Oh ... don't put rocks in the raised bed. There is absolutely no benefit to be had from doing that. Yes, that will take a lot of soil to fill. However you can get it cheaply (compared to bagged prices) by the cubic yard, delivered. A 4x10 bed that is "thigh high" - what is thigh high? About 24"? Or more like 30"? Assume that it is 24". So that is 4x10x2, which is about 3 cu yards, for one bed. Of course you don't want to fill it all the way to the top but that's a ballpark figure. For 2 beds, obviously, that's about 6 cu yards needed. You want clean screened topsoil. You should have someone knowledgable about garden soils inspect it before you buy and have it delivered to make sure it is satisfactory. It should cost in the area of $15 (give or take a few bucks) per cubic YARD (not cubic foot). There is usually a delivery charge, but they usually won't charge that if you are getting 10 cu yards or more delivered. Maybe your scout leader could negotiate a remittance or reduction of the delivery fee since its for a senior center. Or maybe you could build an extra bed! And use some of the dirt to beef up their ornamentals or flower beds! I doubt there is anyway to back a dump truck up to the beds themselves so you will need a spot where it can be dumped, and you young strong Eagle Scouts should start trucking the dirt over to the raised beds in wheelbarrows. If the raised bed is 2' or more high, a small moveable ramp (can be made from wood scraps) might be helpful in getting the front of the wheelbarrow high enough up to dump over the lip. 6 eagles scouts armed with one shovel apiece and 3 wheelbarrows should make short work of the process. One eagle scout on either side of the wheelbarrow to dump it. Keep moving the wheelbarrow down the line to dump the soil. There should be room to dump from either side. So, Dump on one side, then Dump on the other, then move down the line. This way you won't have to spread it as much. As to the raised beds. Although 4' widths are typical for raised beds, older folks and shorter folks (such as myself, who woke up one morning to discover I was now a member of both categories) have difficulty reaching that far in. Consider making them 3' wide instead. And then consider making 3 beds to make up for the loss of growing space. It depends on how much space they have. Be sure to leave PLENTY of space in pathways between the beds and anything else nearby to allow for the passage of wheel chairs, walkers, and rolling garden scooters and carts. I suggest 4' minimum clearance per side if possible so people can always get around each other. 5' or even 6' would probably be better. Not to be indelicate, but ... human beings who have reached an advanced age sometimes find themselves in a situation where any impedance in getting to a bathroom could result in a humiliating experience. Among other things. There are a LOT of reasons to make sure there is plenty of space to move around. Safety considerations, for example. The less chance of someone taking a tumble because access pathways are crowded, the better. At your age, tripping and falling down results in maybe a skinned knee and possibly some embarrassment at your own clumsiness; at my age, it could result in a broken hip and a long slow (or not so slow) decline to the end. You absolutely CAN use modern pressure treated wood to construct raised beds. The new stuff does not leach like the old stuff, and the old stuff didn't leach that much until it was itself fairly advanced in years. The old stuff was treated with arsenic and that is mostly what could leach into the soil. However, unless your plants are significantly deficient in (I think) potassium? or phosphorus?, they don't take up arsenic, so the risk was always pretty minimal. With the new stuff, there is no arsenic. The only thing that leaches into the soil is a very small amount of copper. Copper is actually a dietary requirement (in small amounts). And again, plants take up little or no copper and it takes decades for this leaching process to take place. Organic standards STILL don't allow for the use of any pressure treated woods, but outside of knee-jerk reactions to PERCEIVED risk (as opposed to ACTUAL risk) there is no reason for concern over the use of modern pressure treated woods in your veggie garden. You can read more about it here and decide for yourself. You could use cement blocks to build the beds instead, which has the added advantage of having a space to sit while working on the bed. Top it with flat pavers or wood for a comfortable ledge upon which the gardener may perch while he or she is at work. It has the advantage of being permanent and sturdy, but the disadvantage of expense. Building up walls that high takes a lotta concrete blocks. It also may winter-heave over time. Depends on your climate. But honestly the easiest thing to do is just build them out of pressure treated wood. The modern stuff is safe for this use. You could build some elevated beds as well. Those would need to be a little higher off the ground - "waist" height (whatever that means) but because they are so high off the ground, crops such as tomatoes could not easily be grown in them. But shorter crops such as peppers and eggplants, cabbage, lettuce, etc. The beds would be more susceptible to drying out than a bed at ground level. If there is time and funding enough, consider installing a drip irrigation system for the beds. Not the expensive underground computer controlled type, but the affordable home gardener type that uses rubber hoses and emitters. Look for Orbit or Rainbird systems. Again some help from a knowledgable gardener would be useful. Contact your local extension agency and ask for help from one of their Master Gardeners or an extension agent. Using quick disconnects (get solid brass fittings so the oldsters don't have to deal with equipment breakdown in a year or two) you can easily set up a permanently installed system that doesn't have exposed hoses for people to trip over 24/7. Just haul a hose out and plug it in when you're watering and then disconnect, coil up and store the main supply hose when its not in use. Everything else will be mounted in the beds where nobody will ever walk. Encourage the use of mulch to cut down on evaporative loss and discourage weeds. In my raised beds, I actually lay down wetted flattened brown corrugated carbon boxes and plant through that, then cover over all with bark mulch. You want undyed 100% wood with no demolition content. This may also be purchased for less than bagged prices if you buy it by the cu yard. Again there are delivery charges etc etc. But a lot of municipalities collect yard waste and grind it up and make it available for little or no cost to city residents. Contact your city and perhaps your leader can negotiate a free or low cost delivery of last year's ground up tree limbs to be used as mulch in these raised beds. Or get some dads with trucks. Remember to leave room for the mulch layer when filling your beds. Also keep in mind that the soil you add to the beds WILL SETTLE. So its a balancing act. Don't order the dirt until the builds are completed and you have volunteers who will definitely show up to move it. Make sure the senior center will have a spot to dump the fill dirt, and that you have sufficient manpower to get it moved in a timely fashion. Be prepared to clean up any construction mess. It's more complicated to talk about it than to actually do it. Here is a link that might be useful: calculator for cubic yards needed

