine bark no doubt i could water less , but when you have a blend that works as well as this does i don't change it .There is absolutely no reason to tilt pots here in winter to increase drainage .

The pines do well if not water for a week , scoria dries out on the top from the sun but has a low moisture content relatively constant , damp but not wet .With all the testing here i don't believe i can over water this blend . All my Yamadori pines go straight into an 80-90 % and the success rate has increased . I have never used recommended bonsai mediums so i cant comment on what to add to the scoria other than what i have tried and tested in my containers plastic terracotta ceramic even the grow beds have a scoria content . The fines or mud from any material sold as Minus must be washed out or you will have rotting issues . The scoria used here is from Beveridge Quarries so other material from other states may not perform satisfactorily . One must trial and test in order to achieve success .

Cheers Alpineart

Where i work we used to hold around 200 tonne of 7mm minus scoria shipped from vic as an aggregate for the besser blocks we make. Now a cheaper alternative has been sourced and we no longer get it, i wish i knew to stockpile it at home then, beats payin 8.95 for 15kg bags at bunnings like i have been.

Guys thanks as always for your help advance input.

If u r in melb West suburbs, Midway has good supplies of materials and i just purchased a whole bag of 7mm scoria for $10.. dayam heavy so its a decent size bag.

Does anyone know whether it I s soft o r the hard type? Certainly is porous

I have mixed scoria and. Diatomite 50 50 and I'm getting good results nice root mass easy to bare root . Just like alpine said . I pay 6 bucks a bag in Sydney.

Hi T S , The difference between soft and hard is the hard is more like glass and shatters when hit , whereas the soft scoria crushes even under impact . They are both porous however the absorption and water retention is far superior with the soft scoria.I use hard marble for wet beds as the retention is less however they work better as humidity trays and doesn't break up or crush when i throw the pots and containers around on them . Hope this helps .

Cheers Alpine