Plant dahlias right away. If you have kept tubers from last year, divide them now. Each one must have an eye or live bud. Mix superphosphate into the soil. Place a tuber at the bottom of a four- to six-inch hole, and stake, to avoid impaling the tuber later. Cover with an inch or two of soil, and as the plant grows add more. Label plants so that come digging time in the fall, you'll know where they are. Keep dahlias moist but not wet, and protect from slugs and snails. Balcony gardens make nice additions to living areas and can be designed to reflect the decor inside: Oriental, tropical, modern. Choose plants with foliage that will look good all year; flowering plants can be brought in for color according to season. Use a light potting mix with Sponge Rok instead of sand so that plants are easier to move. Place the heaviest pots on casters so they can be rotated; leaves, flowers and branches grow toward the sun. Gourmet cooks can use the space to grow herbs and tomatoes; hobbyists could cultivate cactus and succulents or orchids.