A wise man (Mr Shep aka Jim) once told me that we tend to over fertilize our maples when they are young and then don't give them enough as they get older. This started my in-depth research into finding the best fertilizer for Japanese maples. For me, a great fertilizer must provide healthy roots and a dense healthy canopy. The growth must be true to form (proper leaf color, size, and a short length between leaf pairs). It should promote healthy growth all along the branch and not just at the tips. Promote back budding. The new growth needs to be of proper rate and length throughout the entire tree (not long and leggy randomly placed shoots). The growth needs to be dense (not long and thin) that can harden off by winter and not die back. The growth also needs to be sustainable, able to stand up to the heat of Summer. The tree must remain healthy and free of bacteria, pests, and disease. The spring and fall show needs to be long lasting with great color. Organic and slow release is important too. It must never burn or kill your tree if you make a mistake and apply too much. PHC ROOTS 7-7-7 fertilizer meets all of the above criteria. All organic, slow release with added beneficial bacteria and microbes that improves the health of your soil or pot mix and your tree. This is hands down the ONLY fertilizer that I will use on maples. I have been using for 4 years after a 10 year hands on research project on fertilizers. This fertilizer is available from AM Leonard. A.M. Leonard Tools for the Horticultural Industry since 1885. Just a quick note, they offer free shipping (a few times a year) as a promotion if you can't find it locally and are budget conscious. This is the only fertilizer that I can recommend for Japanese maples. You will get growth that is healthy and true to form. No long leggy shoots or reversion. You will have healthy sustainable growth, back budding and fullness. The tree will stand up to seasonal extremes by the third season of use limiting winter die back and sun burn during summer heat. Also by the third season you will be amazed by the health and beauty of your trees. You will have longer lasting shows of color that you only thought were possible in the pictures used in books and online to sell these varieties. Some of my oldest trees in my collection seemed to loose their spring color or it was very short lived, but now the color is back and sometimes it lasts for several days and even weeks. Many also get a great show with the second push of growth that used to be muted or non existent before using this fertilizer. The fall color lasts for weeks and the trees are not quick to loose their leaves. I use the PHC 7-7-7 for all container and landscape maples, shrubs, conifers, and perennials. I use it early spring, summer; in my area that's April 1st, end of June, and then September 1st I use: PHC® 3-4-4 Fertilizer for Acid-Loving Plants, 25 lb Bag A.M. Leonard Tools for the Horticultural Industry since 1885. As a winterizer. Its also great for evergreens and flowering shrubs. For all fertilizers I use half the recommend dose. It can be mixed in the soil for re-potting and planting. A note about bacterial infections and synthetic fertilizers. Synthetic fertilizers fuel bacterial outbreaks. Do not use them! When I get a new tree the first thing I do is rinse away the synthetic fertilizer and dispose of it. (those with lawns keep the synthetic lawn fertilizers away from the root zone of your maples. Better yet, don't use them on your lawn either.) The other problem with synthetic fertilizers is that the growth is usually not true to form and will destroy the structure and character of your tree. The growth tends to only be at the tips making the tree look more sparse over time. The long shoots of growth caused by synthetic fertilizers are very porous and less dense increasing the likely hood of winter snow damage and wind damage. The branches tend to be more likely to die back over winter and the foliage tends to burn easier in the Summer heat. I find all this to be true even with the most expensive slow release synthetic fertilizers that cost more than $90 for 25lb bags. Reversion along with loss of spring color also have been a problem with synthetic fertilizers in my experience. My advice is never use them on Japanese maples and other slow growing ornamental trees and shrubs. PHC roots are the only fertilizers that I will recommend. PHC stands for plant health care. I used to be of the option that Japanese maples don't need fertilizer. That was until a wise man (Mr Shep aka Jim) told me that we tend to over fertilize our maples when they are young and then don't give them enough as they get older. I noticed that this was the case with some of my oldest specimens, so his input really hit home with me. At the time organic fertilizers left a lot to be desired, but in the past several years they have come along way and the best, I have found is PHC roots. There was a time that I was not comfortable recommending a fertilizer, but now I can with confidence. Note that I have no relationship with phc roots or am Leonard, I do not benefit in any way by my recommendation. I recommend it from my research and great experiences. I want to see other people have great success with their maples. It makes me sad to see people lose their trees to stress and bacterial infections. I like to share my knowledge so that people can have healthy and happy maples! Japanese maples and their beauty bring me so much joy. I want others to experience that beauty, joy, and the fun that comes in growing them successfully.