Fertilize your plants in late fall/early spring to ensure maximum growth during the growing season.
Tree roots usually grow within the upper 6 – 24 inches of the soil. Generally, they occupy an area of around 2 – 4 times the diameter of the crown of the tree. The tree's root system performs essential functions including obtaining oxygen, water and minerals from the soil and storing nutrient reserves during the winter months. Roots also anchor the tree in the ground. When a root system becomes severely damaged, the whole tree must be removed. It's vital to maintain a healthy root system to prolong the life of you tree. Fertilizing during the winter can help to encourage deep root growth.
If you choose to fertilize your trees in the winter make sure you do so after the first hard frost to ensure that the tree is dormant. This will prevent the growth of tender shoots that will not have time to harden off before the freezing temperatures arrive. A well-timed shot of winter fertilizer will give your trees a jump-start on spring growth by ensuring the soil is rich with nutrients once the temperatures become warm again.
Choose the correct fertilizer for your tree. Deciduous and evergreen trees prefer a complete fertilizer with an analysis of 12-4-8. Citrus and other fruit trees will prefer a specialized fertilizer depending on their type. Follow the instructions carefully, making sure that you do not over-fertilize. The best type of fertilizer for trees in winter is a liquid nutrient that can be injected into the ground at the level of your tree's roots. The feeder roots are located just inside and just outside of the tree's canopy drip line. Injecting at these locations will ensure that the nutrients are readily available to the tree once the growing season resumes.