I am hoping those with more experience can shed some light on my situation. I will try to be as brief as possible, yet still give detailed info... (For reference, I live in Kansas, zone 6b) Early last spring (2010), I purchased a small 4" potted Kojo-no-mai from a nursery out of Louisiana; it was shipped to me in beautiful condition. I repotted it upon receiving it into what I thought was a well-draining mix (I have read these plants don't like to be water-logged). Everything seemed to be fine, and the Kojo thriving, up until about late June, when all the leaves started to get a little brown on the tips and edges; this gradually covered the whole leaf, with the leaves getting 'wilty', and then ultimately falling off, leaving it bare. This took place over about 4-6 weeks. As I was worried the soil mix I had chosen was too water-retentive, I took the risk of transplanting it into a much grittier mix (mostly an akadama-type bonsai soil mix with some tree & shrub soil added for the organic component). This seemed to help, as by August, I was seeing new growth again on the plant, and it seemed to do well the rest of the growing season. As I was so enamoured of the little guy, I purchased another 4" Kojo from the same nursery Sept 2010, and potted it in the same mix as the first one. Both did well over our exceptionally cold winter (protected in a cold frame), and while there were few flowers come spring - I didn't expect much as they were small plants - they started leafing out very nicely. I started to hope that things were good to go, when both plants started going down the same road as last year - leaf tips and edges browning, then spreading to the whole leaf with it going wilty and ultimately falling off. Again, this started around June, with the whole process taking about 4-6 weeks, so by mid July, I had bare plants again. They did start to leaf out again slightly in early August, but by early September, both plants were dead despite my efforts. This summer was particularly unkind to plants here in Kansas, with over 50 days of 100F or more for daytime highs, with overnight lows barely hitting the low to mid-80s, so all my plants suffered, with me losing several maples, dwarf conifers, etc. However, I found it unusual that exactly the same thing happened to the cherries as last year, around the same time. For general care, in the spring they were fertilized every two weeks with a mild bonsai fertilizer (my goal with these plants), along with some Superthrive every now and then. They were watered when the soil felt dry about an inch down. I stopped fertilizing once the temperatures started to consistently stay in the upper 80's or low 90's as I didn't want to burn the roots, and didn't/don't start up again until later in summer/early fall. As the leaves of the Kojo, at least the young plants I had, seemed to be quite thin and sensitive like those of my maples, I made sure to keep them protected from the worst of the wind. As for sun exposure, initially they were on my front porch (ESE), receiving sun until early afternoon, then bright shade the rest of the day. Once the temperatures became too hot, I moved them (along with all my other plants on the porch, which were suffering heat-stress as well) to a sheltered corner of the backyard under some large trees; there, they received sun until about 10-11, with bright dappled shad the rest of the day. All the plants moved to the corner did much better after that, though I still lost several. I have been told by the nursery where I purchased the Kojo's that cherries can be more sensitive to stresses - heat, build-up of salts in the soil/container, chlorine in the water, etc - than other plants. The nursery, too, was at a loss to explain why things were happening as they were with my plants. I feel that I was looking after them properly, but if I was doing something wrong - or neglecting to do something - I would love to know what it is so that I can correct it. I have just purchased a 3 gallon Kojo - should be delivered tomorrow - that I am hoping to have better luck with. If cherries are, in fact, more sensitive, I am hoping that a larger plant with be better able to handle these stresses. Any advice, suggestions, recommendations, etc, would be greatly appreciated. I love the flowering cherries, but am starting to think I have a black thumb when it comes to keeping one alive... Andrea
It sounds very much like an excess of salts in the soil mix. Salts can come from a variety of sources, including your water. Some water is naturally mineral rich ("hard") and the minerals (calcium, magnesium, potassium) can form salts. Water softeners use sodium, which can also be a problem. Another potential source is the fertilizer charge that comes with proprietary soil mixes, and, of course, the fertilizers you're adding later in the season. In some cases, an excess or absence of a particular micronutrient (such as boron or manganese) may cause marginal necrosis and/or premature leaf drop. Sometimes an excess or imbalance of nutrients can cause a deficiency in others. For example, high available calcium (common in high pH soils) can cause manganese deficiency, to which cherries are particularly sensitive. Another complication is the "well-drained" soil mix, which, although effectively preventing water-logging, may be contributing to salt damage because it lacks the ability to buffer changes in soil chemistry. On the other hand, most loamy soil has good buffering capacity. Without a specific soil test, it may be impossible to determine what is causing the problems. Nevertheless, the problem may be easily overcome by reducing fertilizer applications and increasing the buffering capacity of the soil (by adding more loam and/or well-composted organic matter). Cherries are basically sensitive to salts.
I know we have hard water, but we don't have a water softener, so would you recommend leaving the water out for a few days prior to using it? Is there anything else I can do with regards to the water? I am hoping to pick up a filter for the outside tap to help remove the chlorine, etc; what should I look for in a filter, or is there one you'd recommend? With regards to fertilizer, I have changed to an organic fertilizer (Fox Farm's Japanese Maple fertilizer, 4-8-5) and have also started adding some bone meal to my soil mix when potting new plants. I still use the Superthrive 1-2 times per month when watering. Would these both be suitable to the cherry, or is there a particular fertilizer you would suggest? I plan on using the JM fertilizer 2-3 times in spring, and again in fall, along with an application of the bone meal once in spring and again in fall; is this sufficient/too much? Since the cherries seem to be so sensitive to deficiencies of certain nutrients from what you're saying, is there a particular supplement they would benefit from either on a regular basis or 1-2 times per year? I have also slightly changed up the soil mix I use for my potted trees/shrubs. I was using Miracle-Gro Tree and Shrub soil, along with some haydite (calcined clay) and chicken grit, but have switched over to Fox Farm's Ocean Forest soil mix (http://foxfarmfertilizer.com/products_soils1.html), a little Fox Farm Soil Conditioner (http://foxfarmfertilizer.com/products_soils2.html) which provides the beneficial microbes, and pine bark mulch with the large chunks removed for my organic components. For my inorganic portion, it's a combination of the haydite, kanuma (an acidic form of haydite), and the chicken grit; the amount of each and the total ratio compared to organic varies depending on the plant it's being used for. (Other soil amendments I have on hand include lava sand, pumice, peat moss and cotton boll compost.) Do these sound like appropriate soil components for the cherry? What kind of ratio would you use, or would you use something different? I apologize for all the questions, but I just received my new cherry today and want to make sure that when I repot it (I'm thinking February time-frame would be appropriate?) I can start things off on the right foot and *hopefully* avoid what happened with my previous two. Thanks!! Andrea PS - Can I prune the roots, if necessary, when repotting it? How well does it take to root pruning?
