From

Location

Message

Date Posted

Ontario

It looks like my plant is coming out in the next week or 2 which means 2025 season prep is starting!
I found an old greenhouse frame for cheap recently, so I figured I'd buy it but now that I'm looking at putting it up I've got questions and since we're not doing normal things, most greenhouse info doesn't apply here.

1st: do you take off the plastic in the summer, if so when? I know that this is subjective and highly reliant on the local weather patterns, but is it normal practice to leave plastic on the greenhouse all summer or do you remove it over the hot months (basically like 90° temps)?

2nd:How important are fans for ventilation? I understand how important ventilation is to maintain dry leaves and to keep fresh air for photosynthesis and all that, but some stuff says to use fans for air flow and others seem satisfied with just rolling up the sides of the greenhouse a few feet.

3rd: how important is disease and fungal prevention comparative to outdoors? I've read that it can be worse in greenhouses, but we also don't hear about greenhouse growers having seasons ended by disease, perhaps that's due to preventative measures they all use, I don't know. I know powdery mildew ended this season for me, so I know I need to be wary of that next year, will that get heightened in a greenhouse? Will I need to be more aggressive with my preventative measures?

Also, how thick of plastic do you use? I would love some 12 mill plastic for the warmth but it also costs a lot and is very heavy to remove, I know 6 mill is most common, but thats for normal greenhouses, do we use something thicker more commonly for giants?

I'm sure I'll be able to talk to at least 1 grower in person this fall, but there's not many who utilize full size greenhouses near me, so I figured I'd ask here for more information and opinions.

9/7/2024 5:44:00 PM

Eugene,OR

1. Roll up your sides in the summer. 2. Fans & ventilation are very important. 3 Everything that can end your season can happen much faster in a greenhouse than outside. Good things happen faster too.Greenhouses give you the ability to control your environment, which is a huge advantage…but you have to constantly be on top of things, or you will be screwed!

9/7/2024 10:48:19 PM

Grittyville, WA

I dont know if 12 mil would provide much benefit over 6 mil. Generally if you want serious insulation then you'd get two sheets, and create an airspace between them. I haven't seen anyone on here do that, but with a setup like that (and some grow lights and/or heat pump in the ground) you could almost grow year-round. I probably cant give any truly good advice. I dont know your climate or your exact goals and I'm no expert on greenhouses, so this is more idle chatter than real advice!

[Last edit: 09/08/24 12:32:57 AM]

9/8/2024 12:31:29 AM

Ontario

Alright vineman thanks. I'll definitely look into what I can do for the ventilation aspect. I'm not running actually electrical out there so I'm limited to what I can run extension cords for so I'll see what I can do.

Also, you've got a good point about the 12 mil plastic. I think I saw Josiah Brandt do it where he had like a leaf blower blowing air between 2 sheets of plastic he put up. Maybe I'll try and figure that out. Not sure how the wiggle wire would work then...

9/8/2024 6:57:05 AM

Syracuse, NY

It'd be cool for an adventurous spirit to re-vitalize my infatuation with Floating Row Cover from like 2004/2005.
NO MORE worries about ventilation (I have cut 'gills' into the fabric at the top, anyway), as it is a breathable fabric, probably could help stop hail damage (?), insects would be minimal and it's available in MANY thicknesses and easily cut through, is repairable-somewhat and what I consider to be really cheap for what it does.
*One MUST be really careful to order it THICK enough to avoid tears, which are EASILY avoided by having NO sharp edges, anywhere.* It's the SHIPPING nowadays that keeps me from building a similar FRC GH and ordering a 40-foot by 300-foot roll, like the one I had trucked to a distribution center and had to bring home on my pumpkin trailer, lol! I MASSSIVELY tore it whilst unrolling it and only had half of my depicted greenhouse covered, butt it was a wondrous experience and I long for it again. Whatever. It'd be a neat thing to try. As soon as I put a FRC GH on a plant, it takes off like I've never seen, I swear!
No electricity needed; If torn, another piece could go over that section and it does last the whole season, for me, anyway.
I am using both 1-year-old and new material this year and it is a deer/pest deterrent as well. It may be called Pro-19 or .55 oz./square yard
eric g

http://www.bigpumpkins.com/Diary/DiaryViewOne.asp?eid=51338

http://www.bigpumpkins.com/Diary/DiaryViewOne.asp?eid=40019

[Last edit: 09/08/24 10:07:12 PM]

