The first plants to suffer from the heat or dry air are those in hanging containers with coconut fiber lining or sphagnum moss. The strawberries shown here, for example, wilted due to dried-out soil during a heat wave. BalconyContainerGardening.com suggests using plastic plant containers in balony gardens more than any other container (i.e. terra cotta containers) because plastic containers are lightweight, cheap and insulate the plant (i.e., lose soil moisture much slower).
Because coconut fiber lining is fibrous, moisture in the soil can escape from all sides. Hanging plants are also harder to water, which means that the balcony container gardener may skip a few days of much-needed watering, especially in the heat.
But hanging baskets are attractive, and you don't have to throw them away just because they can dry out quickly. All you need to do is plant the hanging containers differently in order to combat dry soil.
Two Planting Methods to Avoid Dry Soil
1. One option is to line the lining. Place a plastic grocery bag with holes punched in it inside the coconut lining before putting dirt inside. This way the plastic will allow for drainage (very important to prevent root rot), but it will also better protect the soil from evaporation.
2. Another, prettier option is to cut slits in the lining and plant on all sides of the container. Many people will plant bunches of strawberries on the top, sides and bottom of the plant basket, and grow strawberry plants from all angles. If you do this, plant sparsely because they will grow and fill out. This same thing can be done with flowers. If you plant in this way, the plants themselves will insulate the soil and keep moisture in.
If you have an established plant, keep them in the hanging container for the rest of the season. Water them more often (on hot days, you may have to water several times every day) to keep them in good health.