It will be extremely water retentive.

I can't imagine what the 'sound' environmental reasons for staying away from peat might be, but to each his own. There isn't that much difference between peat and compost in a container medium anyway. I think you did yourself a favor by not adding vermiculite, which would have only served to add to the water retention.

The only suggestion I have is to employ a wick until your plantings are mature enough to use water fast enough to allow air to quickly return to the soil in the lower part of the container.

Good luck, TM.

Al

Al,

Would adding some pine bark to the mix be helpful? I've done some research and gather you are a big fan. Is it true that vermiculite will actually worsen water retention?

Re: peat and environment--peat is non-renewable, is a carbon sink, and has water filtration benefits, etc etc. I actually don't know that much about it but I know it is extremely difficult to find alternatives. My experiments on the seed starting end with coconut coir were less than ideal.

Yes, making bark the largest fraction of your soil can significantly reduce water retention and improve aeration. Generally speaking, vermiculite decreases aeration and increases water retention, but if the medium is already very heavy (compost/peat/coir), the effect is less noticeable.

I wrote this about peat a while back:

Peat - Renewable or Not? - Does it Matter?

Chicken Little would be aghast at your inference!! In my estimation, it doesn't matter much if it's renewable or not, and I refuse to be made to feel guilty about using any form of peat.

Here is a reply I often leave when the renewable/non-renewable thing comes up:
"Sorry, but I'm not buying the non-renewable lament. In Canada alone, there are more than 270 million acres of harvestable peat bogs. If we make the conservative guess that the harvestable portions of these bogs are 10 feet deep, that means there are probably more than 900 billion cu. ft. available for harvest, just in Canada! That doesn't even take into consideration what's available in the US, Europe, Asia, or places like New Zealand where they also mine peat. Canada currently has mining/harvesting operations underway on approximately 40 thousand acres or about .014% (that reads 14 one thousandths of 1 percent)."

Check the math - it's accurate and conservative. It's more likely that the next ice age will be upon us and glaciers will have covered what's available before we even use a noticeable percentage.

Renewable/non-renewable = moot.

Al