Where can I find a cheap/ light weight potting mix?

[stevelau1911]

All my seedlings will eventually need to get up-potted, but I'm not sure where I could get a bulk supply of light weight potting mix that large nurseries use. Does anyone have any idea where I should look?
What do most people use?

I grow more than just bamboo.

[foxd]

I normally just buy the largest sized bags of Miracle-Gro potting soil I can find. I did find the Kroger Gas Station selling bags of Miracle-Gro for very cheap last fall. I was really tempted to buy the whole flat, but couldn't justify having that many bags of soil sitting around.

[stevelau1911]

I think I found my answer. They sell 55 or 70 cubic feet of Promix BX at many distribution points throughout the United States which is what they use at many commercial nurseries. I hope this stuff works.

Does anyone else use this stuff? It is supposed to be around 250$ for a 70cubic foot bale which should be enough for lots of plants. I find that standard top soil and whatever they sell at the retailers is too heavy for what I'm aiming for.

[Alan_L]

There's a big difference between potting soil and potting mix. Potting mix is light because it doesn't contain soil, and potting soil, well, contains soil.

Promix is pricey from what I've seen. I haven't used it. I usually mix my own for larger plants, or just use the cheapest bagged mix I can find for smaller plants.

[needmore]

I've morphed from 2cuft bags of Miracle Gro potting mix @ $11 each, to 2 cuft Schulz potting mix @$7.89 each, to mixing those 1:1 with 1 cuft bags of Schulz Garden Soil @$2.89 each to now I think I'll switch the the straight Garden Soil. I think the only difference is the tiny bit of vermiculite they use in the Potting Mix and I think the bamboo will be fine w/o that or I can always buy a bag and mix it in if I want. That would be under $6 for 2 cuft and I can usually get 4-5 squat 5's potted from 2 cuft.

Non-bamboo may be fussier and need better quality. The main thing to skip is those 40lb bags of $2 or less Top Soil with no peat, bark, or compost mixed in, that stuff is usually black cement for plants.

[stonecrabber]

Here's my recipe
They sell pine bark mulch at walmart 2 cubic ft. bag for like 3.00
You have to look at the stuff closely, it comes in 2 different types
pine bark nuggets and pine bark mulch. You want the pine bark mulch.
Then get a couple of bags of cheap potting soil.
They come in about 1 cu. ft. bags for about 2.00 ea.
In theory you'll get 4 cu. ft for about 7.00.
I've used this mix for quite a few years and it works pretty good.
If the bark is not finely ground it won't mix up very good. I have a piece
of hardware cloth(1/4 mesh) that I used to screen the bark. Its a pretty
simple thing just a 2x4 frame with the hardware cloth attached on the bottom.
I set the frame over my wheel barrow and dump in a little bark at a time and
just sift the larger pieces out. When I get a lot of the larger stuff, I just kind
of rub it against the screen with my hands and it breaks up into smaller pcs.
If you don't screen it you'll get a lot of floating bark the first couple of times
you water. I have used the bark unscreened and it works OK,but the screened
stuff is definitely better.

Then just mix it 1 part potting soil and 1 part screened bark.
You have to mix the stuff pretty good.

I know it sounds like a lot of work but you can screen a bag of bark in less
then 15 minutes. The mixing doesn't take long either. Its a pretty light mix
and it doesn't turn into 'black cement'.

[stevelau1911]

That sounds like a pretty good idea.
I still haven't decided my exact mix yet but I'm considering something like 50% peat moss, 30% pine mulch, 15% potting soil and 5% regular clay soil to stabilize the mix. Buying Pro-mix would be around $28 per 3.8cubic foot bale, but getting the materials to make my own mix at the same amount would likely be less than half that cost.

I've figured that bamboo's not that picky about soil so aiming at making it as light weight as possible sounds right. I'll need to look for that pine mulch in bulk and find the rest of my materials at the cheapest store possible, likely Lowes or Wal-Mart.

