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Eveleth MN

I was building a pair of hoop houses the other day about 8'x4'x4' so I can get the seedlings in the ground May 1st. I was wondering if anyone had built a "climate control" setup and if it would be a good Idea or not. What I'm thinking of do is getting a small ceramic heater, using a small 120mm computer casefan, and a dual way thermostat to regulate the temprature in the hoop house. I'll set the ceramic heater to keep the air temprature above 45*f for the cold nights and make the small fan circulate in outside air when the temprature climbs above 80*f inside during the day (mostly since I have to work during the day and can't come home to open it up if its too warm out)

2/14/2004 12:36:12 PM

[email protected]

I found that 2 Patton Milkhouse heaters ($17 each at HomeDepot) almost got the job done down to Zero. At -5 we ran into trouble though.

A thermostat for wet climate use is the key to prevent overheating. Here is the one we're going to use:

http://www.grainger.com/Grainger/productdetail.jsp?xi=xi&ItemId=1611632371&ccitem=

This will run a shuttered fan (also from Grainger) that I think cost about $150 several years ago. This fan is overkill, but will get the job done.

Steve

2/14/2004 1:51:55 PM

Menomonie, WI ([email protected])

Rancherlee what several people do is make a smaller enclosure inside their hoophouse for this time of season you are refering to. A cheap styrofoam cooler or a rose cone and two 15 watt light bulbs to keep the plant warm at night. I say two light bulbs because one is a back up. The area the little pumpkin seedling takes is very small this time of season. Put it on before the sun goes down and take it of when the sun comes up...Your electricity bill will thank you.

2/14/2004 2:15:06 PM

Amherst, WI

What Shannon described above is what I do to protect the plants. I've had good luck with it. (Good idea with the backup bulb, Shannon.) I have a few photos of the setup in my '03 diary, check it out. I tried to heat the whole coldframe in the '02 season and found it was too big of a space to heat, some plants got frost damage that year.

2/15/2004 10:26:43 AM

I'm with Gordon... GO UTES!

It's a troublesome problem, as I usually leave for work
in the early morning, the absolute coldest time of the
24 hour period. Sure I can leave something over the plant,
but then it gets left there, and the plant stays in
darkness all the next day. Not a good thing. Sometimes my
wife can help, but... its a hassle for her. Then again, if
the light bulbs are on it...???

What I usually do is pound in three rebar stakes in a
triangle pattern around the seedling at planting. Then I
can easily drape a blanket around the seedling any night
when it may get cold.

As for lightbulbs and fans, be careful, one thing I
noticed in my first year last year is that it actually
rains inside the hoophouses! The condensation forms on the
top of the plastic and falls back down. I shattered a
couple of unprotected lightbulbs this way, as the cool
drop of "rain" hit the hot bulb and shattered it.

Regards, Cliff

2/16/2004 10:27:24 AM

Walton N.y.

i think your fan choice is a bit small to cool as that clear material can really heat up on warm days and would look into something bigger i don't remember the formula of how to figure out how much cubic feet per minute your fan needs to move but do remember that for proper cooling the volume of air inside the enclosed area should be changed every 1.5 seconds or overheating will occour -thats without shade cloth over the plastic

2/16/2004 10:49:15 AM

I'm with Gordon... GO UTES!

Just a tip for potential hoophousers out there... in my
12 foot hoophouse I found that daytime temperatures soared
about 30 degrees over outside temperatures. But at
night, the temps fall to about the same temperature as
outside. So if you're expected to be below 40, some sort of
covering or supplemental heating is required.

As long as there was lots of moisture in the houses the
plants never wilted in the daytime heat. And boy, did
they grow fast!

One nice thing about lamps is that you can put them on a
simple timer to come on at 23:00 and off again at 9:00 or
10:00...

Regards, Cliff

2/16/2004 3:04:10 PM

Eveleth MN

I'm wondering If can paint some 4" PVC pipe black and fill it with water to absorb the daytime heat/sunlight then help keep the heat up at night better.

2/16/2004 5:37:20 PM

[email protected]

I'm with Cliff on this one. Night heat is easier for me to manage with the help of my cheap little Milkhouse heaters. It was overheating that screwed me up so bad last spring. I'd head out in the morning & it would be 40 degress, cloudy, with the threat of windy storms looming. So I'd leave the hoops closed. By noon one day the sun had come out & the current temperature was 78 degrees. I came home to find wilted plants under plastic. The high temperature exceeded 105 seven time. It exceeded 108 twice. One of the 108's read 115 but I still doubt the accuracy of that thermometer on that day.

Anything I have to do this year to better manage temperature will happen. A 70 degree temperature shift in one day is much more than any decent plant should have to endure. AG's prefer a shift of 20 degrees or less.

Steve

2/16/2004 6:43:37 PM

Ontario, Canada.

Day time temperature can be controlled with gas charged automatic vent openers. Mounted on a hinge as the temps rise inside the hoop house the gas expands which extends a cylinder rod you attach to vent door. Bingo, you have daytime heat control. From Lee Valley at the link below. $49.50cad each. They are perfect for the working AGP grower.
http://www.leevalley.com/garden/page.asp?page=10543&category=2%2C43224&SID=&ccurrency=1
Controlling temperatures in a cold frame or greenhouse is straightforward with this automatic control.
It incorporates a gas-charged cylinder of adjustable volume. As the temperature rises, the gas expands; it will open a 15 lb window, more than adequate in cold frames and greenhouses. A simple adjustment lets you control the operating range. As temperatures fluctuate, the 12-1/2" long unit will open and close a window as necessary to prevent disasters.

2/16/2004 7:27:44 PM