Maintenance of container grown Olive or Bay trees:
To stop your tree looking tired or dying, it is wise to remove the tree from the container in November-December on a day when the root system is not frozen to stop thermal frosting of the root system. Cut away ten per cent of the root system from all around the root system.
Then, using a mix of 50% good quality potting compost and 50% topsoil, mixed together well, add to the bottom of the container with a slow release fertiliser. Put the tree back into the container and fill around the sides. Doing this every year or every other year, will encourage a stronger, healthier root system. This in turn will help the tree to withstand any fungal attack at the roots, as well as the foliage. Feeding over the roots in a container should happen between March to September. We do sell the ideal fertiliser to use. Pruning the head of the tree into your desired shape can be throughout the year on that year’s growth.
If pruning harder into thicker growth we would recommend leaving this until November- December. Thicker wood will bleed during the growing season. This can encourage insects that will feed from the sap. The insect could have been on a diseased tree beforehand and with an open wound, the likelihood of infection is greater. In the winter, the sap cycle is reduced massively and most insects are hibernating. Therefore, in our opinion there is less risk of infection.