Why do you say that you doubt it will dry out? Is it a wet or low lying area or a flood plain or a swampy muddy area? If so, you will have better results in an area that does dry out between rains or between waterings. If it stays wet / moist all the time they will not thrive. Also, no matter how good or bad the soil is, you will get better results by adding some organic amendments like quality compost of some kind. PH should be OK