I’m in love with our attached greenhouse. When we found our off-grid homestead, I’ll admit the greenhouse was one of the main selling points.
Finally, a convenient place for starting all my seedlings for our summer garden! I had no idea that the greenhouse would become such a part of our day-to-day lives, and truly essential for running our homestead.
Benefits of an Attached Greenhouse
The main benefit actually has nothing to do with plants or gardening. It has to do with warmth.
If it’s sunny, it doesn’t matter how cold it is outside, the greenhouse will be cooking. We have a door that leads from the greenhouse into our kitchen, and three full wall height windows that we can open to let the warmth into the house.
Some years, if it’s sunny enough, we can go several weeks mid-winter without running any heat. That’s January…in Vermont…with no added heat.
Beyond physical warmth, there’s also the psychological benefit. When it’s -20 outside, and has been for seemingly forever, there’s nothing better than stepping “outside” into a 90-degree greenhouse in a tank top to enjoy a cup of tea.
The way our greenhouse is built, it’s more of an extra room than a simple greenhouse, which really expands the options in our 1 room cabin style home.
Starting Seeds in an Attached Greenhouse
While I assumed that the greenhouse would be the perfect place to start my seedlings, it’s actually not as great as you might think. Many seeds need to be started indoors in late winter to get a headstart on our very short Vermont growing season. That means starting some seeds as early as February.
It’s true, the greenhouse is warm on sunny days, but it doesn’t keep the constant warm temperatures that seeds need to germinate. Cold isn’t the only problem.
When the sun does come out, the greenhouse can rapidly heat to 100 degrees or more if you’re not watching, even if it’s below zero outside. With the cold outside temps, all the vents are closed so it could be dangerous for fragile seedlings.
Heavy winter snows can also cover the glass and block out sunlight, and even without snow, the days are remarkably short in late winter.
Pests are also a huge problem. Since the temperatures stayed relatively warm over the winter, and heat up quickly in the spring, pests are quick to come out of hibernation and attack tender seedlings. Aphids have been a particular problem, and they’ll destroy or stunt seedlings.
With all those considerations in mind, we do some of our earliest seed starting inside the house. For tender seeds, it’s best to think of the attached greenhouse as one giant cold frame. The greenhouse can be used to grow out seedlings and help harden them off before planting, but we don’t count on it for seed starting.
Paved Floor or Dirt Floor Greenhouse
I love the idea of planting right in the dirt, but practically speaking I’m glad our greenhouse has a floor. Managing extra soil moisture against our basement could turn into a nightmare, not to mention a disruption in the freeze/thaw cycle of the ground right against the foundation.
Having a real floor in the greenhouse also makes it seem more like a living space.
Greenhouse Moisture Issues & Drainage
Whether you have a paved floor or a dirt floor, drainage will be an issue. Ours has a drain in the floor at one end that shunts water about 100 feet away from the house into a runoff ditch.
As far as the siding of your house goes, I’d still consider the inside of the greenhouse to be an “outdoor” space and you should weatherproof your house accordingly. Ours has a vapor barrier under cedar V-groove planking that gives it a bit of an interior look, but much of the resilience of an exterior finish.
Be sure to use flashing to keep any water running down the side of your house from infiltrating the attachment point at the top of the greenhouse. Our greenhouse uses a rubberized barrier that slips up under the cedar siding above the greenhouse and flaps over the top edge of the greenhouse to allow any water to just keep flowing down the outside.
Roof Angles & Snow Load
Since our greenhouse has a significant slope, snow load isn’t as much of an issue as you might think. We take a large push broom out and sweep it off, which allows sunlight to warm the glass. That warmth melts any last remaining bits of snow off and helps keep the attached solar panels free of snow.
The main issue is ice. The roof above the greenhouse has an icebreaker bar to break up falling roof ice as it comes down to help protect the greenhouse.
We haven’t had any issues yet with broken glass or panels, even with substantial ice. It is a bit terrifying when the ice does fall through. Such a crash, and there’s a part of me that always worries.
Incorporating Solar Panels into an Attached Greenhouse
The solar panels at the top of our greenhouse just make sense. In the winter months, the sun angle is lower and most of the light directly impacts the glass. The solar panels don’t shade the greenhouse at all.
In the summer, when the sun is higher in our northern latitude, the solar panels shade the greenhouse and the windows on the side of the house, which keeps everything nice and cool even in the heat of the day.
The greenhouse environment under the panels also means that the solar panels melt out quickly after snowstorms. We have other solar panels attached to our shop/garage and they’re very high up on a steep roof.
