When to move my maples?

[glass_shark]

Hey all, I have a bunch of maples that are getting some nice leaves on them! Very exciting! I currently have them in my greenhouse which is off to the side of my back deck, it gets some dappled sun in one corner and shade on the other sides (of the greenhouse, the deck is a similar situation though if anyone was wondering) I wasnt sure when or if I should move the maples that are starting to get leaves, should I wait until the leaves harden or should the new leaves be getting a bit of sun? They're pretty happy in the greenhouse now, but I worry about when it gets warmer, will it be too warm in the greenhouse for them? I haven't had the greenhouse in the summer months yet, so I'm still figuring out using it.

 

[HamburgerTrain]

I have a similar setup. I unzip the greenhouse during the day to vent then close it in the evening. Id wait until last frost to move them. I’ve only been at this 3 years so im still learning where to place my jms. For the ones I'm growing out i give full sun but everything else gets partial shade to avoid leaf scorch.

 

[glass_shark]

Good advice! I have kept the windows on the side open for some airflow but keeping it zipped (because I will forget to close it and im scared some critter might move in there if I leave it open) but as it gets warmer I'll probably open it during the day. I wonder in the summer months if itll even be worth keeping the greenhouse up, or if it'll get too hot in there for anything but tropicals. I also have some tiny maples that I'm not sure what to do with, they dry out very easily so I should probably just keep them in there right?

 

[HamburgerTrain]

Good advice! I have kept the windows on the side open for some airflow but keeping it zipped (because I will forget to close it and im scared some critter might move in there if I leave it open) but as it gets warmer I'll probably open it during the day. I wonder in the summer months if itll even be worth keeping the greenhouse up, or if it'll get too hot in there for anything but tropicals. I also have some tiny maples that I'm not sure what to do with, they dry out very easily so I should probably just keep them in there right?

Its a lot more humid and hotter where you are, speaking from experience. I don’t keep anything in mine in the summer. I was thinking of taking the vinyl off the frame and covering it in shade cloth.
For tiny trees I started out putting them on top of the soil of larger trees in nursery cans or grow boxes. I have so many now that i keep them together in larger containers filled with pumice, bigger pots, anderson flat, etc.
I have a large conifer in my backyard that partially shades a large portion of the yard. All the delicates go under there in the summer.

 

[glass_shark]

The shade cloth is a great idea! I get a nice dappled sun some of the day, full sun the rest of the day, but I did run into leaf scorch last summer here. That might be a better option for controlling the amount of shade i get, its a little unpredictable throughout the season

 

[leatherback]

You are overthinking. If japanese maples can grow in the landscape where you are without problems, they can be outside without big problems. Only if you get really cold winters (No idea what your climate is) do you consider protecting. But up to -10C / 15F maples are typically hardy if sheltered from wind and sun, sitting on the ground.

By putting them in a greenhouse you have made them more sensitive to frost as they have not had normal winter weather. So now you need to protect them from frost. But get rid of the greenhouse as soon as frostrisk is gone.

 

[Piedmont Bonsai]

I live near where you are. Your maples need to be out in full sun right now.

 

[HamburgerTrain]

You are overthinking. If japanese maples can grow in the landscape where you are without problems, they can be outside without big problems. Only if you get really cold winters (No idea what your climate is) do you consider protecting. But up to -10C / 15F maples are typically hardy if sheltered from wind and sun, sitting on the ground.

By putting them in a greenhouse you have made them more sensitive to frost as they have not had normal winter weather. So now you need to protect them from frost. But get rid of the greenhouse as soon as frostrisk is gone.

A tree in the ground is more hardy than a tree in a small pot.
Jms can definitely die if they get hit with frost this time of year at bud break or with fresh leaves. Also you risk losing fine branching.
I lost several red leaf maples in late winter early spring from late frost.

 

[leatherback]

A tree in the ground is more hardy than a tree in a small pot.

Oh wow, now that is news..

ms can definitely die if they get hit with frost this time of year at bud break or with fresh leaves.

There is frost and there is frost.

I have had JM in full leaf get -2, -3c dips (~ 29F) in early spring. They handle this perfectly well if it is just an overnight few hour dip.
If JM are kept outside over winter (Which is fine in a zone 7) they normally are not at great risk under normal spring conditions. If you do not allow them to go fully dormant, such as by placing them in a warm overwintering location, it is a different story.

As said:

By putting them in a greenhouse you have made them more sensitive to frost as they have not had normal winter weather. So now you need to protect them from frost.

 

[Paradox]

My maples go in the cold frame up here in NY. Most of the water winter, the cold frame stays open on top unless the temperatures are going to be below 25-30.

Sometimes it gets colder than predicted and i didn't cover the cold frame. They got temps around 27 degrees regularly this winter. They are on the ground and against the foundation of my house so they probably didn't get the full brunt of 27 degrees those nights.

I don't forsee that as a problem. I think we tend to baby our trees too much sometimes.

I used to keep them in my attached garage. It stayed too warm and they leafed out too early. I lost at least one maple because I put it outside too soon from those conditions and the leaves shriveled in the cold wind. Tree didn't recover. After that, I built the cold frame and have not had these problems since.