If you won’t be able to water your plants for awhile, the ice cube hack helps, but the cold can stress the plant and damage the leaves. Try a different approach. Bury one end of thick cotton yarn into the soil and place the other end into a glass, bowl or pot of water. (Be sure the yarn goes to the bottom of the glass). Your plant will soak in as much water as it needs. You can arrange this to water several at a time.