Premium potting mix = 28% large, un-composted woodchips

[gtarman]

So being the raging socialite I am, I decided to spend Saturday night doing a gardening experiment...

My one gripe with my go-to premium potting mix (which all commercial potting mixes seem to be equally guilty of) is that it always seemed to contain lots of large un-composted bark pieces and woodchips.

I suppose they put it in there to increase drainage (and/or profit margins) - but it seems quite poorly suited for this (drainage) because it's semi-absorbent anyway, and it also encourages the wrong kinds of bacteria and fungi, and creates a generally unpleasant environment around the root-zone of your plants (slowly rotting wood = not good).

So I took to it with one of those generic garden sieves - and the end result was a bit shocking. From a 25L bag of potting mix, 7 litres of it was un-composted bark and woodchips of around 1cm+ (most were a bit larger). That's 28% of the entire mix!

But the stuff that makes it through the sieve is glorious to behold - if potting soil were ever to be on a billboard, this is the stuff they would take a picture of. I had to consciously stop myself from running my hands through it's dark and fluffy depths several times after what could have been minutes or hours.

It can be a fair bit of work depending on your setup...but for the pickier plants and as special treatment for the prized favourites of your collection I'd say it's definitely worthwhile.

You may or may not also want to replace the bark with other, more suitable drainage materials like coarse sand, pumice/grit, charcoal etc depending on what you're going for.

Over and out.

Edited August 17, 2013 by gtarman

[Bert&Ernie]

What a crock hey. That's why I make my own potting mix.

[Bigred]

We should start a thread called" That sould not be here" about al the crap you

get in potting mixes . I get nail's plastic and heaps of other crap in there.

[Stillman]

We use Searls potting mix IME this is the most consistent product on the market. 18 for a 60litre bag I think which is alot of mix.

[gtarman]

^ wow, that's pretty cheap. I've tried that one and had some good results with a couple of plants, but I think it could probably use a better wetting agent (can't remember if it has one?)...I found that once it dried out it was a bitch to re-hydrate (moreso than usual anyway). Can't remember whether they use peat or coir either...but my preference is usually for the latter

Edited August 17, 2013 by gtarman

[Stillman]

Not sure on the wetting agent. I use the premium potting mix for everything sometimes I add a little sand but lately I have just let it go as is. I feed twice or three times a week in summer. You get the old shitty bag but as a whole for an off the shelf product thats cheap its not to bad.

Edited August 17, 2013 by Stillman

[AndyAmine.]

Searls make a good cacti mix as well, I throw a bit of CSS, charcoal, aged manure and pumice or scoria in and they love it.

Yates makes a good liquid cacti fert that the trich's enjoy but I worry about heavy metal levels in ferts not sold for use on fruit/veggies so only use it on ornamentals,

Edited August 17, 2013 by AndyAmine.

[paradox]

we have some nice soil here in the valley down on the flood plain, nice sandy loam. i guess i'm lucky for that but i reckon you could use almost any half decent loamy soil as a base..

i just dig up 2/3 of a barrow of top soil & mix it up well with a third of a barrow (you can even go half/half depending on how you feel or what you're potting up etc) of good, reasonably fine compost & bobs you uncle, costs me zilch unless you count the effort to make the compost... even if i don't have any of my own compost on hand i will just buy a $6 bag of half decent compost & use that.. $6 for 100L of the best potting soil you'll ever lay your eyes on, you can't go wrong... well you can but jeez, it doesn't matter how bad you mess up the mix or whatever you couldn't do much worse than even the best commercial potting mix's imo. i've never had better potting soil than this..

edit: you could get a lot more fancy with the mixes too depending on what your needs are or if your base soil is poor, but thats easy too & cheap if you do it right also

Edited August 18, 2013 by paradox

[Sallubrious]

You're lucky to live in an area with easy access to good soil like that. Mixes made that way tend to hold a lot more water than a commercial bark mix and tend not to dry out in hot weather like a bark mix.

I used to buy loam or sandy loam from nurseries and do the same thing but it's becoming difficult to find real loam in many nurseries these days. Most of them have that crap they call "super soil" which is anything from sand mixed with compost all the way to half composted bark mixed with manure. I've never seen it made with real loam.

With the sandy mixes after a few waterings all that's left is sand and the compost mixes just dry out too quick. Whenever I see "super soil" at a nursery I like to ask them for a soil analysis just to take the piss, they never can supply any documentation, it's just a mix of shit some bozo has mixed up with a front end loader that they think looks good.

[paradox]

yeah i think it's good to add some larger drainage material. the main reason i like my mix is that it's preparing all my young trees to be planted into that very same soil in the valley, so they tend to adapt very well to being planted out

[irabionist]

I'm yet to get a Cacti or seedling mix with no bark or woodchips

[tedzr]

I've used Debco garden mix for my last couple of bags, priced similar to the other premium bags and practically no wood chips, although there is a small percentage of finely shredded wood material in there. Mix with sand, charcoal, perlite and volcanic stone + some additional slow release ferts, that's my mix. I would like to add more organic material to my mix though, I'm thinking of getting a compost / worm farm thing for the balcony (apartment dweller) as I don't want to rely on chemical ferts too much more as they are bad for the environment and only provide npk, not the more complex elements that I imagine could improve soil quality. I used to get that cactus mix and just run it through a siev, but it's far too expensive for the huge percentage of bark. If you're gonna do that, just buy some cheap garden mix, siev and add drainage and other elements as required.