Planting Japanese Maples is really pretty basic and following general good planting practices will provide a nice home for your new tree. Here are a few important planting rules to follow;
Selecting a good location based on sun exposure, drainage, soil conditions and space available as well as soil condition are the keys to providing an environment that will keep your tree healthy and happy.
Lets first talk about sun exposure:
The standard rule of thumb is Japanese Maples prefer a mostly shady location. This is true for most varieties. Something to consider is where you live. I have seen some red laceleaf varieties do very well planted in full sun in northern states. The same varieties suffer and eventually die when planted in full sun in Oklahoma, Texas and even Kansas. Here is a link to my Where to plant page for additional information on choosing the proper location based on which type of Japanese maple you are planting.
Next is soil drainage.
Japanese maples prefer moist but well draining soil. I recommend first digging the hole and filling it with water. A good location will drain within a couple hours. An ok location will drain in 6 hours. If your location takes longer than six hours to drain I would recommend choosing a different location, possibly a higher location or one with different soil conditions. If you do not have a well draining location, you can always create one by hilling up an area or creating a raised bed or planting area.
Important: Adding gravel or loose media to the bottom of a poor draining hole does not help drainage, it just means you have gravel in the bottom of a poor draining hole.
Proper soil makeup or condition:
Japanese maples do well in most types of soil. I recommend a loose media; consisting 40% fine silt or sand (usually your native soil), 20% peat moss and 40% organic compost. This mix will provide good drainage combined with good water and nutrient holding capacity.
Japanese Maples prefer a slightly acidic soil PH, incorporating 20% peatmoss will lower the PH and add some moisture retention to the soil.
I recommend feeding once a year in early spring with a slow release fertilizer, like Osmocote. I use 19-5-9, or 18-6-12. Anything close to this ratio will work just fine. Avoid liquid fertilizer once Japanese maples are established and any time after mid-summer. You want the trees to properly harden off before winter.
Allow enough space for your Japanese maple tree:
Be sure to consider the space available, both height and width of the planting location when choosing a tree. Most standard palmatum type varieties grow 15-20 feet tall and 6-8 feet wide. There are some smaller growing varieties that only reach 6-8 feet and work well next to buildings and under overhangs.
Laceleaf or dissectum type varieties generally grow to about 6-8 feet tall and wide. These are easier to keep smaller and pruning twice a year will help maintain their size. I recommend a light pruning once in late spring and hard pruning in mid to late winter.