In addition to my original post my current potting mix is 2 parts fir bark, 1 part sand, 1 part perilite and a small amount of peat moss for water retention. I potted it this morning and watered it well. Drainage is very good, however, I arrived home and tested the soil-less mix and found it almost dry, but air is reaching the roots better than before. Is there some kind of compromise I can make or is the soil content adequate for preventing the leaf problems I'm facing?

At first I thought it is the hot weather as I have leave burns on my JMs here, the red leafed ones in alot of sun do get scrotched enough I found the leaves on the ground.

But then I see you are growing these trees indoors? I was told many times you can't grow them indoors as it is probably too dry. Actually it does not seem like the plants are able to get enough sun from where you put them.

Your potting mix have very little water holding capacity. I tried something very similar to your mix, I find that the roots actually grow very well in it.. frequent drying out and watering is good for the plant. but it dries out too fast and it requires watering at least once a day. I switched to a heavier soil that only requires watering every few days and it is also a closer match to my yard (clay soil) than sand based or peat based mix.

I don't know exactly what is causing your problem but from my limited experience:
I am not sure if superthrive every week is needed or even excessive? The roots do need to take time before they get comfortable. So you should stop repotting it especially when it is kind of hot now. I do have few JMs planted in all different soil from sandy to clay, JMs seem to thrive in a variety of soil as long as it is not lodged with water, with careful watering you can pick your own mix.
I also think maybe you should consider moving the plants outside but with some kind of sun protection.

Hi NoBreyner,

One thing you have to understand is the different climate conditions your maples were growing in before you got them. Having to make the trip to your place and adjust to the new environment stresses the plant a little or a lot. That, with the addition of being repotted several times in different potting mixes can take its toll.

You are not allowing the trees to acclimate to their new environment. Japanese maples can take up to a year or two to adjust properly. Some adjust quite well and others take a beating, but the thing to realize it that Japanese maples, as delicate as they are, are also quite resilient plants.

Your mixture of 2 parts fir bark, 1 part sand, 1 part perlite, and some peat is good. I use a similar mix. I've mixed my own with similar ingredients, but decided to try using Whitney Farms' cactus mix with good results. I suppose their bonsai mix might be good too, but it is more expensive. The cactus mix is made up of fir bark, sand, pumice, composted animal manure, and peat. To this I add a bit more pumice, but not too much. It has good drainage and moisture retention...much better retention than the all fir bark that my Bloodgood is sitting in right now as it came from the grower.

If it is so hot that you need to water once daily or even twice daily then that's what you have to do to care for your maples. My father who raises bonsai in shallow unglazed ceramic pots HAS to water his plants twice a day or they dry out too much. Some of my maples need to be watered once a day when it gets in the mid 80s here in Los Angeles. My maples get morning shade and afternoon sun from 12:30p on. All of my maples are in plastic pots (save for one in terra cotta) which helps with water retention.

Regarding keeping the trees inside because it's hot. Don't. Maples are outdoor plants and that maybe why they're not doing so well. Find a shady place with maybe a couple hours of direct early morning sun and then *gradually* introduce your trees to more direct sunlight. Morning sun afternoon shade is ideal, but not written in stone. Like I said I have morning shade afternoon sun as I live in a west-facing apartment. Here in Los Angeles it gets up to 100 degrees too. Some maples are more sun and heat tolerant and can take it while others can't and the leaves dry up. There is one red culitvar in the ground at a Buddhist temple in Little Tokyo that gets full sun. Last year I witnessed this beautiful tree's leaves fry up in the hottest part of summer and stay that way the rest of the year only to come back this spring. This goes to show you how amazing these trees are if given proper care.

Regarding fertilizers and such. Dyna-Gro is a good product to use. Don't overdo the Superthrive as it could lead to abnormal growth down the line. Nothing adverse...just bigger leaves and such. Instead of Superthrive (because it's expensive) try using liquid kelp extract at the same strength you use Dyna-Gro. Mix it in with the Dyna and water. Again, don't overdo the kelp.

If you sprayed oil based fungicide or insectcide keep your maples out of the sun as the oil seems to "cook" the delicate leaves. That is what happened to my Bloodgood. In fact, I would advise not using these on Japanese maples all together. You might try this: mix a weak solution of Simple Green and spray the leaves with this. I've used it on my various plants to knock down insects and so far it has had no ill effects on any of them. This includes succulents, azaleas, and a couple maples. Honestly though, given what you said I doubt that your problem is disease. It's most probably a watering issue.

There's usually two main issues with plants not doing well. One is watering...either not enough or too much. Two is light...again either too little or too much.

Hope this helps and let us know how it goes.

Layne

Thanks for the quick responses PoorOwner and Layne. Actually Layne I went with your reccommenation from another post for the potting mix. I will keep the trees outside and keep an eye on the water needs for a few weeks, and I agree that it will need watering at least once per day. It gives me an excuse to give them more attention. I will also lay off of the Super Thrive. I will keep all my maples outside from here on out. And who knows the green leaves may turn red again!

Hi NoBreyner,

You might want to get a simple moisture meter that you stick in the pot and give you a reading on a dry/moist/wet scale. I admit to using this. I've been using it at my old place and then stopped using it once I got down how my maples use up water. I'm using it again at my new place since the conditions are so different. Use it for a while till you get the hang of how much water your trees need. Remember, their water needs change during the year.

Layne

It has been one day since leaving my trees outside and one of the immature leaves seems noticably larger. The leaves on the tree turned solid green two months ago. Todays experiment is showing two of the leaves have some red in them again. When I left it out before I thought that was the bronzing of the leaf that I read about with Oshio Beni's. I will buy the moisture meter first thing in the morning. Thanks for all the help!