Questions for Michigan/Northern Growers, or An

[Alex DeRuiter]

**Edit: Pardon the poorly titled thread...meant to say "or Anyone willing to contribute to the discussion."

Hey everyone, I have a few questions about greenhouses in general and about the growing season in Michigan.

First, greenhouses: I've been experimenting a little bit but I'm not experienced enough to make a decent one. I bought one early last year which is pretty much a cheap, plastic frame and some green plastic sheeting. Here it is on Amazon. I'd like to eventually build my own with better materials but until then, this may or may not have to suffice. . . .

Now, something I noticed throughout this season is that with the poor ventilation, it can get very hot in this greenhouse. I ended up cutting a flap in the back for air flow, but it's currently taped. I currently have some conifers in there just for weather protection, but I was wondering if this is dangerous because of the higher temperatures in the sun and the low temperatures at night. Can anyone shed light on this in particular? Should I just take them out if the greenhouse and put them in the garage with my deciduous trees?

I was also wondering...I see people with nice hand-made greenhouses, but I would imagine they experience the same problem (in regards to the heat generated by sunlight). Is it only ventilation that solves this?

Second question: Michigan growing season. I've seen a few posts on here where people are ALREADY in repotting season (grrrrrrrr), and I've seen a few people say that growing in Michigan is extremely limiting as far as tree development goes. My questions are: Are there any species that grow more vigorously in the northern states that one could develop faster/better than more temperate trees? Are there ways I could create a better climate to grow temperate trees longer?

In regards to that second question, I think I remember seeing Judy, one of the board members, saying something about adding bottom heat to trees in her greenhouse in hopes that it would provide a longer growing season for her trees. Is this a common practice for northern growers? Would one need a house-attached greenhouse to achieve such a thing?

Any information would be much appreciated. Thanks, everyone.

 

[JudyB]

Ok, I think I can help, having been through all this myself. I first bought a plexi lean to greenhouse kit and put it on the end of a shed we built ourselves. We did a triple wall roof. My original plan was for winter vegees and trees. Then I started doing more trees. Goodbye vegees... But the plexi and triple wall allowed too much heat buildup. I did a solar vent, but it wasn't enough. So a few years ago we tore it all down and started from scratch.

Built a frame greenhouse that has half walls, and a real roof. The upper half of the side walls, are solexx, it's a opaque material that you can get in rolls, and is super easy to work with. That has cut down on the solar heat issue. This is a big problem, as you'll have plants that need to stay in dormancy try to break out during the winter.

I have a small heater with a blower fan for heat, and a exhaust fan for cooling. Both are hooked up to a thermostat that have choices for high and low temps. On the opposite end of the fan, we installed electric louvers so that when the fan turns on, the louvers open and cold air is pulled through the house. I do have some windows in this greenhouse, but with all the solexx, and the actual roof, I haven't had any problems with too much sun. If I did, I'd make some shade cloth blinds for them. I'll attach some photos, if you have any questions, let me know. We are going backpacking in SoCal for the next week or so, so if I don't get right back to you - I will eventually...

 

[JudyB]

Oops, they are a bit out of order, but you get the idea. Here is the finished project. I can also use this as a curing house during the summer and fall for sweet potatoes and anything that needs to be dried in warm air.

As you see the blue things on the benches are heat mats. I use thermostats to control them and keep them around 35, at least on the cold side. I still want dormancy, but don't need to keep the trees in the house much above freezing. (the heater is set for around 33 and I usually am able to keep the air temps between 28 and 40 in there ) The warm heat mat side, I keep a bit above that, and push it higher at the beginning and end of winter. This keeps the trees warmer longer, and starts them up earlier. I don't do too much of this, still experimenting a bit with this season extending idea. Part of the trouble you can have is giving them enough sun after you start them early... But I do have lights in this house, and some glass. I also would suggest cool mist humidifiers, I have one for each side, and it works wonderfully, I have them on cheap light timers, and have them on for 30 mins, 4 times in 24 hours.

It just takes a bit of work to get something that can work for your particular types of trees...
But it's been well worth the investment for me, I haven't lost a tree since we built this.

Just remember whenever you get jealous of what you can't grow in MI, that you CAN grow larch, white pines, and Japnese maples there. Lots of places have trouble with these as it's not cool enough...

 

[rockm]

Before you pick up a hammer and level, it would be best to consider what you want a greenhouse FOR. If you want to keep tropicals, a full-on greenhouse is the way to go. If you're looking to overwinter temperate trees, think again. Greenhouses are NOT a great temperate tree overwintering facility--at least without some thoughtful--and sometimes extensive-- modifications as Judy points out. You can't really overwinter and grow tropicals at the same time.

