In your garden, Japanese maples will want a spot that gets about three hours of morning sun, then filtered shade during the warmest hours of the day. The hotter your summers are, the more crucial this balance of sun and shade becomes. When maples get too much sun and heat, laceleaf and variegated types scorch, while red-leafed varieties take on a burned bronzy sheen. At the other extreme, dense shade causes variegated, red- and golden-leafed varieties to turn green, and it mutes the color of winter bark.
Plant Japanese maples in the ground in loose, porous soil that affords good air and water penetration. To improve native soil, amend the backfill from the planting hole with an equal amount of organic matter (use peat moss if your soil is alkaline) and cover the root zone with an organic mulch to keep the soil cool and moist.
Since maples have abundant surface roots, they do well in relatively shallow and broad containers. Plant them in a high-quality potting mix.
You can spur growth of all kinds of maples with an application of 5-10-10 fertilizer as leaves emerge in spring and in early summer. Potted plants need only one dose of controlled-release fertilizer in spring.
Water when the soil beneath the mulch dries out. Hard water is trouble, since it is usually accompanied by high pH and salts: Some gardeners use rainwater.