Purpose/advantages/disadvantages of container ingredients

[tam91]

Interesting, any topsoil I've bought here just has black dirt. No gravel or anything.

I'll go read that link, thank you.

[shlacm]

I'd like to second the referral to Al's threads! I had NEVER been able to keep anything alive before I discovered his advice... NEVER! So, that's what I use in my containers: Al's mix! In one of the threads he specifically talks about tomatoes in containers, but I couldn't tell you which one... GW's not terribly "search friendly" when it comes to loooooong threads!!! Add to that the fact that he had/has to keep starting new ones and there must be a series of 50 or so!!!!!!

[Stepheninky]

I am using compost from the local university's ag center. (some Universities and many cities now have affordable compost and mulch that can be purchased.)
Here is there link as an example http://www.wku.edu/farm/mulchyard.html

I got a mix of the leaf mulch and sawdust/manure mix they have listed it was $125 for 6 cubic yards.

I will also be getting a load of top soil as well. Top soil though is kinda a lose term as the quality of top soil can vary greatly. Here cheap top soil would be mostly clay and rocks (lime stone). The top soil I am getting as soon as its dry enough for the guy i am getting it from is river basin soil that will also be shifted to remove most any rocks. (soil from the flood plain of the river bank) this will be 10 cubic yards for $165

I have a lot of beds to fill up etcetera, so that is the reason I am ordering it by the dump truck load.

Both prices I quoted in this post included delivery to my home. For reference 1 cubic yard = 27 cubic feet. If you notice most soils and mixes at the box stores say covers 2 sq feet but that is at a depth of 6 in so really they are 1 cubic foot in size.

So 1 cubic yard = 27 bags of top soil or potting mix.
So 16 cubic yards (16 X 27) = 432 The total price was 125 + 165 = $290 290 DIVIDED by 432 = 0.672 so roughly I am paying $0.67 cents for a bag like in the box stores for my mix I am using.

I guess the point I am making is you can look around your area and might be able to find similar compost and or top soil and get better quality while saving a lot of money. You usually can buy by the pick-up truck load as well if you do not need as much.

The above mix is comparable if not better in my opinion than MG potting mix and a whole lot cheaper.

[tam91]

Pricewise, I think you're making out even better than you think. Most of the bags of stuff at the big box stores are only .75 cubic foot as I remember.

[sprtsguy76]

Bark fines in my experience will not use up alot of N, as long as they are aged just a bit. I only use three ingredients in my container soils, fir bark fines, peat and perlite (and some lime and a complete fert). In a ratio of 5-1-1 respectively. It Drains fast and holds just the right amount of water. I love this mix!

Damon

[tam91]

So far I haven't found a source for bulk bark fines. So I seem to be back to my original mixture, since it's worked ok for me before (topsoil, composted horse manure, and peat). It seemed to hold the water fairly well, and I didn't have a problem with drainage (I use an 18 gal container per plant).

But I have to get the soil from one source, and the horse manure from another, and I'm trying to avoid paying 2 delivery charges. So I'm considering another couple of options:

1. topsoil + mushroom compost + peat
2. mushroom compost + peat
3. composted horse manure + peat

I think I've been hearing that the horse manure is better than the mushroom compost.

I've also seen info of growing tomato plants in just a bag of manure/compost - so I'm thinking perhaps the topsoil isn't bringing much to the party, and I should just eliminate it.

Any thoughts?

[dice]

The topsoil probably provides trace minerals (calcium, sulfur,
magnesium, iron, manganese, boron, molybdenum, etc), in
forms that are already available to plant roots. If you are going
to do without it, you may need to add some other sources of
minerals, depending on what you use for fertilizer.

[feldon30]

I'm a firm believer in using *some* compost in containers. I realize this is a somewhat controversial belief.

[tam91]

Ah, so we're saying the trace minerals in the topsoil would be missing in the manure or mushroom compost?

[feldon30]

My experience with most "topsoil" is it's dirt that has been scraped off a lot, with no redeeming qualities whatsoever. There is no legal definition. Of course your mileage may vary.

[tam91]

Waaah, no one agrees

Need topsoil for minerals / topsoil useless
Mushroom compost better than manure
Manure better than mushroom compost
aaak

[fortyonenorth]

Given the choice, I'd opt for #3, assuming it is, indeed, well-rotted horse manure. Without the fines, though, you really should add something to improve the drainage, e.g. perlite.

In terms of the bark fines, you might try K-Mart - my local store carried PBF last year. I've also seen it at Menard's and Home Depot, but I imagine you've checked those options.

[tam91]

I'm sure I can find the bark fines - it's paying for enough to do 30 containers worth...

The thing is (and I don't mean to be obstinate here) - with my topsoil/manure/peat combo, I'd water the plants, the water would drain out the bottom holes, and it'd stay moist enough until the next morning. So it didn't seem like there was any problem with drainage - at least not that I figured out.

Is there something I'm missing? What would be the sign of inadequate drainage, and the need for bark fines/etc?

I'm not saying I'm right or anything - everyone seems to think it would be a problem. Which I accept - except my plants grew fine. How would I know? Wilting? Lower production? ....?

[fortyonenorth]

A more porous mixture will provide better drainage and also more airspace for root development. If the heavier mix works for you, it's hard to argue with success. Maybe pickup a bag of bark fines and a small bag of perlite and mix-up just one of your containers to be lighter - then you can compare them side-by-side.

[dice]

A scientific description of optimum container media makeup
in terms of water-holding capacity vs air space:
http://edis.ifas.ufl.edu/cn004

Figure that composted horse manure is compost, with a little
higher than average N-P-K for compost (it has had plenty of
nitrogen from the beginning, with only small amounts of
high-carbon material like shavings or straw in with it). Peat and
composted horse manure would make a nicely aerated,
well-draining mix for the first summer. After that, the horse
manure will turn to silt as bacteria break it down more
completely. Silt is too fine to be useful in a container. It fills
air spaces that the plant needs.

Composted horse manure has some minerals, but it typically has little calcium in particular. and it may be low in iron and
magnesium as well (depending on the diet of the horses).
The mineral content of peat moss is so low as to be insignificant.

Bark fines take some years to break down, so they preserve air
space and drainage longer than compost. Peat moss takes about
5 years to break down completely to silt, which is why most
container mixes use a lot of it.

YMMV on topsoil. Some of it is excellent soil excavated from
bottomland along rivers and creeks, basically sandy loam,
with a fair amount of organic matter from annual additions
of leaves and dead weeds and grasses rotting on top of it.
It grows vegetables well all on its own in gardens, raised beds,
etc, with just annual additions of N-P-K to replace what gets
used up by crops and washed away by rain. Mixing in or
mulching with more organic matter each year (leaves,
compost, cover crops, manures, etc) keeps it healthy and
productive.

Other "topsoils" are just as Feldon described, "fill dirt" in a bag
on a shelf at a store or in a big pile somewhere.