tree trunks need air.. if buried.. they will rot and kill the tree ... they can NOT cope with constant moisture ... with me so far ... in contrast.. roots need near constant coolness and moisture .. which we call soil ... once 'established' ... they can take care of all that ... so ... take your blocks... make a 6 to 9 foot circle ... bring in top soil that nearly matches you native soil ... and plant the tree .. so the root/trunk interface is at the level of the second bricks ... we do NOT use potting media or foo foo soils for backfill, especially with trees ... regardless... it will need to be staked for a year.. to get some roots down.. until the soil settles ... if you have clay soil.. advise and i will change the method ... perhaps .... you would be better off.. getting native soil from behind the garage.. and using that.. than bringing in mismatching soil ... if you were wanting to put in a perennial garden.. you would be better off.. stealing the native soil for the tree.. and bringing in a good soil for that bed ... its getting a bit late for planting trees.. unless you have a warranty .... where are you ... ken

At my last house I had raised beds - 4' wide by 12-20' long with wooden sides about 1 1/2 foot tall. Over two or three years we built 8 of these large beds plus several smaller beds for perennial crops like stawberries, rhubarb, and horseradish. For that situation, there were several advantages. It allowed us to have flat areas on a hill; we terraced with rock walls and put the beds on those flat areas, surrounded by woodchips for mulch, so there was no weeding at all. The beds were sunk about a foot below the grade, and we had to sift the soil, which was shallow over fractured ledge, to get rid of all the rock, and then we filled the rest of the beds with composted cow manure, thanks to our local dairy farmer. So, we ended up with no weeds & great soil in flat beds from an area that started out mostly rock on a steep grade. Other pluses were sitting on the bed sides to plant, screwing trellises for beans, melons, cukes, etc. directly into the bed sides, and the ablility to plant early due to good drainage and early season warm-up. We also sometimes put plastic hoops over the beds, tucking the hoop ends inside the beds to hold them, to cover with spun-bond or plastic. On our strawberry beds, we put hinged wire mesh covers so the chipmunks couldn't eat the berries. Between mulch and the high organic content of the soil, we only had to water when it had been dry for a couple of weeks or more. Our current house had a pre-existing ground-level garden which we simply took over as was since the house needed a huge amount of work, so that's where our efforts and energy went. I miss the raised beds, and find that I have more difficulty with soil-living bugs like wire worms in my potatoes and cutworms crawling in from the surrounding field. I can't work in the garden as long since I have to bend more or sit on & scoot along the ground. (I'm no spring chicken!) The grass and weeds migrate into the veggie garden from the surrounding field, and the soil needs to be prepped in the fall so I can plant peas, potatoes, etc. earlier in spring since the soil stays cold and wet for much longer. There are two only advantages I can see to the ground level garden: it's easier to till with a machine like a big tiller or tractor if you want to be able to do that, and any crops that need winter warmth can be well mulched and will stay warmer in the ground. Garlic, which is a bit borderline as far as hardiness here, has better survival rates, and my leeks and root vegetables overwinter better with a thick layer of mulch when they are in the ground rather than in a raised bed. So, like Lisa, I will eventually have some of both, but with most of my garden as raised beds and a smaller part of it in the ground.

well I am no expert at growing in Phoenix but I like having raised beds. You probably want them at least 8" high and no wider than 4', that way you can weed and pick without walking in the bed. The tomatoes and beans will probably need to be staked or supported in some way. You need to install those supports when you plant them. I put down weed barrier between the beds. I have lots of river rock in my soil and as I remove it, I put it on the weed barrier, makes nice pathways. Good luck!

I would start with soil first leaves should be shredded and left to leach and decompose for 4-6 months for the best results then you can use as a top dressing or mulch you can also till it in for the organic matter ( the worms love it) . I start out with a 10x10x10 leaf pile ( shredded) and it shrinks to 1/2 that by spring by then it's ready for any garden use but no matter what you should shred them before using them in the garden. Back to the raised beds not sure how big they are and what kind of budget you have. I would start with some peat moss mixed with some top soil add some dried manure I would look for local stables you might get it just for hauling it off make sure it's older stuff . I take my grandson and we go to a friends cow pasture and fill about 10 5gal buckets with dried patties after we do that several times I run them through my chipper then I mix that into my beds works great. You can also buy composted manure mix the peat moss , top soil and manure add a few shredded leaves if you like and it should work great. If you have a lawn and a bagger for your mower try using the clippings as mulch around your plants its all I use it's like adding manure as you grow it doesn't burn or hurt your plants as some would profess I've done it for 40 yrs put it on thick 6-12 inches it decomposes fast.