Hi, Christine! I'm glad you recognized the utility in the concept most of us so enjoy sharing.

First - I don't think you're in over your head at all. You recognize a common problem that occurs with water-retentive soils and are setting about trying to fix it. There are a couple of thinks you can do. One, of course, is to amend the MG soil with lots of pine bark and some perlite. I can tell you that perlite is going to me more valuable than pine bark unless you make pine bark the primary fraction of the soil. The reason is, neither pine bark or perlite have a significant impact on the flow-through rate (drainage) of the soil or the ht of the perched water table (PWT) unless and until, combined, they become the most significant fraction of the soil. Perlite though, is not internally porous like pine bark, so it works better at reducing water retention.
So, if you're going to go all the way and add a LOT of pine bark and some perlite, you'll be reducing water retention via the route of increased aeration. If you only intend to add 'some' pine bark and perlite, skip the pine bark and go with the perlite because that route doesn't reduce water-retention via increased aeration, it reduces water retention because the perlite, which doesn't hold water internally, will be 'taking up space' that would normally be occupied by water.

Obviously, it's to every one's (yours and your plants')advantage to go the route of reduced water retention due to increased aeration, but I'll leave you to your own decision. ;o)

If the gaps between the slats are covered by insect screen, you should be fine. Some fine particles will filter through, but that's actually to your advantage.

If you stick with the MG soil, I might even suggest that you make some nice even loops of screen that hang down below the slats in a few places. I say this because it will help you a LOT with any PWT woes you might encounter. Water will always 'look' for the deepest part of the container, If you have a couple of loops hanging below the slats, the water from the upper part of the soil will move into the loop. Illustration: Lets say the MG soil supports 4" of perched water (about right). If you engineer a loop or two that hangs 2" below the bottom of the slats, you have that 2" of soil plus the thickness of the slats, so lets say you have an extra, thin line of soil in that loop that is 2 + 3/4" deep, or 2-3/4" deep. That will LOWER the PWT in the soil above the slats that would normally have been 2" deep to 1-1/4" deep. Something MUCH easier to deal with. Now, you're 'outwitting' the soil by using the soil itself as a wick. Do you follow me here? I'm only asking because you said you were new. ;-) I can help you to do the same thing with a flange and a tailpiece, too. I was just helping a guy ovr on the organic forum - you might find reading the thread helpful. See below, and let me know what else I can help with. ;o)

Al

Here is a link that might be useful: Click me and I'll take you right to what he was talking about.

I agree with Christine, sometimes I feel like I'm in over my head with my vegie garden. I only have a deck so everything is planted in containers..so I'm not much help with the raised bed.

I found a really neat product that made all my vegies and flowers grow like crazy! Check out the Plant Warrior and Holey Cone, it helps aerate the root systems and I didn't have to do anything different. ~Shonya

Plenty of people here to toss you guys feeling 'in over your heads' a life ring. ;-)

Al

Thanks, Al! Well I'd like to go with mostly pine bark, but that will depend on what I can find. I'd be going with partially composted?

If I end up having to go just perlite, and thus there's more fine soil, do I ever risk having the screen clog up and prevent water from draining? Would putting in a layer of coarse bark be beneficial, or since that's essentially a drainage layer, no?

I told my husband about the loops, and we went back out to look at our work in progress, but we're just not sure about it. With the weight of the soil hanging down, he feels it could cause weakness in the screen. Although now that I've typed that, I would think the weight of the soil on the screen that's not lower would help support the loops.

I think I'm at the point where I need to just DO. Gardening carries with it a lot of trial and error after all, right?

Please say yes. ;-)

And Shonya, I checked those out. I actually have one container that's a lot like those, just with a shorter cone part. I'll have to pay special attention to whatever I put in there to see if it does better than the same plant in a different container.

Oh, one more thing. Does anyone actually seed in the 5:1:1 or gritty mix? I've got some seed starter mix as I was going to do some seeds weeks ago inside, but didn't. Is there a certain mix I should do on the top layer to get the seeds going or just keep it all the same?

I don't think you'd ever need to worry about the screen clogging. It will be fine ..... and I'd skip the coarse layer of bark on the bottom - it won't do any good. ;o)

About the loops - I don't see any problem with the screen sagging or shifting, but if you're worried and DO want to use that suggestion, just a few staples are all that would be needed to hold it securely in place - just an idea for you guys to kick around. ;o)

Actually, some people would have you believe that trial and error is a good way to learn, but it's not. It's very slow and there are those ERRORS that are expensive in more ways than one. If you learn the reasons behind why things work best in certain ways, you go into a project knowing what to do and what to expect. That way, you let your experiences validate your knowledge. This is extremely helpful because it's always better to question your own precepts when they don't agree with science than to make up science to fit your precepts. IOW - if your observations don't match what you know to be true, question the validity of your observations. I do that all the time. I tell myself I WANT to think it's THIS, but I know it can't be this because ....... then I start looking for what the real answer is. I ALWAYS doubt myself before I doubt science - keeps me honest and I spend a LOT less time spinning my wheels. ;o)

I've started lots of seeds & cuttings in both mixes. It's always better to use a sterile medium for both, but I've never really run into any trouble with damping off or excess water retention. I start a lot of tree seeds (oh darn - I have something I need to do .... fast) on top of the gritty mix, then covered with Turface fines. You could do the same, or start on top of the 5:1:1 mix and cover with a little screened peat (1/4"). Mist carefully to water - think 'damp', not 'wet'.

Al

Well when you put it that way, Al. ;-)

The box should be done tonight, so as long as I can find what I need this afternoon, everything will hopefully be done by the end of the weekend.

Please don't take from what I said that I'm trying to change your mind or influence your decision. That's not it at all. ;o) I'm just fond of pointing out that trial & succeed is to be much preferred to trial & error. I'll help any way I can, no matter how you go forward. Got it!? ;o)

Al