may I jump in here? justaguy, are you saying that adding compost (e.g., composted cow manure) in with the potting mix is of no value? If that's what you mean, does adding composted material cause any harm in your opinion, if it does not create aeration problems? I added Black Kow (composted manure) into my containers (not SWCs) this year with potting mix. I have had my share of issues (seems like everyone has this year though!). I used organic fertilizer when originally planting, although I read here it's really of no value in containers. So now I'm confused....add compost? organic fertilizer? yes, no? Does it help, hurt or is it neutral? (One thing I have begun to suspect is that the containers with the best drainage opportunity at the bottom (the more holes of significant size) fared better. Perhaps this allows more oxygen availability to the roots? Just a hunch I have based on my experience this year with containers.)

The reason you can't trust the volume of nursery pots, Jim, is that those black nursery containers are all "nominal" sizes. That means the volume of the pots is vaguely related to the stated gallon size. A "5 galllon" nursery can is 10.5 in. diameter and 12 in. tall. My online calculator says that is only 3.75 gallons if you pot 2 inches from the top of the pot. That isn't large enough for any rose past the first year or so if it puts on vigorous growth. The foot stomping is an old landscaper practice. It's just a cheap way of determining settlement without taking the time to water a plant in. I wouldn't do it. Water your plant in to settle the soil. I've seen people planting roses into dry potting soil. I wouldn't do it. Many potting soils have peat moss which sheds water once dry. Those of you in climates with steady rain year round may not have this problem, but in the desert West, once peat dries out, it takes a concerted effort to dampen it. I open the bag of soil, stick the hose in, fill it up and mix. Then I pot with dripping wet potting soil and also water it in. It's mud pies for grownups. It assures that the soil comes to the optimal height in the pot (about 2 inches down) and fills major air pockets. I unpot roses all the time and have never found an air pocket. I don't drop pots on purpose. Our summers are too hot to grow a lot of roses in pots well. We can't keep the roots cool enough through June and July. I overpot extensively. A 3 x 3 rose goes in an ornamental pot that is 22-24 inches high. I use various decorative pots from the big box store and always buy the biggest size. Why? They bring to rose up to height and look more in scale with a landscape. It's funny how a pot looks big in a store and miniature in the garden. Also, with those big pots I'm approaching the 15 gallon actual size I find any healthy rose needs. I do a seat of the pants volume-of-cone calculation to guesstimate the volume of the pot, taking into consideration the potting soil is probably 3 inches from the top of the container. Here's a nice online volumetric calculator. http://www.online-calculators.co.uk/volumetric/conevolume.php

Hi Sarah, I'm Pam. :) I can see the advantages and disadvantages of your set up. I looked at the ingredients of the soil mix your using and it seems pretty dense to me. Quote: Contains a blend of sphagnum peat moss, compost and natural fertilizer... Sounds like a good, readily available base to start with. To me, here in the temperate rain forest, it would turn into a bog much of the year. Bog plants are nice. But... adding materials to give it more texture, so the roots have air seems the next step.I will link to the thread you want over in the container forum at the end of this post. It's a very long first post full of facts, so I suggest first scrolling through to get a feel for what's there and focusing on the relevant parts for you, right now. You may want to bookmark that one. Where I am, in a city too, I can get super large bags of pumice at an outlying farm supply store. Not sure the size of the bag, but I can't reach all the way around it and it stands up to my shoulders. One bag lasts me a couple of years. The tiny bags sold in most stores are way too expensive, so this might be something you could look around for, if you have transportation. I also use lots of 'bark mulch in my potting soil mixes. I have a gas station three blocks over that brings in medium sized fir mulch each spring/summer, so I walk my garden wagon over off and on and drag back another bag. It's funny seeing car passengers trying to figure out what that old lady is up to. When I bring a bag of manure home on the bus, in my granny cart, it seems better to wrap it in a plain black garbage bag. What they don't know, won't hurt them. LOL. My point being we each find sources that work for the individual. I like the idea of the boxes on the concrete, since it' will be easy to keep the children clean and not tracking stuff in, plus it's small enough you can keep track of things pretty easy and not get discouraged. I'm wondering how it is going to hold moisture in the heat, and how the heat will affect the center and the edges differently. A great garden experiment. I bet the heat loving herbs will thrive in just the right spot. All that extra heat from the concrete will be just heaven to them. My first idea for the plants like a tomato that wants deeper soil. What about adding some bottomless boxes. That could look really nice. Carefully arranged to look good from the window, but with the taller things not shading the other plants nearby. Yeah, this is where you move things around a few times.Any deeper container will work. I'm picturing the tomato roots going down through the container and then spreading out to where ever in the bigger 4X4 box it finds suits it needs. I wonder if somebody on http://pinterest.com/# has done something like this, it could look so interesting. You have a good base to build on. Two budget tips, since this garden thing doesn't get built in a season, would be 1. at the end of the season some places that only sell soil amendments part of the year, put it all on sale. That's a great time to stock up and have ready for next year. And 2. This is the time of year many counties run composting workshops, and also sell smaller plastic bins at a greatly reduced price. The one sold here is the Earth Machine. It's a nice way to start out. Doing a spring clean up around the area may give you some older fall leaves, then add the weeds and some kitchen compost, and your on your way to having more to add next year. My other two thoughts are you may find once it gets hot, it's drying out too fast. Adding a mulch will help, plus be adding for next years total. As far as next year. I don't have a crystal ball, but I'm imaging these boxes going higher, building the same box shape, just adding it on top. Doing it all at the start is just too much expense. I'm so curious how this is going to work where you are. What fun ! Here is a link that might be useful: The promised link

Hi Ricker, Welcome. This forum (LA/MS) hasn't been very active lately. You might ask your question on vegetable forum, or container gardening too. I think it is easiest to buy potting soil (not garden or top soil) for your containers. Some of them have a slow release fertilizer already added, some have moisture crystals which help the soil retain water. I did find this online "Tom MacCubbin, gardening expert and author of several great books recommends this mixture: 2 quarts sphagnum peat moss, 2 quarts horticultural vermiculite, 1/2 tablespoon dolomitic lime. This mix works for both seeds and transplants." I can't vouch for MacCubbin, don't know that author. Also thought you might like to know about this website, if you don't already, msucares.com which is the Mississippi State ag/home gardening website. Also you can find your county's master gardeners if you google them. They usually have a hotline type service where you call with questions, they sent you alot of free info too, on all kinds of garden topics. Laurie