A raised bed is not always the solution. If a yard is wet for long periods then it is probability prudent to put drainage tiles in place. A wet yard with poor drainage and a raised bed only means that the raised beds will be wet, due to wick effect. My yard was a bog six years ago. I put in about 300 feet of tile and ran the water to the city storm sewers. Now the surface water is gone. My yard is basically dry. The raised beds are convenient to contain the area, since it gets sort of sloppy on the edges if not fenced in. The drainage was a trench 18 inches deep and 12 inches wide, Gravel in the bottom, five inch plastic weeping tile, gravel on top, and some soil added, and the sod returned to improve the appearance. The work was dug by hand in 2003 all by myself. Also drainage tiles will not work if the top layer is at hardpan level. There must be some drainage into the ground. The backfill in my yard was done properly in that there is about two feet of good clay backfill before hitting hardpan. Some contractors sell the top soil when building, and simply lay sod onto the hardpan. The yard will always be soggy no matter what steps are taken in his case. This can be improved only by adding about two feet of reasonable soil, and then adding the drainage ditches.. The point is: Before installing raised beds, and applying drainage techniques, insure that you know what you are working with.
