In the case of short absences during the summer, giving plants a thorough watering before going away may be sufficient. Moving them to a cooler room or away from a bright window will help prevent them drying out.
For longer absences special measures can be taken to prevent the plant suffering or dying. These are based on providing a reservoir of water for the plant to draw on:
This method is useful for large single pot plants. Use a large container to hold water, and a piece of capillary matting as a wick. Insert one end of the wick into the reservoir and tuck the other end into the plant pot. This will enable the plant to draw on the water reserves in the reservoir.
Use this method for collections of smaller pot plants. It may not work with pots that have broken crocks in the bottom.
Place a sheet of capillary matting on the kitchen sink draining board or a suitable surface next to the bath. Drape one end of the matting into the sink or bath, which is filled with water. Plants should be grouped on the wet matting, ensuring they make good contact with it by pressing them down slightly. Clay pots need a thorough watering first for them to start drawing up water from the mat.
Covering plants with a clear plastic bag
Use this method for short-term absences only. Place a clear plastic bag over your plant and seal it closed. This allows water vapour to be collected and recycled by the plant. Keep the sides of the bag out of contact with the plant by supporting the bag with canes.
These containers have built-in reservoir systems. They are best suited to plants that need moisture year-round and do not mind being grown permanently in moist conditions. Plants such as Citrus (which need less water in winter than in summer) are less suited to such permanent growing systems. Plants can be temporarily re-potted into reservoir pots if desired.