Place a sponge in the bottom of a planter before adding soil, to keep water in reserve. Really makes a difference in window boxes!
Plant pot too heavy? Buy a bag of foam packing peanuts (available at office supply stores). Fill the pot one-third to one-half full of peanuts, cover with landscape fabric and then add soil. This cuts the weight and saves money, since peanuts cost less than good potting soil. However, a smaller amount of soil means more frequent watering. To slow evaporation, cover the soil with wood mulch.