On Fri, 27 Jan 2006 17:09:25 -0600, Mark Anderson wrote:

This summer will be the 5th year for my rooftop container garden. Last
summer we had a pretty bad drought here in Chicago which I think
exasperated some mistakes I have been making with regards to my soil
recipes. So now looking forward to Spring I'm researching on how to build
container soils and its getting so confusing I feel like my head is about
to explode. Some say add sand for drainage but sand clogs macro and micro
pores. Other sites say you need good drainage but your containers also
need to retain water -- two completely opposite requirements. Some say
use compost in your mixture others say compost does no good and
micro-organisms in your container soil is not a good thing.

So the more I read about container soils the less I know and the now I'm
completely confused. It now amazes me how anything grew in my garden
these last 4 years because I've been doing everything wrong.

I want to keep things simple so I found this one recipe that I might use
this summer:

1 part top soil
1 part peat
1 part perlite

That seems like a lot of perlite but I suppose it helps in aeration.
There's a nursery by me that sells perlite in 3 cu. ft. bags for not that
much so that's not a big deal. But even the potting soils I see in the
stores never have this much perlite. I'm also considering using pine bark
but am a little concerned about having woody stuff in the soil. I thought
wood leeches nitrogen. Last summer I used building sand in my soil mix
and apparently that was a *big* mistake. Although I had a good pepper and
cuke crop, my tomatoes didn't do so well even though I watered them every
day.

Does anyone have good (hopefully simple) recipes using material that can
be purchased at Home Depot or preferably Menards?

Is it bad to use compost in the soil for veggies? I read last year that
growing tomatoes in a container requires about 1/3 compost and that's what
I used last summer but now I'm reading that using compost is not good.
Compost supposedly breaks down the soil, reduces aeration, and increases
water retention leading to root rot. I suppose everything is a tradeoff
but some of these sites use absolutes.

I'll be digging out all my containers and recycling the soil as the top
soil component in any recipe. Some sites say not to use this recycled
soil because its broken down and get fresh soil. But how can this soil,
after I break it up in the soil mixing box, be any worse than those bags
of dirt that you get from Menards? How do I know if the Menards soil
isn't broken down either?

Also if anyone has good links to soil recipes that would be good too.
Thanks for any help.

Good day Mark, Here's the recipe for potting soil out of my MG manual.

1 part garden soil (not clay)

1 part washed builder's sand, perlite or pumice

1 part peat moss

1 quart of steamed bonemeal per bushel (8 gallons) of mixture

1 pint of dolomitic lime per bushel of mixture.

When I've made this, I mixed it and stored it in a 32 gallon garbage can
with a sealing lid.
To help with moisture issues that you may have, add some form of hydrogel,
better know as soilmoist, to your high water using plants such as
your tomatos. In a perfect world, a drip irrigation system on a timer
would be best but hydrogel is a good alternative. I use a lot of the stuff
every year on my clients' hanging baskets. With out the hyrogel, the
baskets would need watering 2 or 3 times a day.

I would recommend against recycling the old soil in the containers and
re-using it in new containers. The old soil will very likely have salt
build up in it and can also contain diseases. The store bought soil
_should_ be fresh and un-used with no salt traces in it.

If you have access to a pick-up truck, I'd suggest that you go and by a
yard of fresh top soil. A yard of high quality soils cost 16 dollars
around here and is much cheaper than soil by the bag.
Good luck.

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