In regard to fertilizer application, after you have pulled the mulch away from the drip line do you break up the ground and apply the fertilizer or do you just apply the fertilizer to the top of the ground and then replace the mulch. I am aware of the tiny fiberous roots on the top of the ground of most of the Japanese Maple cultivors and was not sure if breaking the ground up applying the fertilizer and then replacing the soil was the way to go or just applying the fertilizer on top of the ground and then replacing the mulch was the way to go. I appreciate your time. Thank you, Lynn Wilson
Japanese maple cultivars, as well as other Acer species don't usually need supplemental feeding when grown in the garden (i.e., in soil), unless the fertility is inherently low, such as would be found in a gravelly soil. Plants do require some feeding in containers, but even here, many people apply excessive amounts. Most plants are perfectly adapted to finding moisture and nutrients in the soil on their own. Annual applications of leaf mulch are usually sufficient to grow great trees. (Picture a forest, where leaves fall to the ground every autumn and are incorporated into the soil and transformed by the organisms there--these trees don't need extra fertilizer.) Slower growing, unfertilized Japanese maples usually look more "natural" and suffer less from drought-stress, pests and disease. Granular fertilizers (such as the commonly available 6-8-6) generally require incorporation to be effective, and are practically useless in coarse textured soils when applied at the surface. Soluble fertilizers are applied in solution and poured over the soil (or through a mulch). However, this is an expensive and mostly wasteful method for trees, because soluble nutrients are usually quickly leached away. Controlled release fertilizers are also expensive, but more cost-effective, as they can be applied to the soil surface and they meter out their nutrients slowly, usually depending on the thickness of the fertilizer coating and the temperature. If they cannot be incorporated, they are best applied at the soil surface, below the mulch layer.
Lynn - Whether to fertilize Japanese Maples or not and when to fertilize has been one of my most frequently asked questions in my travels to visit Southern and Central Oregon nurseries in the past. A lot depends on what type of watering system you are using and what kind of soil do you have. There are no easy answers and a lot depends on whether you feel a need to fertilize or not, how much rainfall do you get, how cold or warm are your temps, are the Maples grown in containers or grown in the ground and in quite a few cases which varieties and perhaps species of Maples are you considering to fertilize. One thing we have found is that some varieties of Japanese Maples do respond well to fertilization, some do not and with some Maples it is probably best not to include a fertilizer with any Nitrogen. A 0-10-10 may be best for many but not all variegated Maples. As far as variegates one thing we have observed in the past is that too much vigorous growth will yield a major reduction in the amount of variegated leaves that we can see. Use a 6-12-6 on a Roseo marginatum, Butterfly, Beni schischihenge, Orido nishiki, Asahi zuru and Higasayama to name a few and you can expect to see a dramatic reduction in the amount of pink and white and in one particular case orange in the leaves as soon as the form of Nitrogen that can be readily utilized by the plants has been made available to the roots. Some varieties of Maples are not strong growers as opposed to other forms that can "grow like weeds" for us. A lot depends on your climate as we get around 4-5 growth cycles or growth spurts in a year where we are. Whereas in areas of the Pacific Northwest a grower may only get 2 growth cycles a year. What is important is to know your Maple and have an idea as to how it is supposed to look like once mature. As for your situation I would need to know what kind of drip system are you using and how long have you used that drip system on that Maple. Are their more than one drippers used for the Maple in question and what volume of spray is being emitted. With you using a drip system I would not advice you to use a commercial grade fertilizer that is pelleted containing Nitrogen as your watering set up will not incorporate the nutrients down into the soil soon enough. A liquid emulsion with a drip system can burn the roots of the plant as you cannot nutrilize the fertilizer fast enough, unless of course you use a half strength or less solution of a liquid fertilizer versus water. If you want to use a liquid form of a fertilizer with Nitrogen I would suggest a quarter strength solution with a conventional drip system (yes, that is a definite generalization as a lot depends on your system itself and how much water is being applied to the plant). People can come back at me in regards to drip systems but I am "old school" as I prefer