Dear Rose,
Try using the warm or even hot water method and put in a tough plastic bag. Use trash can size clear ones if you can find them. You don't have to get your hands dirty this way, you just put the medium and water in the bag, close it with a twist tie and roll the bag around to distribute the water. The advantage of the clear bag is that you can see the mixture and see if you have added enough water. Once everything has gotten damp, you can keep it moist for a long time. I try to only make up as much as I can use in a week or so. Works great for me!
Ginny (PA-Z6)