CONTAINERS FOR SHRUBS
2 April 2008 Where would we be without plant containers. They are available in a range of materials and include wood, metal, plastic, earthenware, ceramic and wire mesh.
Shapes vary from traditional pot shapes to wooden barrels and Versailles boxes. There are square and rectangular ones but a word of caution, the lovely curved, earthenware containers with the shoulders are a disaster for long term plants.
 If the “waist” is wider than the “neck” then when the plant needs to be re-potted it is impossible to get the ball of roots out without breaking the pot.
Metal containers such as stainless steel, zinc coated and beaten alloy have become popular but they can be deadly for plants. In summer the sun heats the metal scorching the plant roots while in winter the metal sheet may become sufficiently cold as to kill young roots.
There must be an adequate drainage outlet at the base of the pot and  the holes should be checked on a regular basis to make sure they are not blocked. Standing the container on “feet” will allow water to drain away and prevent wood lice and ants crawling up through the drainage holes. If the feet are smeared with Vaseline it is an effective deterrent for slugs and snails.
 Wherever possible use a soil based compost for shrubs. It will make watering easier to control and prevent the compost drying out. It will have some trace elements and retain the main nutrients for longer. Although it is heavier than soilless compost, making moving the containers more difficuly, its weight will reduce the risk of the pot blowing over and breaking.
Cover the drainage holes with either pieces of broken clay pots or pieces of polystyrene. These are light and stop the compost blocking the drainage hole.
Always plant the shrub at the same depth as previously grown. The surface of the compost should be at least 5-7 cm below the pot rim. This will assist with watering and allow for a top up of fresh compost next year. A decorative layer of round pebbles, glass beads or gravel will finish the job.
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