As for the repotting practices of others, don't dwell on it. It's always greener on the other side of the fence, climatewise. The folks that are repotting now can't grow colder weather species, like larch (Japanese or American), spruce, apples, or in some cases Japanese maples. Many of those same folks who are repotting now envy more northern climates in the autumn when trees in more Northerly locations get fall colors...

 

[Alex DeRuiter]

Show-off!!

I am e-x-t-r-e-m-e-l-y jealous of your abilities. Seriously, that is impressive. I hope to build something like that some day, but sadly I'm still renting at the moment. Perhaps next year we'll buckle down and buy a house, but until then. . . .

So, do you keep your trees in there until it's safe for them to be outside in spring, and then take them in when temperatures start to drop in the fall? What kind of lights do you have? I'm thinking about making a somewhat large greenhouse, but do you think half walls are a necessity? I've seen Walter Pall's greenhouse (one of them?) on his blog and he has full window panes. I'm wondering if that would be better for making sure the trees get as much light as possible. Then again, I don't know if it's kind of a lesser-of-two-evils thing -- light or heat.

Do you think I should take my trees out of the greenhouse and take them into the garage for winter storage? I have a collection of junipers, pines, a yew and a fir. I'm just worried it'll get too hot in there. I could throw a blanket or sheet over the frame, but do you think that would work?

Was it hard to program everything to timers and thermometers? I've never done anything like that but it seems like a simple task -- luckily I'm technologically inclined, so that'll be a lot easier than the actual building of the greenhouse for me.

I've been sticking mostly to maples, but I ventured out a little bit to experiment. After I weeded through a lot of the trees I knew had no future, I acquired some stuff I thought might make fun projects. That being said, I'm wondering if half walls/half windows would be best.

Good point about the species that do grow...I'm still sad I have about half a growing season in comparison to some. lol -- but oh well, that's just the way it is. Thank you so much for your post. I hope I can make something of that caliber some day.

 

[Alex DeRuiter]

Rockm, good points. I really am glad that I have the ability to grow such species.

As for what I plan to use the greenhouse for, it's just for overwintering temperate trees. I do have tropicals, but I keep them indoors under some lights. If I do end up building something similar to Judy's, I might make two rooms and heat one of them for the tropicals. Currently I'm just sticking my deciduous trees in an unheated garage and keeping the conifers in the greenhouse...but by the looks of it I should take those out and throw them in the garage as well.

I'll have to wait at least a few years before I can build a nice one, though. I'm still renting, but I was thinking about buying a house in the next year or so. We'll see how that goes. I'll be going to a school about 50 miles from my current location, so I'm trying to find something in between the towns. (Sorry for the life story. lol)

 

[Alex DeRuiter]

By the way, Judy, have fun on your trip!

 

[JudyB]

Alex,
Light in the winter is your enemy if you are doing an overwintering house. Trees do not need light in the winter, especially not direct sun. Look at this thread below.
There ARE cheaper and smaller options, this is just what we did, and so we never have to do it over. I only have some glass in there, because I like to get the borderline trees started early, you could do all solexx if you wanted to. I wanted this house, so I could do some borderline trees, stuff that likes it a bit less harsh in the winter... But nothing like trops. Like my hackberry and the tridents, and black pine and crape myrtle. This gives me a couple of zones of cushion. BTW, I'm lucky the old man is into carpentry...

When you do build, keep in mind that there are compositional materials you can use that will help with energy distribution. Like concrete is a great heat sync. It'll collect heat during the day, and release it at night. So I used concrete pavers for the floor. Same with water, it stores heat wonderfully well. I have a rain barrel right inside the greenhouse. I used to heat my old house partly with a solar water type still.

The thermostat is easy, it has dual control hot and cold sides with ac outlets per side that you plug your heater and cooling into. The thermostat just turns on the outlets at whatever you set it at. I also have a wireless thermometer that I keep in there so I can see what the temps are in the greenhouse from inside my house, and then you can adjust accordingly if it has a min. and max. memory function. The heat mats are easy too, you have to get good mats, but especially you want good thermostats, that go down low enough. Most cheap ones only go to 65 or so. Mine go down to 20, I think. They have a probe you can put in one pot.

Trees? I would garage them for this year, better that than to have heat buildup issues, and have them go in and out of dormancy, and kill them. (I killed a lovely pine this way) I don't know about the yew however, it may be too cold in the garage??? Junipers and pines should be good in an unheated garage. Most junipers could probably be good buried in the ground, or covered with mulch outside, but maybe you can't do that where you are. Patience grasshopper, it won't always be like that. You'll get there, it took me years to be able to do it right.

links to stuff.

Thermostat for air temp control - lots of places you can get these, and they're built in Oregon USA! just google
http://www.horticulturesource.com/product_info.php?products_id=761

Heat mats - I like these, they're pretty durable.
http://www.growerssupply.com/farm/supplies/prod1;gs1_seed_germination;pg106148.html

Thermostats for heat mat controls I have a sure stat, like the first one
http://www.littlegreenhouse.com/accessory/controls4.shtml

Thread about winter light and greenhouses on another site - I even learned something here...hope the original posters do not mind.
http://bonsaistudygroup.com/general-discussion/greenhouse-pictures/

sorry this turned into a book!

