I dug a 10-12 year old Japanese Maple tree from the Washougal, Washington area in the snow and took it to Sherwood Oregon. I transplanted it in a mostly brown and grey clay soil mixed with a 3-way soil mix (topsoil, sand and compost) I kept some of the soil the tree came from of course and used it as well. I also used a 2-2-2 granulated lime/fertilizer blend. I first dug the hole, sprinkled about 4 cups of the 2-2-2 fertilizer in the bottom of the hole. I covered it with some 3-way soil. I placed the tree into the hole. I covered the roots with existing clay and 3-way soil and used about 3 to 6 cups of fertilizer in and around the roots and then repeated the process with soil then fertilizer again and topped everything off with the 3-way soil and another 3 or 4 cups of 21-4-21 fertilizer.
My main questions are: do you think I did ok with the amount of fertilizer; could/should I have done something else, and can I go back and do anything else? The surrounding ground outside the rootball is very dense clay. Should I go back with a large tiller and chew the surrounding 3 feet outside the root zone up real good and blend 3-way soil and add more fertilizer? What's your feedback? Thank you for any help you can be.
Keep weeds from competing with your maple. Remove all grass and weeds under the tree canopy. Mulch can help. A 3- to 4-inch layer of organic mulch spread over the tree's root system helps conserve moisture, moderate soil temperature and prevent weeds. Keep mulch about 6 inches away from the tree trunk.
Most publications will recommend not to fertilize the new transplant for several years and to not mix fertilizer with the soil used because this practice can lead to root damage. However, adding a low amount of a low nitrogen fertilizer and root stimulator during planting will help nourish the tree and aid in survival.
Other recommendations include watering the tree thoroughly after planting. Drip water slowly into the basin, refilling as it seeps through until water is left standing on the surface. Repeat twice in the first week. From that time on, water when the soil is dry 3 to 4 inches below the surface. Absent significant rainfall, deep-water the soil around the maple's roots around twice a month.
Also, for a tree as old as the one you transplanted, it is often a good practice to orient the tree as it was growing in the previous location. Fill the hole with the extracted soil to the same level on the trunk of the maple as in its prior location.