Olive trees grow naturally in the warm Mediterranean, though people cultivate them in other parts of the world as well. Olive trees are one of the oldest cultivated trees in existence, and they grow well in many soil conditions. UK gardeners who want to grow their own potted olive trees in a conservatory, greenhouse or sheltered sunny spot in the garden should choose the right fertiliser for optimal fruit health.
Olive trees grow best in long, hot summers and cold winters. A late spring frost may kill the flower blossoms before they produce olives. Temperatures below -2C will damage the fruit, so in the UK you will need to bring potted olive trees inside for the winter. Plant olive trees in well-drained soil where they will receive full sunlight, six hours or more a day. Upon planting the tree in a new container do not add fertiliser or other organic material in an effort to improve soil quality. Use only native soil when planting.
When to fertilise
After planting the tree, wait until the beginning of the growing season -- March -- to fertilise. Only apply fast-release nitrogen fertiliser treatments infrequently; once or twice a year at most. You may use small doses of slow-release fertiliser throughout the spring growing season, once a month in March, April, May and June.
Types of fertiliser
Farmers who want to use natural products for their olive trees can use organic fertiliser, such as chicken manure. Use kitchen compost as an alternatuve organic fertiliser. Do not use fertilisers designed for grass and lawns, or any other fertiliser with much more nitrogen in it than phosphorus. Evenly balanced commercial fertilisers are best for use with olive trees if organic fertiliser isn't available.
How to fertilise
Wait to fertilise olive trees until mid-March, and do not apply fertiliser at all after mid-August to avoid encouraging new growth, which the cold may damage. Do not apply fertiliser directly against the base of the tree; begin laying fertiliser 10 to 13 cm away from the trunk. Apply a circle of fertiliser around the tree, spreading it out approximately as wide as the leaf canopy.