Japanese maples have been cultivated for centuries and can be a lovely addition to your landscape. They are native to Korea as well as Japan, and offer a number of different leaf shapes and colors ranging from bright green in the spring to bright red in the autumn. Japanese maples can thrive in either the ground or containers and generally grow slowly. Well-drained and acidic soil is very important, along with healthy and fertilized soil. If you are not lucky enough to live in an area with rich soil, you will need to fertilize.
Feed a young Japanese maple in the spring or summer beginning with its second year. If it's in the ground, fertilize the young maple once a year. If you have very rich soil, you may not need to fertilize at all. On the other hand, if you have very poor soil, you may need to fertilize twice a year. If the maple is in a container, you may want to fertilize more frequently because nutrients tend to wash out of containers.
Sprinkle an all-purpose slow-acting granular fertilizer, such as Osmocote, onto the soil 1 to 2 feet beyond the tips of the branches. These outer leaves are called a tree's "drip line." Some gardeners find rose food or fish emulsion are also effective fertilizers. You can find these fertilizers in almost any home and garden store.
Fertilize older Japanese maples from their drip line out 5 to 10 feet. Use about 1 cup of fertilizer for each inch of trunk diameter, measured at its base.
Stop fertilizing in mid-August so the trees will stop growing new shoots. Any new shoots that emerge this late in the season can be damaged by the first frost. This will also let the new season's wood "harden off" for winter and will help the beautiful fall leaf colors develop.
Examine your Japanese maple each year. After several years you may notice a healthy Japanese maple that is planted in good soil will not need regular fertilizing. If your tree seems to stop growing or the leaf color appears to be off, resume fertilizing and see if the condition improves.