When we have an ice storm, there’s no way to clear those panels and they can remain useless for weeks at a time. That’s not the case with our greenhouse panels, which provide a much more reliable source of off-grid electricity.
Summer Heat Considerations
A greenhouse is designed to trap heat, and when the days are long and warm, too much heat can be a problem. Our greenhouse has a door on each end that we leave open all summer long.
In the late spring, we open the two full-length vents, one at the top of the greenhouse and the other along the south side. Those vents are operated by antique hand-crank mechanisms, which means we’re not dependent on electricity for venting.
Manual venting has its benefits off-grid since you’re not dependent on power or computers. It also has downsides. We have to plan ahead if we’re leaving the house and vent the greenhouse if we think it might be sunny later. It doesn’t take more than 20 minutes or so of direct summer sun to bring temperatures up to dangerous levels for the plants in a fully closed greenhouse.
There are many times I wish we had an automated vent attached to a temperature sensor. In an ideal situation, install something automated, but have manual backups.
Greenhouse Pest Problems
Continuously warm temperatures mean that once pests take hold, they can really rage out of hand. While ladybugs go to bed for the winter, aphids will keep right on going if temperatures are favorable and they have a food source.
We originally grew winter greens such as arugula, claytonia and tatsoi in the greenhouse to supply our family all winter long. It was great until warmer temperatures in March arrived.
The aphids woke up and devastated the greens. We tried just about every organic control on the books, but the greens were still painted with aphids and eventually died.
We’ve since changed our plan.
The only year-round crops we grow in the greenhouse are herbs, which have their own defenses. We never have pest problems on rosemary, oregano, tulsi and thyme.
Beyond pests that impact the plants, we also have pests that impact our house. Wasps are a significant problem.
They love the warm environment and it’s a constant battle to keep them from building nests in the eves inside the greenhouse. We hang a non-toxic sight lure wasp trap and we have to change it out monthly in warm weather because it becomes so covered in wasps.
The biggest problem is keeping the wasps out of the house when we’re trying to use the greenhouse to heat the house in the spring. Be sure to install good screens on any windows that lead to the greenhouse, because pest pressure is actually higher inside the greenhouse as compared to the rest of the outdoors.
I’ve reread this a few times, so I apologize if I did actually miss this, but what orientation is the sunroom? Does it face South?
Also, you mention having your lemon tree in there in May. Do you bring it inside during the winter, or can it manage overnight? I ask because I’m from CA but moving to New England next year (my husband is from there….) and I’m trying to figure out how I can continue to have my Meyer Lemons!
Hi, this was a great article, I’m in NH and hoping to build a new barn with a greenhouse attached. Did you build yours yourselves? Where did you get your material or was it a kit?
I’m also wondering if your greenhouse is south-facing. I’ve been thinking of putting a greenhouse on the south side of our house in Northern VT, and wondering if you are able to leave your plants in the greenhouse (thinking citrus, hibiscus, etc.) through the winter.
Ours is south facing, but we actually lost our citrus trees in a particularly cold snap leaving them out there. It’s single pane glass, and the top and doors don’t seal as well as they should. In a well sealed, double paned greenhouse you’d likely have better luck. During the coldest periods we now bring the citrus trees in, but we were able to overwinter rosemary bush out there for 3 years.
I am thinking off an attached greenhouse in VT, so this is super helpful! Is you floor just pavers, or are they over slab?
It’s over slab because it was put in at the same time as the house foundation, so it’s attached to the wall of our full basement. They did a lot of pre-work around the outside, and there’s foam board and god knows what buried all around to help guard against frost heaves. (I know because I tried to plant a strip of short herbs right in front of the glass, and there’s foam board under the grass there.
Thanks for a great blog post. This is so helpful! Very well done and exactly what I wanted to know.
Great blog. If you ever get a free moment check out an arduino tutorial on youtube. It’s a bit daunting at first but you can learn to make automated controls for anything for just a few dollars.
Look for automated greenhouse vents powered with wax or oil that expands at it heats – they will open and close windows and doors anytime it gets too hot in there. As for wasps – blow air into a brown paper bag and hang it up inside the greenhouse. Wasps see it and think that other wasps have built a nest in there, which will keep most of them out. Thanks for a great blog 🙂
I have had nearly identical experiences in my sunroom right down to the ahpids! I live in northern Washington and mainly use our sunroom for home heating. Nice idea using solar panels for shade.
What an informative article, Thank you ! PS – would love to see the interior layout of your beautiful home.
It’d be pretty simple. Downstairs is all one room, then a half loft over it for the 2nd story, with a ladder up to a small turret at the top.