 

[Bill S]

As Judy mentioned solar heat gain is the trouble you will have in the winter, you want your trees to stay at an even temp. The people I know that build hoop houses for winter protection use an opaque white covering for thier houses, clear lets the sun in and it warms the earth, pots etc., that are darker colors. Darker colored covering will act the same. Additional heat and ventilation may be required depending on what you want to keep, as well as how you can situate the house on your property( does it get sun all day, or shaded for this or that part of the day).

 

[Bill S]

Hoop house in a nut shell

No dimensions, just a how too. Simplified from memory of looking at a couple of these.

lay out 4 x 4" landscape timbers for example, the length you want your hoop house, spread out for width you want.

Drill holes for pvc conduit in timbers every 3-4 feet depending on how much snow you get.

Place pvc conduit( 1/2" to 3/4, maybe 1' depending on how big you want to make the house) in holes on one side of timber and slowly bend conduit over and place the end in the hole on the opposite timber.

Stretch your covering opaque white plastic sheet over the conduits and attach best way you can.

From there it is easy to dress up the edges etc. to make the structure more robust as needed.

This is from seeing an aquaintences hoop house, I may or may not have answers that will pop up from this description, but this is basic construction, alternates are most likely numerous.

 

[Bob]

Nicely done Judy!

 

[Mike423]

I've seen small 'set-up' green houses made of semi transparent plexiglass and metal frame at local hardware stores from around $250-$500 depending on dimensions. They have the dual flap opening vents on the top and you could probably cut a hole in the top and install a vent as well if needed. I was thinking of purchasing one of these green houses next summer so I could have a shot at in-ground growing/overwintering some more sensitive species like Ume so i wouldn't have to wait decades for a decent trunk caliper to form. It would probably work well as far as winter sun protection to make a sun shade cover for it. I was think of doing so by connecting four pieces of pvc pipe together, then using four more pieces as posts and then just draping the sun shade over it.

Anyone with similar experience in this setup have any comments?

-Mike

 

[amkhalid]

This is a very impressive overwintering setup Judy, I am really impressed and wished I had the same!

For me this is logistically and financially out of reach, however, so the simplest solution is to work with natives as much as possible. Larch, Arborvitae, Spruce, Potentilla, Jackpine... all bombproof and potentially world-class. There are times, however, when I wish I could confidently grow tridents, japanese maples, and black pines however

 

[Alex DeRuiter]

Alex,
Light in the winter is your enemy if you are doing an overwintering house. Trees do not need light in the winter, especially not direct sun. Look at this thread below.
There ARE cheaper and smaller options, this is just what we did, and so we never have to do it over. I only have some glass in there, because I like to get the borderline trees started early, you could do all solexx if you wanted to. I wanted this house, so I could do some borderline trees, stuff that likes it a bit less harsh in the winter... But nothing like trops. Like my hackberry and the tridents, and black pine and crape myrtle. This gives me a couple of zones of cushion. BTW, I'm lucky the old man is into carpentry...

When you do build, keep in mind that there are compositional materials you can use that will help with energy distribution. Like concrete is a great heat sync. It'll collect heat during the day, and release it at night. So I used concrete pavers for the floor. Same with water, it stores heat wonderfully well. I have a rain barrel right inside the greenhouse. I used to heat my old house partly with a solar water type still.

The thermostat is easy, it has dual control hot and cold sides with ac outlets per side that you plug your heater and cooling into. The thermostat just turns on the outlets at whatever you set it at. I also have a wireless thermometer that I keep in there so I can see what the temps are in the greenhouse from inside my house, and then you can adjust accordingly if it has a min. and max. memory function. The heat mats are easy too, you have to get good mats, but especially you want good thermostats, that go down low enough. Most cheap ones only go to 65 or so. Mine go down to 20, I think. They have a probe you can put in one pot.

Trees? I would garage them for this year, better that than to have heat buildup issues, and have them go in and out of dormancy, and kill them. (I killed a lovely pine this way) I don't know about the yew however, it may be too cold in the garage??? Junipers and pines should be good in an unheated garage. Most junipers could probably be good buried in the ground, or covered with mulch outside, but maybe you can't do that where you are. Patience grasshopper, it won't always be like that. You'll get there, it took me years to be able to do it right.

links to stuff.

