Do I HAVE to have a fan to vent my greenhouse?

[Betho]

Hi, this is my first post

Okay so here's what I'm looking at - I have about 18 door-sized glass panels that I am going to make into a greenhouse. I'm trying to do this with as little out of pocket as possible.

SO, is it possible to vent a greenhouse without a fan or something? I don't know what's best.

Here's what I'm dealing with - zone 7, pacific northwest, yard is 90% shaded and greenhouse will be in the one spot that is not 100% shaded. Not sure what summertime airflow is like, since we just moved here in Nov.

So can I just build in some windows that I can open on the sides? I've got a couple of those, even some of the smaller sliding windows that come on car toppers. That for the top, and should I do something similar for bottom vents?

Forgive me if this is a very basic question, but my searching skills are not turning up what I'm looking for, either here or on Google

Now I just gotta figure out a way to attach the chicken coop for passive heating in the winter... lol

 

[Rozzie]

I think you'll end up cooking your plants without it.

Also, remember that there may be times you are not home to open and close windows yourself.

I'm hunting for greenhouse ideas myself. Sites I've read suggest that a lot of people new to greenhouses or looking to economize are tempted to go without a fan but that this is a BAD mistake...

Take my advice on this topic for what it's worth: I'm researching greenhouse ideas but have not ever had one myself, so my experience in this area is nil.

 

[lesa]

Welcome! Welcome! I am just in the process of setting up and using my green house for the first time. The one thing I can tell you, is that it is way too hot in there, right now (and my air temps are in the 30's) to grow anything!!! I couldn't believe how fast it got burning hot in there. I am going to try, what you are suggesting. I will have two half windows that will be vented. I can also remove some glass from the doors that I am using.
In the back of my mind, I am thinking I am going to have to use a fan. If it is this hot already, what will happen when the air temps are in the 60's??
Since you have a little shade, perhaps the issue won't be so bad, for you. I say, build it- put a thermometer in there, and see what happens!
Good luck!

 

[wsmoak]

We just had a small (10x20) shed/greenhouse combo built, and it gets pretty warm in there. On a bright sunny day you're going to need some ventilation or you'll end up killing the plants. Hardly the point of a greenhouse, right?

Now... I could also use some suggestions for fans with thermostats, if anyone has a favorite!

-Wendy

 

[thistlebloom]

Welcome Betho! I'm sure you'll get good advice here, there's a lot of green house growers on this forum.

Wow Lesa, your green house sounds like it must really do a good job of absorbing the sun!

 

[chris09]

Do you know the style of greenhouse that you are going to build?
How big of a greenhouse are you going build (length - width - height)?
How much air flow is in the area where you are planing to put your greenhouse?

These are questions that will help in the determining on what you may or may not need as for ventilation.

Chris

 

[patandchickens]

The main problem with not having a fan is that you will need instead to have a VERY LARGE amount of openable passive-air-exchange vents.

If you have nothing to do with your life other than sit with the greenhouse all day every day and open/close things as the weather requires, this may be feasible.

If however you are silly enough to have a job, or even just other things to do around the house and sometimes want to go out for four or six hours to run errands, you end up needing to invest in *a lot of* thermostatically-controlled vent lifters, which are not real cheap, and still may or may not have enough.

Even WITH thermostatically controlled vent fans, you will have to do quite a lot of experimenting and learning-from-doing in order to figure out how to get your greenhouse behaving the way you want... without 'em, it will be *much much* harder.

One thing that helps a lot is to cram as much thermal ballast into the greenhouse as you possibly can -- water has better thermal capacity than anything else, tho sand/rock/concrete are useful too, especially where containers of water are not feasible. However this will at best help with temps in the lower third (or so) of the greenhouse, so if you are going to have benches or hanging baskets or tall plants, you will still have rapid-overheating problems up there. (And often down near the thermal ballast too, it just makes things *better* down there, and helps keep greenhouse temps up a bit for the first half of the night)

Just sayin', good luck, have fun,

Pat

 

[digitS']

. . . pacific northwest, yard is 90% shaded and greenhouse will be in the one spot that is not 100% shaded. . .

Welcome to TEG, Betho !

Are you saying that you only have sunlight on that spot for about 10% of the day?

PNW, not a lot of sunny days, altho' that zone 7 designation makes it sound like you may have a few hills between you and the coast . . .

Steve

 

[Collector]

Betho welcome to TEG. Good luck with your greenhouse project!

 

[dickiebird]

This is a very hard question to answer in your situation since you are not sure of the wind patern in you area.

With my setup I usually just open the front doors and get enough circulation so it hardly ever gets unbearable in there.

A few time I have opened the roof vents but not very often.

THANX RICH