Fig Nutrient Needs
Figs thrive in soil with average fertility and in areas of the garden where there is little competition for nutrients from other trees. If kept in poor soil or if the tree is crowded among other trees, especially fruit trees, your fig tree may not get enough nutrients to grow lush leaves and bear fruit. With their high-nitrogen demands, nitrogen may be all that's needed to give fig trees a boost, but in poor soils where a variety of nutrients are missing, a balanced fertilizer is best for your fig tree.
Signs of Deficiency
A soil test kit will accurately tell you which nutrients your soil is lacking, but you can also watch your figs for signs of deficiency. If the tree's leaves turn yellow or if the tree is showing slow, stunted growth, your tree needs extra nitrogen. If the edges or tips of the leaves appear brown, the leaves have a red or blue cast to them or if the tree fails to fruit, your soil lacks several nutrients.
Feeding Your Figs
If your fig tree has a nitrogen deficiency, blood meal will give the plant a boost. Blood meal has an N-P-K ratio of 12-0-0, giving it the one of highest nitrogen percentages of natural fertilizers. For fig trees lacking a variety of nutrients, opt for a balanced fertilizer with an N-P-K analysis of 8-8-8 or 10-10-10. The best plant food will be one that is specifically formulated for fruit trees, because it will also contain the many micronutrients fruit trees require.
Applying the Fertilizer
Because blood meal can scorch your trees if you use too much, do not over apply it in the hope it will jump-start your fig tree's poor growth. Blood meal should be applied at a rate of 1 to 5 pounds per 20 square feet every four months. If you're using a balanced plant food, apply one-third of a pound for every foot of tree height. For example, if your fig tree is 9 feet tall, apply 3 pounds of fertilizer per application. Balanced plant fertilizer should be given in late winter, early June and again in the middle of July.