Hello. You didn't say whether this is a new home for you. I spent the first year checking out the sunshine in our backyard. My backyard was a south facing yard. The back fence shaded the back yard almost 4 feet into the yard. Which meant I started my first cinder block line just over 4 feet away from the block fence. OR the winter garden would never get any sun. During the summer time, the block fence might radiate too much heat back off the fence. My cinder block garden was 3 cinder blocks tall. 24 inches interior width. I started with 1 brick high. I found the roots didn't have enough room. So I went up to 2 bricks. Again, not tall enough for tomato plants if you bury your seedlings deep like many recommend. So, I went up to 3 bricks high. Perfect for me. I agree with previous posters. If you make the garden too wide, you won't be able to reach all sides of the garden. Important when you are trying to find the peas within the vines, tomatoes under their leaves, or to pull radishes that are ready for your salad. I put the blocks right on the hard AZ soil. I then added mulch, mulch, soil, manure, mulch, manure.... It took almost 3 years to get the perfectly blended soil for all sorts of vege's. Shoveling, raking, and spreading more manure did the trick. I mulched all my kitchen scraps I could. That certainly helped with the health of the soil. Oh by the way, the soil won't bulge out or push the bricks away. At least in my case. Any extra water leaked between some of the cracks and down to the bottom of the bricks. Making sure you have enough water to absorb into the soil so your plants have a chance to drink before it runs out at the bottom. Good luck!!

We have an organic source of compost from our local dump. I usually get a truckload about every other year and use as much of my own compost as I can. I have started letting one bed go unplanted each year and composting straight on the bed in a bin. There's still room to plant something small like basil while the box sits there in the middle. About every 3rd year, I buy a load of "garden mix" from the organic dump place and top it off. I have a very small tiller that I mix it all in with (only about 10 lbs) Truckloads are really the way to go. With 20 forever beds, you can always find a place for the soil/compost! Nancy

I just did a green manure over winter and then double dug the mass of Austrian peas and crownvetch deep into the bed this spring right before planting. They told me to wait 2 weeks but I didn't because I was already late. I figured it would be two weeks before any roots got down there.. GOD, everything is loving it. It could be all the rain too. I have never seen green beans so happy or cucumbers so quick out of the gate and fruiting so quickly too.. I will be doing green manure to half my garden next year. I missed having my winter garden last year. About the draining water. My raised beds are big enough and high enough so I plant in ditches around tomatoes and build hollows around my cages of beans. Everything gets a bit of a ditch in the summertime. When I water the ditches and walls direct the water to the roots. It does not spread out. I learned that from someone who gardens in New Mexico. I have been thinking of using some ollahs too as an experiment. There are ways to make them with clay pots and a plastic gallon jug with holes in the bottom variation.