raised bed potting soil mix need something else mixed in?

[marykay]

This is our first try at a desert garden. We live in South West Arizona.We built 2 -2'x16' raised beds on hardware cloth. We filled the boxes with Kellogg Patio Plus potting soil per suggestion from Home Depot Gardener. We have a soaker hose to each bed run on a timer. The water seeps down and covers about 15 feet around the beds. Clearly there is drainage. I planted a few seeds at one end of one bed( which I am willing to start over if need be). My question is do I need to mix something else with the potting soil because of the water going to the bottom and the rest is dry? I would appreciate any input.
Thank You

[2cents]

if you pack some clay around the outside of the bed(wood frame?). There will be less moisture loss.

[jal_ut]

What you need is some fines to hold the moisture better. Do you get any of that "blow sand" down there? That is pretty fine and may be just what you need, and cheap.

[Dillbert]

here's what the MSDS says:
"
This product contains no hazardous ingredients as defined by
the OSHA Hazard Communication Standard in concentration
greater than 0.1%. Kellogg Patio Plus is a proprietary
formulation of organic bulking agents. It contains fir bark,
worm castings, perlite, chicken manure, bat guano, kelp meal,
oyster shell and dolomite lime (pH adjusters).
"

perhaps it's going to take a little time for the organics to "soak / swell up" ?
sounds like the water is just "running through" -

I suspected it might contain peat - which is "water adverse" out-of-the-bag - but I've not experienced that problem with bark products.

[Dillbert]

oops, did a double....

[rainbowgardener]

They purposely make potting soil light and well draining for use in containers. For raised beds, I would mix it up to half and half with good garden topsoil and/or compost.

[ruggr10]

I experimented in the fall and made one totally full and layers of composted horse poo.

It went (from bottom to top) compost, seaweed, compost, leaves, compost, seaweed.

Normally I purchased loam by the yard but I think putting this in during the fall will make some plants very happy come spring.

[Bobberman]

I would also mix strained top soil in with the mix but first before you plant anything I would soak the bed! Potting soil tends to have water run off without soaking in so it stays dry! Soak everything so its very wet then it will retain moisture much easier!
+++
I myself would have mixed top soil in with the potting soil for the bottom layer and have a 2 inch potting soil only at the top! what this does is keep some of the weeds down. Another idea is find a area of good top soil and take the first 6 inh layer off and only use the bottom next foot of top soil. Less weeds this way but I would strain every bit of garden soil.
+++
If you have any leaves put a layer at the bottom of your raised beds and maybe sprinkle some blood meal or cottonseed meal over the leaves at least a foot below the surface! The leaves will keep moisture in the bed and the nitrogen from the meal will add a small amount of heat to the bed as the leaves decay!

[estorms]

I once put a bag of peat moss in a large hole with a bag of cow manure and some regular dirt. All the water went right to the bottom without getting the top wet. Now I fill the wheelbarrow with my soil mixture and wet it with a pail of water with a tablespoon of dish detergent. If it doesn't get wet, wait overnight and mix it up again in the morning.

[dustyrivergardens]

forty percent compost ten percent rock dust twenty five percent peat moss 25 percent vermiculite. always works for me in containers raised beds what ever. water well and stir till done. lol

[estorms]

I am not using anything with "rock" in it's name. We have so many rocks here that when I want to plant something, I scrape the grass off, dig out rocks until I have a nice hole, then bring in dirt to plant my shrub. I definitely have more rocks than dirt. The person I bought the place from had fake rocks around her flowerbeds.

[ruggr10]

Rock dust like azomite contains many of the minerals that plants need, just like people need.

[rainbowgardener]

I am not using anything with "rock" in it's name. We have so many rocks here that when I want to plant something, I scrape the grass off, dig out rocks until I have a nice hole, then bring in dirt to plant my shrub. I definitely have more rocks than dirt. The person I bought the place from had fake rocks around her flowerbeds.

Weird! Whyever would you buy fake rocks, when you have so many real ones?

But I understand about not having any actual dirt. Mine is a little bit less rocky, but what I have instead of some of the rocks is pure solid clay, like you could make pottery out of. When I built raised beds, I had topsoil trucked in, because there was no where I could just dig up dirt to fill them.

[estorms]

I did the same thing last summer. I found some landscaping timbers behind my shed and made a raised bed. One pick up load of topsoil just filled it. Unfortunately, the top soil was creek bed soil. No nutrients. I added some after it was apparent my carrots weren't doing well, but it was too late. Then a deer came in the night and finished them off. This year I will add some compost and fertilizer and put chicken wire over it. That should take care of it.