Drainage Layer?

[Jamie]

gday mojo

that pine i recieved of you, which by the way is going great guns had a layer of smooth round gravel about 6-8mm in size, i figured that was for a "drainage"
layer persay?. i will use that term so we can keep it easy to understand.


jamie

[hugh grant]

I've wondered why the Japanese have so much concern over having a drainage layer, and I think Jamie just explained great. I've used a drainage layer on my trees for a little while now by placing a very shallow layer of about 3-5mm plebbles that are for top dressing on the bottom of my pots so the water can drain away more freely and not sit in the bottom as much, but I think now I totally understand it and the other purposes.
Since I'm not a very big fan of putting pebbles on top soil of my trees, I like to say:
'the pebbles belong on the bottom not the top!'

Hugh

[Jamie]

gday hugh

what needs to be understood is that the "drainage" layer doesnt actually improve drainage. what it does is manipulate the water table like i explained, which i amso glad i made it understandable the first time!

a pot with a medium in it will drain as much as it can than depending on the medium being used there will be a certain amount of water retention. in the article that brett linked which is where i took my understanding from has a great way of explaining the way a pot with a medium works.
its the part where he talks about the sponge, take a look its very interesting and will save me having to type it up

jamie

[hugh grant]

Thanks Jamie, I do under stand now what it actually does inwhch is what i was saying that I now understand the reason for it and not what I actually thought.
I'll make sure I read the article, it looks interesting

Hugh

[Jamie]

cool man glad you understand it a bit better im happy to have been able to pass a bit of knowledge on that will help it always helps to understand why things are done and not just do them because that is how it is supposed to!

jamie

[Grant Bowie]

Hi Grant,
I use steel mesh on my growing benches and leave planty of space between my trees this allows plenty of air circulation around the pot, so I don't use a drainage layer in my soil. The mixes I use are fast draining anyway and are set up to be watered often during the growing season and to withstand the 6 weeks of fog, mist and drizzle that we get in July/August.

Cheers,
Mojo

I also use steel mesh under a lot of my trees. Otherwise they are on the cement paver topped turntables but still get good aeration.

I will be experimenting with the mixes and drainage to see what happens.

Thanks for all your input and forebearance.

Grant

[Bretts]

If we all get it so easy why are so many others around the world believing that a coarse layer impedes drainage. ? Even the guy who wrote this article!

Can't agree more about understanding why something works is advantageous Jamie. I was talking to some one the other day that said they just did what they where told and I will not knock that. Some times I wish I could be like that.
But if you are able to understand what you are really doing when you manipulate the grades of medium in a pot then this opens up lots of potential.
Using a coarse layer we can literally make a pot smaller than it is so there is not too much water for an immature root spread but with the large coarse layer there for the roots to extend into if they want you could also get the growth of a larger pot.

[Jamie]

basically yes brett

by manipulating the layers of the medium what you are doing is working with the tree and plan it out for the amount of time it is expected to be in the pot. take a tree you expect to be in the pot for three years, adjusting the layers to suit this would expectantly make for a better growth rate as the first year while it was establishing itself in the finer layer, getting the moisture it needs to establish and start getting ready to power on from the more moisture holding capacity of the finer grade through water tension, the second year where it can essentially strectch itself into the medium layer, eventually filling up the pores while getting the maximum out of the tree. then the third year where it will have filled out the pot into the largest spaces essentially filling the coarse layer and turning it into a medium/fine layer making the moisture and nutrients available to the tree, giving it basic maximum growth potential in a pot. essentially.

im not sure why it is a hard thing to digest for some people, although it took me a few times to read over it and understand the concept, process and reasoning behind it, before i fully had an understanding and grasp of the theory. when i start repotting my trees again i will be using this theory process and testing it all out, really i would like to do that now, but havent got what is needed to try it at the moment.

