Though I am enthusiastic about my collection of new Japanese maples (we just bought a house last summer), I am still fairly new at this. So, forgive me if these are basic questions that I should know already. I know there is no "right" answer when it comes to providing some sort of shade to various cultivars, is there a general guideline I can follow? I live in the bay area of northern CA, so we have relatively cool winters, followed by very nice springs. Usually though, our summers can get quite hot, with probably 10 days or so of 100 degree weather. Of course, it's also a dry heat, which can produce bad winds for maples... So, my general plan was to leave ALL of my maples in the sun while it's still in the 60s-70s and still cool at night, and then eventually move them into a more morning sun/afternoon shade condition once the temps reach regularly into the 80s. (Right now, they get sun from about 9AM to 2PM.) I figure that's a good starting point, and if I see any distress on any plant, try further protecting it from the heat. Then I'd leave the plants in this location all the way through the end of the season, moving them back to the "starting" position in late fall. The shade I'd move my plants into would basically be by putting them all near the north side of my house. Not exactly DEEP shade, but not "dappled" either. That side of my house is generally cooler and does not bake like the rest of my yard in the heat. So, my questions are...does this sound like a reasonable approach? Is there any benefit of leaving them in relatively full sun now, with the temperatures reasonably mild? Obviously, I have some which are more delicate than others, but I figured it's better to let the plant have as much mild sun as possible now, then protect it later when it's hotter...kind of "toughen them up" so to speak. And, Red Dragon...can I leave that guy in full sun all summer? That's the "toughest" one I have. Thanks! Edit: I moved my Hana Matoi to a dappled shade spot under a larger tree already.
Living in England I obviously don't have to deal with such intense sun as there, but it sounds as if you are thinking along the right lines. Good idea to move any potentially delicate ones, like you already said re 'Hana matoi', it is generally the variegated cultivars that need the most protection from afternoon sun. One thing I would suggest, as your plants sound as if they are in containers, is to use some method to protect the side of the container that faces the sun, otherwise you might cook the roots. A pot within a pot would be a good idea, or the fabric root control type things, or I have seen one suggestion to make a cage smaller than the pot out of chicken wire or similar lined with newspaper and plant the maple in that, see here. They will do a lot better in hot sun if the roots are shaded and cool, even if the top is in sun.
maf, I have all of the standard black nursery pots in secondary pots (well, I'm working on it, I've got about 3 left to double pot). Others are in thick terra cotta pots or wood boxes, so I figure those are ok as-is. I'll try out my plan this season, and adjust accordingly. If I lose color or variegation, maybe I'll adjust next year what I do. The one thing I know is bad to do is once I move to shade, I don't want to put them back out in full sun.
Hi cthenn, I always chuckle a little to hear the Bay Area described as a climate. (Since you live there I'm not accusing you of doing it!) As if Pacifica, Piedmont and Walnut Creek were even remotely similar. :) Of course even within San Francisco or Oakland there is a pretty big variation. If you live in the hot east bay, I guess I'd go with partial shade from the beginning. My fear otherwise would be that you're just stressing the plants unnecessarily. In the south bay, or Marin even more, the sun is much less strong. I know some folks in Mill Valley who have a few Japanese maples in morning sun. Some friends in Redwood City have a Bloodgood in full sun that does fine, but it's in the ground and so more able to resist. The black pots can really heat up in the sun, and fry the roots, so be careful. HTH -E
You could also "bury" your containers in wood chip piles. The wood chips will insulate the plants and reduce solar exposure. Large chunky wood chips (typically available free from city tree crews or private tree companies) or large bark nuggets are cheap and work well.
emery, unfortunately I'm in the hotter east bay. Again, right now it's only as warm as the low 70's, and it's still quite cool at night. I want to give them some sun now while I can...don't they need some to grow healthy, and for the leaves to reflect their "true self" (especially red dissectums)? As far as the black pots go, I have them all double potted, so hopefully the sun will not beat directly on the "inner" pot.
cthenn, "unfortunately" is a relative word. It may not be as good for maples, but it's much more agreeable most of the summer! :) (I lived in the fog of the Sunset for 5 years. Winters were nice.) It's true that most maples don't do well in heavy shade, and that in particular red palmatums need some sun to keep from fading. But the sun in the east bay gets really strong, even when it's not that hot yet. I think experimentation will give you the right answer for your particular situation, personally I'd err on the side of caution: start with only morning sun, then if you find the reds aren't performing satisfactorily you can add back some sun. As for the pots, if they seem hot to the touch you can bang a thermometer down the side easily to see just how hot the roots are getting. -E
Emery is right. What people forget to look at when it comes to sun exposure is LATITUDE. The closer to the equator you are, the more direct the angle of sun will be, and the more intense the light will be. So all day sun in Nashville is MUCH different than all day sun in Seattle. I have to adjust the sun exposure in my area accordingly. Plants need fewer hours of sun to get "full sun" exposure.
"The coldest winter I ever spent was a summer in San Francisco- attributed to Mark Twain (incorrectly) I lived in Oakland and San Leandro for 6 years. The weather there is almost perfect. Summer temps never got too hot thanks to the bay breeze, and the fog burns off by noon most days. I didn't collect maples then, but Lake Merritt in Oakland had a great Bonsai garden with some incredible maples.
So if it wasn't Clemens who said it, who was it? I knew a couple of people who live around Lake Merritt. I think it really has the ideal climate on the planet, just lovely. -E
Apparently, no one knows who actually said it. It is wrongly accredited to Twain, Jack London, and Oscar Wilde in different places. I agree with your view of Lake Merritt. Unfortunately, land is too expensive, and I could barely afford an apartment near there, certainly not a yard for maples.
In the Sound Shore area of NY I have all my maples in part sun, mostly morning sun, a few in afternoon sun, but those are all in the ground. We can get very hot in the summer, but very humid. I may miss a little intensity in early spring or fall color on a few trees, but they all do very well. I still can get leaf burn on the more sensitive maples even with morning sun. I think you have to experiment, but I do not think you need to worry about giving them full sun in the seasons that might allow it. Japanese maples do very well in part sun all the time, and when it is too intense you might go down from there. Now all my shading is deciduous, so they have no shade this time of year, just lower sun, and are leafing out before the cover oaks.