Thermostat for air temp control - lots of places you can get these, and they're built in Oregon USA! just google
http://www.horticulturesource.com/product_info.php?products_id=761

Heat mats - I like these, they're pretty durable.
http://www.growerssupply.com/farm/supplies/prod1;gs1_seed_germination;pg106148.html

Thermostats for heat mat controls I have a sure stat, like the first one
http://www.littlegreenhouse.com/accessory/controls4.shtml

Thread about winter light and greenhouses on another site - I even learned something here...hope the original posters do not mind.
http://bonsaistudygroup.com/general-discussion/greenhouse-pictures/

sorry this turned into a book!

Don't worry, I like books. lol -- thank you for posting all of that.

What you built is particularly nice because it looks like you've created some space to work on your trees as well. I really would like to build something like that eventually. Yeah, I remember reading something about how light can even be damaging to a tree if the temperatures are cold enough...so I just threw all of my trees in the garage this morning. As for the amount of their exposure, it's been probably three or four hours a day...but it's been unseasonably warm this year, so hopefully nothing will die. I'm a bit disappointed in myself for not realizing this earlier. lol -- but "live and learn," I suppose. You should send the old man up here to teach me some stuff. haha

Very, very good point about energy distribution. I didn't even think about using a rain barrel! That's an awesome idea. As for the concrete, I've never poured any and my friend who's into this sort of thing hasn't either, but he suggested having someone come out and pour it for me when I do build one. He said it's relatively inexpensive if you find a good company, so I'm hopeful. But yeah, this is a great plan for when I actually own some property. Maybe I can just get them to include it in the home loan.

How convenient! I didn't even think of having some wireless thermometer so I could check it without going out. I feel like this is all stuff I should've thought about already, but I'm going to play the "I'm-only-three-years-into-this" card. It sounds pretty easy to set up, thankfully. I'll have to run power to my future greenhouse, but that won't be hard. I have a nice digital thermometer in my garage, so I've been checking the min/max every morning to make sure it isn't getting too cold.

Yeah, I figured the garage would be best. We only really use it for storage anyway, so it's not a huge inconvenience. I buried some stuff in the ground last year but it was a huge pain to dig it out, so I figured this'd be a lot easier for me. As for the yew, it looks like this particular one can withstand temps down to zone 4, so I should be okay being in 5b.

Thank you for the encouragement -- I will indeed get there eventually.

Thank you for the links! Those heat mats look awesome, but let's wait for next year's tax season. lol -- I bookmarked everything though, so it'll be revisited.

As Judy mentioned solar heat gain is the trouble you will have in the winter, you want your trees to stay at an even temp. The people I know that build hoop houses for winter protection use an opaque white covering for thier houses, clear lets the sun in and it warms the earth, pots etc., that are darker colors. Darker colored covering will act the same. Additional heat and ventilation may be required depending on what you want to keep, as well as how you can situate the house on your property( does it get sun all day, or shaded for this or that part of the day).

That makes sense -- just like wearing a white t-shirt instead of darker colors in an attempt to keep cool on sunny days. I wish I would've thought about that before keeping the trees in there so long. Luckily it's been a really mild winter anyway, and has been relatively cloudy for the past few weeks...so I'm hoping everything survives. Would I see an indication that they were declining during these months (browning needles or anything), or would I have to wait until spring to see if they push out new growth? As of now everything is still a healthy green, but I'm still a bit concerned.

Thank you for the directions for the hoop house, as well. This would help clear some room in the garage and would localize everything. . . . We shall see.

 

[Bill S]

Hard to say as to the decline, many conifers won't show dead until it's waaaay too late.

The issue is heat more than cold, a few days of sun and mild weather can get some trees thinking spring, then when the cold returns everything that started to move freezes, and gets killed off. The key is to keep a near constant temp., somewhere in the 30 to 45 range, unless you are dealing with material that is less than temperate, then you need heat and ventilation.

 

[Alex DeRuiter]

That makes sense. Welp, I'll let you know how it goes in the spring. Hopefully nothing dies...and yes, I feel a bit foolish saying that. Nevertheless, thanks for the advice and the insight.

Mike, that's my intention as well. I have a couple Ume, but it's mostly maples I'm concerned about. Hopefully I'll be able to get something going to where I can have them growing a bit longer.

 

[davetree]

You can grow trident maple, Japanese maple and black pine easily in Michigan, especially if you are in zone 5. I am in Minnesota in zone 4 and don't have any problems. You just need to winter them correctly. Hell, you could almost grow tridents outside with protection where you are.

 

[Alex DeRuiter]

Yeah, that's what I've been doing -- at least a few planted in the ground and the rest in pots. What I'm jealous about is the length of the growing season...those bastards down south! ;-p

 

[davetree]

They do have a longer growing season but they also have much hotter temps in the summer, which can slow or stop growth in many species. Bottom line - you can get a lot of growth out your short season if you push your plants.

 

[Alex DeRuiter]

Touché, good sir...touché. I hadn't thought for a second about the disadvantages to the high temperatures. Thanks for pointing that out