Heather McCain tidies up a basket of "Supertunia" trailing petunias.
The first step toward creating a lush, beautiful hanging basket is in choosing your plants. Long-trailing plants such as trailing petunias require only top planting. For short-trailing plants such as 'Tapien' purple verbena, plant on the sides of the basket as well as the top for a full-looking floral display. Purchasing healthy plants is essential. I look for plants with several stems, since they will produce prolific growth. Plants in 2-1/2-inch containers are easiest to insert through a wire frame.
Most soil mixes for hanging baskets are peat-based, and can be difficult to moisten after they dry out, so I add some loam- or humus-based potting soil, as well as kelp meal for trace elements. Baskets lose water through evaporation, so closely monitor their moisture level--in hot weather, check baskets daily. Water thoroughly but allow baskets to dry out slightly between waterings. Besides a tablespoon of slow-release fertilizer at planting, I feed trailing petunias—those of the "Supertunia," "Surfinia," or "Wave" series—every third watering with a 20-20-20 fertilizer that contains iron. These extra nutrients are needed for voluminous floral displays. In mid-July, I check to see if the slow-release beads have dissolved. If they have, I add one tablespoon more.
To assemble a hanging basket, collect the materials and follow the steps outlined below. For baskets with trailing petunias, skip Steps 3 and 6, and use only six plants.