Thank you! I am considering the same thing myself, but making it part of a tiny home that I am designing. Is moisture an issue at all? If so, how do you deal with it? I am experimenting with hydroponics now and hope by doing so, I can avoid some or all of the pest issues you mentioned.
We haven’t had moisture issues, but there’s a good vapor barrier and cedar shiplap siding all along where the greenhouse attachest to the side of the house.
IT’s beautiful! Did you build it yourself or have it built? DO you have the plans?We’re gong to be moving and I’ve had a sunroom here; I’ll need to have one on the new place.
Yours is LOVELY!
I am considering a freestanding greenhouse, as I am battling birds, vole, moles, rats, etc.
HoweverI am concerned with pollination or lack of….
I grow tomatoes, zuccini, yellow crookneck squash.
have not decided what else to grow in green house.
I easily grow herbs out doors now.
I was hoping a greenhouse would solve all problems… not
create new ones (pests)
thanks for your article. I did not realize heat would be such a problem to control.
I would build screened, maual opening vents, but did not think temp would require contant monitoring 🙁
even to require an temperature sensor operated vent or fan?
Barrie in Brandon
Something I would add here for everyone’s knowledge is heat operated controllers for venting. They use a wax filled piston and leverage, so some design considerations are needed. My most pondered concern would be depending on your greenhouse height, where exactly to place it/them so you don’t accidentally over-ventilate when you actually want to trap that heat. Also, a cold sink can possibly help too.
Love your site! I am also planning to put an attached greenhouse on our future home in western MA. Hard to tell from the photos, is yours all glass or are there any solid/insulated parts of it (such as a knee wall on the south side or parts of the east/west walls)? Can’t wait to have my own winter refuge!
Mine is glass all the way down to the floor on the south side.
Great website! Planning to make an attached, south facing greenhouse with all the bells and whistles however I have a few concerns.
First the heat in the winter months, warming up the house since it is attached to the greenhouse. I am not sure how much a good, automated ventilation system would help. Oh, and I am in South Australia, summer quite sunny and hot.
The other issue is that my location is elevated, my living room door which would be the access to the green house is about a meter high from the ground. I currently have an old timber deck there which is not being used. So, I was thinking to make the floor of the greenhouse elevated in level with the door (as the timber deck is now) however I was thinking to keep the timber planks with gap in between. This would help with the air circulation/venting I guess however I am a bit afraid of pests. What do you think?
I definitely think that the gaps would encourage pests even more which can already be an issue and it would be difficult to control the ventilation.
Hi would you please share the dimensions of your greenhouse?
Thanks in advance!
Thanks Ashley for the great pro/cons blog. I’m over in NH, and debating an attached greenhouse to our shed, which isn’t really the same as one cozied up to a nice warm house. I’m debating the foundation though, and thinking about erring on the side of insulation (like a mini house with lots of windows) vs. a true passive solar due to temps in the winter.
Do you know if your greenhouse foundation was built below the frost line at all?
Ours was built below the frost line (at least in theory), and insulated with blue board all around below the soil, but we’ve had problems with some minor heaving anyway. Clearly, it isn’t quite deep enough…
I’m in Southwest Washington state and my best option of my needs is a north side sunroom. I can see that most of it is shaded in the winter but I have detached heated sunrooms for plants. This room will be for extra space and pet area. I intend to lay a 4′ cement slab and knee height brick as well as a brick fireplace (they did explain I needed to make sure the heat from the fireplace will be a good distance from the glass) and 3 drains since it’s long and I want to put a spa in there as well. I know in my regular greenhouse (I keep duck and geese) I have pests but only the ones they can’t reach… Do you think I’ll be facing pest problems in the one I’m considering building on the northside? Or are there other problems with building on the northside???
The biggest issue will be the lack of sunlight in that space which will keep it very cool. If it’s on a concrete slab, I don’t imagine that the pests will be much of an issue but it depends on how well everything is sealed up.
This Vermont Mama is so thankful for your posts! Every time I stumble on one on Pinterest I’m like ooh another great relevant blog, then I realize its you. If you ever want a friend or two from southern Vermont to connect with, I’m here for it! We clearly think alike. I appreciate your a few steps ahead of my skill and knowledge level at all times too. Thanks for sharing so I can prevent some possible pit falls! I have been dreaming of an indoor greenhouse like this and never thought of some of the things you mentioned that are easiest to learn by experience.
Ann Marie Barrier
Thank you so much for your information about an attached greenhouse. Contemplating the best avenue for our house.
You’re very welcome.