Spring
To help retain soil moisture and to discourage weeds, spread a 2 to 4 inch layer of some organic material on the soil around the base of the tree. Chopped leaves, pine needles, wood chips or a similar mulch, will protect the trunk from injury by mechanical yard care equipment. Spread the mulch out in a circle out at least 2 feet from the trunk. Do not pile it up against the tree trunk.
Fertilizing Japanese Maples - Notice on the right there is now an organic fertilizer designed specifically for Japanese Maples. You might want to try it.
However, do not add fertilizer when planting a tree or during its first season. Feed young maples only once a year. In spring or summer sprinkle an all-purpose slow-acting granular fertilizer, on the soil under the tree out to 1 or 1 1/2 feet beyond the tips of the branches (the dripline). Fertilize older trees from the dripline out 5 to 10 feet. Use about a cup of fertilizer for each inch of trunk diameter, measured at the base. After several years healthy Japanese maples that are planted in good soil and are well mulched do not need regular annual fertilizing. Do not fertilize after mid-August because the nutrients encourage tender new growth which is vulnerable to damage by the first fall frost.
New Organic Fertilizer Just For Japanese Maples
Summer
The shallow, fibrous roots of maples like moist soil. If they are in soil rich in organic material which holds water well, Japanese maples need special watering only for a period of several weeks when they're first planted, and in late fall before the ground freezes for the winter. If rainfall is normal established trees should do fine. If they are in thin soil or there are periods of severe drought, however, it is important to soak the soil deeply once every week or so with a drip system or sprinkler. Mulch maple trees well to help retard evaporation of moisture from the soil.
Fall
Do not add fertilizer when planting a tree or during its first season. Feed young maples only once a year. In spring or summer sprinkle an all-purpose slow-acting granular fertilizer, on the soil under the tree out to 1 or 1 1/2 feet beyond the tips of the branches (the dripline). Fertilize older trees from the dripline out 5 to 10 feet. Use about a cup of fertilizer for each inch of trunk diameter, measured at the base. After several years healthy Japanese maples that are planted in good soil and are well mulched do not need regular annual fertilizing. Do not fertilize after mid-August because the nutrients encourage tender new growth which is vulnerable to damage by the first fall frost.
Winter
Japanese Maples generally need little pruning, other than to remove dead wood or branches that cross each other or grow too low. Occasionally a young tree will develop 2 main stems, or trunks. Cut one of these out to establish a single strong trunk. This is best done in the winter or early spring when the tree is dormant, using sharp, clean pruning saw or loppers. You may also cut out the dense inside branches of upright trees to open up the foliage canopy to air and light so the other branches can develop fully. Japanese maples will eventually shed those branches that do not get enough light anyway.
Weeping forms rarely need pruning except to avoid awkward asymmetrical growth. Snip off the young suckers that sprout along the main stems inside the tree for neatness. Prune other suckers that may appear low on the trunk, beneath the swollen graft union or from the roots. Also cut out any branches that have atypical leaves, that are reversions in size or color to the leaf type of one of the tree’s parents and do not match the rest of the leaves on the tree.