My temperatures and humidity are completely whack.
I was originally going to add just a section of shade cloth for some indirect light plants, but it's way too hot for just that. For heat I've heard raising the shade cloth off the surface to reduce heat transfer will help (any tips for strong winds?). I also expect I could use more shade cloth to cover the late afternoon sun. And the window is on an automatic opener with a ground fan running high most of the day.
My thing is the low temperatures are pretty in-line with the daily forecasted lows, so there's really no retention overnight for temperature or humidity. The roof is double-walled polycarbonate but the sides are some other single-layer plastic. Even if I get the highs figured out I'm worried I won't be able to trust this enclosure for the Fall evenings.
Is this just a poor greenhouse or are there things I can do to still make this work?
PS: I live in Colorado and our temp range has been roughly 80/55° during this time window
by YesPleaseIdLoveTo
12 Comments
That’s just what the humidity does even outside. I remember tracking it outside when I had some cannabis plants vegging outside in a courtyard and being amazed the swings that happen every 24 hours and the plants were quite happy. For the temps, do shade cloth and set up exhaust fans like this.
https://www.acfgreenhouses.com/greenhouse-fan-calculator.aspx
Go over with your fan ratings, I suspect a lot of cheap greenhouse exhaust fans have bogus ratings.
For warmth in fall you will just have to have a small heater.
So I would start with some sort of thermal mass that will lessen the valleys and lower the peak temps.
Second you will want to have air movement so an intake and outlet [fan](https://ilivingusa.com/products/ilg8sf10v-st) or additional [automatic window openers.](https://www.amazon.com/UMISKY-Automatic-Greenhouse-Sensitive-Greenhouses/dp/B08JCFSRJ4/ref=asc_df_B08JCFSRJ4?mcid=f726a7e9ef943a6ebbc0cfa457a262e4&hvocijid=5255492685002670698-B08JCFSRJ4-&hvexpln=73&tag=hyprod-20&linkCode=df0&hvadid=721245378154&hvpos=&hvnetw=g&hvrand=5255492685002670698&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9016882&hvtargid=pla-2281435179098&th=1) I run the fan I linked in a larger size and it keeps the air around 90-100 when set for 88F. Prior to that with just internal air movement, I was easily seeing 120-130F with an external ambient of 90F.
Another way would be to replace a couple panels with wire mesh if you’re worried about pests.
Where I am in 6B many growers don’t even have the end walls on their hoop houses.
My last suggestion would a swamp cooler like [this](https://www.theplayalabs.com/swamp-cooler) setup on a timer for the heat of the day should further lower the peaks. I’m unfortunately in way too humid of an area for a swamp cooler to work.
There is a learning curve with greenhouses and I am going to make an assumption, but it seems to me that the smaller structures are harder to regulate because it takes so little to throw them out of equilibrium.
That heat is totally expected without any proper ventilation. Have you sat in a car baking in the sun with only one window 6″ open? That’s what you have but with way more sun getting in.
Opening the door will help so the hot air can rise out the top and bring cool air in but it would be a lot better with 2 vents on the roof and 2 at the bottom. As the hot air rises the cool air can be sucked in through the bottom vents. [Example here](https://www.hortidaily.com/remote/https/agfstorage.blob.core.windows.net/misc/HD_com/2020/08/25/dr_greenhouse2.jpg?preset=ContentCustom)
In regards to the night time temps, those flimsy single pane panels do basically nothing for insulation and you don’t have anything inside to radiate heat after the sun goes down. Even with twin wall poly you’re going to drop down to ambient temps pretty quickly. You will need a small heater in the early spring/late fall if you want to maintain warmer temps at night. Twin wall will help reduce heating costs but that might not be easy to retrofit and any gaps letting in cool air from outside will greatly reduce their effectiveness.
With this type of GH, night time temps will mirror outside temp….. these walls offer NO insulation the temps go down when the sun goes down. A heater will help keep might tmeps up, but will be usually when it gets winter time cold
ANY green house is basically a “locked car with a dog in it” when the sun is up….. with out air movement and ventilation it will be am oven. If it has vents open them….if not, open the door but a box fan on teh ground pushing cool air IN so hot air will be forced out
The classic solar oven. If you want to use it as anything more than a slight season extender you’re going to need to actively heat or cool it. This means heaters and exhaust fans to curb the extremes.
What system/app are you using to track temp and humidity?
A big fan with a $5 timer would do wonders
How hot does that concrete get? That might be part of the heat issue.
You need more air flow and misters lowered my greenhouse by 10 degrees alone.
Looking kinda like my greenhouse lol
Greenhouses are awesome but I could only use them from seed room to greenhouse to outside perfectly but long term is a different animal and a lot of time to keep stuff from frying , good luck
Well, short term maybe try reflective insulation on one or two of the walls. Get it as thick as you can, and experiment with which walls work best for you.
Short/medium term, you’ll need active cooling/ heating measures.
long term, you’ll want more greenhouses adjacent to each other, or just a bigger one in general. More volume inside the GH means more temperature buffer, so peaks and low temps happen more slowly