[needmore]

Here's my recipe
They sell pine bark mulch at walmart 2 cubic ft. bag for like 3.00
You have to look at the stuff closely, it comes in 2 different types
pine bark nuggets and pine bark mulch. You want the pine bark mulch.
Then get a couple of bags of cheap potting soil.
They come in about 1 cu. ft. bags for about 2.00 ea.
In theory you'll get 4 cu. ft for about 7.00.
I've used this mix for quite a few years and it works pretty good.
If the bark is not finely ground it won't mix up very good. I have a piece
of hardware cloth(1/4 mesh) that I used to screen the bark. Its a pretty
simple thing just a 2x4 frame with the hardware cloth attached on the bottom.
I set the frame over my wheel barrow and dump in a little bark at a time and
just sift the larger pieces out. When I get a lot of the larger stuff, I just kind
of rub it against the screen with my hands and it breaks up into smaller pcs.
If you don't screen it you'll get a lot of floating bark the first couple of times
you water. I have used the bark unscreened and it works OK,but the screened
stuff is definitely better.

Then just mix it 1 part potting soil and 1 part screened bark.
You have to mix the stuff pretty good.

I know it sounds like a lot of work but you can screen a bag of bark in less
then 15 minutes. The mixing doesn't take long either. Its a pretty light mix
and it doesn't turn into 'black cement'.

Sounds like a good mix, the 'black cement' comes from those 40 lb bagged top soils that have no amendments at all but your pine mulch method would sure help that out. I used them un-amended once and water would just pool on top and then they'd dry out into a slab, I had to repot everything .

[stevelau1911]

I just bought a bunch of peat moss and pine mulch which were fairly cheap and I think that stuff can make up around 85-90% of my potting mix.

I've been considering adding top soil to my mix since it's only about $1 per 40lb bag at around 5%, but I'm a bit skeptical if it is supposed to turn into a solid slab. Does that also apply even when it is a small portion of the mix?

My other options that I can get for free are leaf/grass clipping compost, horse manure and garden soil, but I'm a bit lost on what can add nutrient value to my mix. I know retailers also sell vermiculite, perlite, ironite, and green sand in order to amend the soil, but it is hard to choose the right one. The last thing I want to do is have to re-pot all my plants when I find out my mix didn't work.

My biggest concern is cutting cost so I'm trying to find the cheapest growing mediums possible. I'm not wasting 30$ for a 3.8 cubic foot of professional grade mix when I can produce the same thing for a lot cheaper.

[foxd]

I've been considering adding top soil to my mix since it's only about $1 per 40lb bag at around 5%, but I'm a bit skeptical if it is supposed to turn into a solid slab. Does that also apply even when it is a small portion of the mix?

Your might shop around and try different brands of cheap top soil. I found a good brand at Menards that the bamboo seem to like. (I'm drawing a blank on the name at the moment.) I avoid buying top soil at Walmart because the brand I got there set up like portland cement and killed plants.

-----

I just did a quick Google search and it might be "New Plant Life" topsoil based on the negative reviews. On the bright side, the negative reviews involved it being wet and finding stuff growing in it, like grass and mushrooms.

[Alan_L]

There's a difference between bagged "topsoil" and bagged "garden soil" usually. The "topsoil" is usually unamended and is the cheapest stuff. "Garden soil" or "potting soil" is usually amended with other stuff: peat, compost, etc. I'd never use straight topsoil in a container of any kind, and would probably only use it in my yard to fill a hole. If I wanted to use topsoil for planting in my yard I would mix it about 50/50 with compost.

Adding some amount of the topsoil to the other ingredients you mentioned is good... I would say even recommended, especially for larger plants. Adding compost is good too. Gotta make sure it's mixed well though so there aren't "clumps" of topsoil or any of the other ingredients.

When I create a general mix for bamboos and my other plants, I use this approximate recipe:

1 part peat (may try coir this year for environmental reasons, but it's harder to find)
1 part compost ("leaf mold")
1/2 part bagged topsoil (cheapest, unamended stuff)
1/4-1/2 part perlite
"some" organic fertilizer (optional)

[stevelau1911]

1 part peat (may try coir this year for environmental reasons, but it's harder to find)
1 part compost ("leaf mold")
1/2 part bagged topsoil (cheapest, unamended stuff)
1/4-1/2 part perlite
"some" organic fertilizer (optional)

Kind of sounds like what I had in mind. My goal is to aim for $.17 per gallon as far as the cost and make the mix just as functional as the professional mixes. I'll including some of the free manure and material from my compost pile too, but not too much since it is heavy.

[spiros]

Several years ago I bought the 40lb bags of topsoil (the cheapest) and mixed in a bag of perlite ($3-4) and vermiculite. I used it for houseplants and the soil is still soft and airy. Perlite doesn't decompose like the fine bark mulch so its there forever. I have stopped using vermiculite as there was an asbestos issue (not really sure though).