If you are growing your Japanese Maple in Southern California, Arizona, Nevada, New Mexico or other desert biomes that are hot and dry you'll need to give extra care to your maples. First and foremost is the importance of overcoming the hard water that is typically produced in these areas. Hard water produces leaf margin burn that needs to be neutralized prior to damaging your tree. Tree placement and soil type are also crucial ingredients in growing healthy Japanese Maples in hot, dry, climates. The water in areas where annual rainfall is less than 18 inches is alkaline, hard, and is high in mineral salts. To neutralize the hard water you must first amend your soil with gypsum. After amending in small quantities (approximately 2%) it is recommended to add a 1/4" inch layer of gypsum around your tree before covering with 1-2" inches if soil and mulch. The mulch insulates your trees from extreme temperatures.
Pacific Coast Maples also recommends a product we sell called ProteKt to assist with the hard water in these dry areas. ProteKt is easy to use in that you mix 1/2 teaspoon of ProteKt per gallon of water. Watering with ProteKt every week to every other week is sufficient. Japanese maples in these areas need a heavy watering every month to assist in washing away the salt buildup. If is also recommended that you water your maple every few weeks with a homemade solution of 1 tablespoon of distilled white vinegar mixed with 5 gallons of water. The solution should sit over night prior to watering your maple.
Japanese maples should always receive afternoon shade. These beautiful trees due well in high heat conditions but do not do well in high heat conditions if they are exposed to the Sun's direct rays after noon to 1 p.m. Tree placement underneath a larger tree's canopy or on the North or East side of your house is strongly recommended. Planting your maples in an area that is somewhat protected from wind gusts is also important. If your maple is grown in containers (see Pacific Coast Maples-Growing Maples in Containers article) they should be planted in an Azalea Mix or another type of potting mix that has a slightly higher acid content. Before replanting your little tree it is important to select a container that has several holes in the bottom for drainage. If your tree is being planted indoors and your container does not have drain holes you'll need to watch the amount of water you use so that your tree does not drown.
Container maples need to be given a light nutritional supplement such as the one we use in our nursery Grow 7-9-5 by Dyna-Gro. Grow 7-9-5 is preferred but Rose Food is more than adequate. If you do purchase Grow 7-9-5 from our nursery you'll need mix it at a ratio of 1/2 teaspoon per gallon of water (same as the ProteKt). Grow 7-9-5, ProteKt, and Rose Food are inexpensive ways to help insure your plant is healthy and thriving.
We wish you the best in growing your maple in the hot, desert, climates. Please give us a call if you have any further questions.