probably would be handy to get some larger size akadama- medium and large for this as i dont think i could get large particles of diatomite. although other mediums could be used as replacements for this. i will be having a look around on the weekend see if i can find replacements. i might have some seedlings out the back aswell which would be a good thing to use as a test subject, same age etc. so testing should be clear.

jamie

[Bretts]

KC uses scorio as a drainage layer with diatomite I think
I have already started using this idea. I had a olive that the roots had not grown great on so it was staying too wet at the bottom of the bonsai pot. I decided it would be a good idea to put the tree in a more upright pot. With varying grades of medium so the water was up the top around the roots with a coarse layer down the bottom that would not be saturated but the tree could grow into when it got going.

[bodhidharma]

Great subject, my head hurts trying to read it in one sitting. I have always used a drainage layer. In my Bonsai pots i lay a handful over the holes and then fill in with my potting mix. I have never had a whole bottom layer in the pot, just over the holes. I did this to stop the holes from clogging up and have always been of the belief it was for drainage reasons. I was told this by my mentor and have just always done it.

[Pup]

This is an interesting thread is it not. Unfortunatly I cannot add to much to it. I have not used a drainage layer in any Pots I have used it on Slabs.

Very early in my Bonsai Journey I read an article on water perching saw the reason for not using and have not.

Although after discussion on, Soil mixes with Grant last month, when he was here, in the west,the has come to me that maybe I should change that practice now.

As I have noticed some of my trees that I have changed to Akadama, not draining as well as my other trees, before you tell me yes I sift all the dust out.
Trees that are swamp lovers seem to drain more freely or is it the trees using more moisture

Cheers Pup

[Jamie]

gday pup, im no expert on the matter by far, but feel i have an understanding of the theory.

i would beleive it would be that the swamp species you have are actually taking in the more available moisture rather than it draining better. with more water tension i beleive it allows the moisture to be readily available to the fine feeders and pipes if you will and the tree is able to take it in as the moisture is in a state that when under tension is readily available as such where as those that havent drained aswell due to excess moisture being present the tree isnt necessarily not taking up as much but the fact that there is maybe more there or less readily avalable as the water table is higher creating larger volumes of moisture.

im still not sure if i am explaining this well enough and easy enough.

stop me if it dont make sense ok!

[Glenn C]

Thanks Jamie, we of lesser experience are getting a good education on soil types and structures this last week or two following this thread and the diatomite one.
After reading the link Brett added my grab of what the author is saying seems to be that he is only considering one dimension of why people add a drainage layer. For the reason he states he is somewhat correct, but his vision seems blinkered when considering your interpretation.

Am I reading you correctly to say that creating the layers allow the roots to grow through the different stages of the determined time between repotting?
That you are manipulting the water table to suit the needs of the tree as the roots fill the medium?
If I am right you have explained it well.
Seems like it would take a lot of experience to get this right for each type of tree in your own geography.
Man I have a lot to learn.

[Jamie]

gday glenn

yep you got it in one mate the article does show only a one sided veiw as such, but i beleive the way i have tried to explain things simplifies it to a degree we can all understand, i had to simplify it for myself!

working it all out for the different layers as to how much root growth you get will take a bit of time. i beleive working it out would definately be worth it though as i beleive we could get the maximum growth and health out of our trees if we get these things right along with feeding and general care

[Bretts]

Here is some more reading for you Glenn
I just found this while I was looking for NZ spag moss agian and found it answers alot of questions I have been asking myself. Thought it might be interesting.
http://www.ultragro.pl.net/mediasepc.htm
It has a great section on the drainage layer looking from a slightly different perspective.

What I found most intresting was that organic material will buffer pH changes. This is something I have thought experimenting with inorganic mediums. Slightly acidic kanuma has become highly alkaline after using dynamic lifter.
Also I have considered the high CEC of zeolite and whether that results in a salty medium. It seems it actually does the opposite and controls fluctuations.
A bit of track but thought ya's might be interested.