9/8/2024 9:51:11 PM

Bethlehem CT

If you are looking for a greenhouse with better insulation against frost and freezing temps. Most greenhouses that are heated use a double layer of plastic that is inflated. THey sell kits to do this. You can do some research and figure out if that is something you want to do. https://www.bootstrapfarmer.com/blogs/building-a-greenhouse/double-layer-inflation-kits

I am not sure two layers will be necessary if all your trying to do is grow a giant pumpkin. A single layer of plastic will get you about 4- 5 degrees fahrenheit of frost protection, An inflated double layer house will get you about 8 degrees of frost protection

9/9/2024 7:58:48 AM

Ontario

I think for next year I'll do single layer, but I will definitely look at double layer later on because I'd like to grow watermelons, and they need a very hot year for use to have any success with it

9/9/2024 10:19:31 AM

valtierra/spain

In Spain, I decided to put a greenhouse in 2017, when I had 3 pumpkins that pointed to 2000 pounds, and a storm ruined my 3 plants, and the storms and the wind I have is very strong throughout the season. I have several days of very strong storms, and that's why I decided to set up a greenhouse. But in the greenhouse with high temperatures, it's real shit, if you apply some moisture to combat high temperatures, it will create many diseases. In temperate and cold climates the greenhouse is the best, but warm climates you have to be very careful. And you have to carry a very strict plan of fungicides, whether systematic or biological. Fans are very important, especially in greenhouses that do not have a top opening, you have to remove that warm and dry environment as it is. The plastic tries to buy it with protection from ultraviolet rays, and infrared rays, many fewer leaves will be burned.

9/9/2024 12:39:25 PM

Watlington, UK

1 - leave the plastic on. Roll up the sides and open the doors during the day, roll them down and close doors at night.
2 - yes get ventilation fan(s). Mine are solar powered, when the sun shines they vent out the hot air, when it's dark or cloudy they don't.
3 - disease is managable if you're on top of things. It might be harder, but not impossible, to remove and replace soil if you're under cover.
The benefits are immense - no more damage from hail, wind, thunderstorms or intense rain. No more animals chewing on your plant. You can control temperature and irrigation much better than outdoors.
One more thing - it can be a challenge to remove your pumpkin as it's indoors not outdoors, something to think about ;)

[Last edit: 09/09/24 5:04:07 PM]

9/9/2024 5:02:54 PM

Ontario

Hmm okay. That's definitely good to know. I never have problems with leaf scorch (our average temperatures rarely get much past 30° or like 90ish°, so we definitely won't have those same problems).
What's the thoughts if I take the plastic off the middle for july and august? Essentially making the greenhouse just an extra large early and late hoophouse? Since it's only about 30×50 feet of greenhouse it shouldn't be too hard to take off a single layer poly from the top. Would that negate the negative disease effects?

9/9/2024 5:04:40 PM

Ontario

Thanks gerald. I have thought about removing the pumpkin but I think that removing 1 hoop should be a like 30 minute job and that would give enough space to drive the trailer in the side if the plastic is off. Definitely rolling plastic during the day. I think I'll be able to vent nearly 10 feet of hieght the whole length of either side. Solar powered fans are smart, I'll definitely look into solar the next few years. I was already thinking solar would be handy for some stuff out there.

[Last edit: 09/09/24 5:08:33 PM]

9/9/2024 5:07:57 PM

Torrance, Ca.

Good move!

Count the top 20 biggest pumpkins this year and then see if they were grown in a greenhouse. I bet the number will be about 90% of them were grown in a greenhouse?

All great information above.

9/10/2024 10:43:38 AM

Ontario

Yeah I won't be in the top 20 each year still trying to break 1000 lol
But yeah, I figure the control it gives me should help a lot, and should be worth it

9/10/2024 5:36:14 PM

Watlington, UK

Put it this way, I'm no champion grower but my weights more than doubled when I went undercover; if you're able to it's a no brainer

[Last edit: 09/10/24 5:44:42 PM]

9/10/2024 5:44:17 PM

Ontario

Yeah I have heard that it can double. That's a huge part of why I'm doing it

9/10/2024 7:03:19 PM

Richmond, BC, Canada

Air movement is the most important thing for greenhouse growing. I have 14 fans in a 2000 sq ft greenhouse. Next year I'm adding a few more. Just adding fans is not the answer. It's the way the fans move the air that's important IMO. My fans are the oscillating type purchased at Home Depot for $20 each. They are mounted upside down and hung from the ceiling. The leaves of my plants are constantly in motion. The july 16th post on diaries show how some of the fans are mounted.

9/13/2024 8:22:08 AM