bubbler heads running off a drip line or at least a dripper with a three-prong spray head and more than one head to better apply the water evenly over the better part of where the root system should be. Some people are dead set against fertilizing with a granular or liquid fertilizer but instead prefer to use a mulch of predominately pine or fir ground bark which will help aeration of the soil and will still provide some nutrients to your plant. Certainly not all of our quest to fertilize our plants involves the incorporation of Nitrogen. In a lot of cases it is the micro-nutrients that our plants may need and symptoms of nutrient deficiencies are not always visible to us. Should your plant become chlorotic then you have a problem as Nitrogen will mask the chlorosis by a possible quick-fix greening up of the leaves but when the plant becomes stressed the yellowing will show up all over again and can be quite difficult to correct the next time. In my mind too much emphasis has been placed on Nitrogen as a panacea for fertilizer problems as our culprit may indeed be a Calcium, Iron or a perhaps a Manganese deficiency instead should we have a deficiency at all and to be honest, in Maples deficiencies are not all that common but in the San Joaquin Valley we do on occasion see some nutrient deficiencies that many other areas of the Pacific Northwest seldom ever see or ever have to endure. For you a granular 0-10-10 with some micro-nutrients lightly sprinkled on top of the soil a good distance away from the trunk of your Maple might not be a bad idea for you considering that your mulch can act a fertilizer in its own way (no, I do not plan to get overly technical here). The only form of liquid I could suggest is also a 0-10-10 with some micro-nutrients in its content also. I would not use a fertilizer with Nitrogen at all for your program. The only times of the year I can recommend to use a fertilizer is in the Early Spring either right at juvenile growth or during the first growth spurt and during the Winter using a 0-10-10, especially for container grown plants. In the ground a 0-10-10 fertilizer may not be a bad idea for you but that is your choice depending on if your Maple does not color up well in the Spring and the Fall and the factors are not solely due to climatic or environmental conditions. I do agree that in most cases a commercial fertilizer is not needed for Maples but where we are located a low or no Nitrogen fertilizer supplement can be a very handy tool for us. Jim
I've been out of the Maple game essentially for 9 years after my mentor in Horticultural plants for just over 10 years Donald Kleim of the since defunct Henderson Experimental Gardens passed away. A lot of you out there would not have several varieties of Maples today had it not been for Don Kleim, either from his original imports of plants from Japan and elsewhere, as well as the plants that he grew along and monitored of which some varieties later became nursery trade introductions. The "old guard" in Maples worldwide know exactly who Don Kleim was. The problem that I now have is after awaking from a I really do not want to have anything to do with ornamental plants stupor is that I've since learned other people whom I was fortunate to know and talk to about Maples in years past have also since passed away. It appears I am all alone now as I have no real backups in place for when I really "step in it" and could use someone to either condemn me for being foolish or be a sounding board when needed for when I write something based from first hand practical experience and no one likes my input at all. No matter what other college level degrees I may have been accorded I am an Agronomist by trade, even though my specialty areas have seemingly always been Fruit & Nut trees and Citrus. I will not go into detail in this forum as to who and what I am but I will let out a secret now in that I've had a Pest Control Advisors license in Fertilizers ever since its inception back in 1974. I realize that fertilizing Japanese Maples is not something that many of you will need to deal with any time soon, at least that is what my perception is based on what I know from years ago until my re-awaking from my being brain dead towards a group of plants I have been growing as a plant collector for over 20 years. It mattered not to me what others were doing in Maples as I had my 100+ varieties to deal with and I was happy with what I already had and felt I did not need any more for a long while. I did have 15 varieties come in to me recently to serve as a rejuvenation of sorts but I just do not feel right about writing much on plants yet in this forum or in the other forums offered by such a great host - UBC. It is going to take a while for me to get back up to "speed" with Maples again. Essentially I fell in love with Maples and then fell out of love with Maples and am now wanting to know if the marriage can still work or not. That is where I am at today. Jim
