Hoophouse heating question

Nightshade · January 22, 2009

I almost have my hub talked into building a cattlepanel hoophouse on a cement pad that is already in place here. I'd like to use it for growing tomatoes after their final potting up, changing out the plastic to shadecloth later in the season.

In the meantime, I'm trying to figure out how to balance benefits of the shelter with cost of heating it. Our nighttime averages from January through May run something like this: 39/40/41/44/50F. If the minimum standard temperature needed for tomatoes to set fruit is 50, do I need to maintain that for the entire night, or could the temperature be allowed to dip below that for a couple of hours?

Thanks,
Jan

Wi-sunflower · January 22, 2009

First off because you aren't actually talking about below freezing temps, you could probably get away with not even heating it.

Temps in a greenhouse will usually run about 10 degrees above outside. The cement pad will soak up quite a bit of heat on sunny days.

Something I've done for years is to use water. If you can scrounge up some old cattle tanks, use them for your "benches" or in the back of the greenhouse. Even if they have holes in them, you can line them with 2 layers of 4 mil plastic and they will work fine. Put some boards or snow fence on top and you have a table.

Depending on size you will need several tanks. If you can get somewhere in the 2-3 gallons / sq ft of floor space, you will be doing quite well.

Don't forget that while the plants are small you won't need to worry about the temp for flowering, so you just need to keep them from freezing.

Doing a second covering of the plants at nite inside the greenhouse can also help if the temps look like they are going to be quite low. Here is a page that shows a simple method using PVC pipe. http://knapps-fresh-vegies.netfirms.com/greenhouse.html
I've used something similar out in the field too to get a bit of a jump on the season.

Good luck with your greenhouse / cold frame, what ever.

Nightshade · January 22, 2009

Thank you, my friend. You're the best!

That's all good news. i'm sure i can meet your recommended gallons/sq. ft.

j.

Wi-sunflower · January 22, 2009

For anyone in a colder area that actually does need to heat the greenhouse, using water and a small household water heater works well. I put a pump in one of the tanks. Connect with garden hose to the water heater and more hose thru the tanks. Be sure to end the hose back in the same tank as the pump. Usually about 100 ft of hose in each tank will get the water up to 80* - 100*. Putting your seedling flats on top works as a good germination area.

January 22, 2009	#1
Nightshade Tomatovillian™ Join Date: Oct 2008 Location: So. California Posts: 178	Hoophouse heating question I almost have my hub talked into building a cattlepanel hoophouse on a cement pad that is already in place here. I'd like to use it for growing tomatoes after their final potting up, changing out the plastic to shadecloth later in the season. In the meantime, I'm trying to figure out how to balance benefits of the shelter with cost of heating it. Our nighttime averages from January through May run something like this: 39/40/41/44/50F. If the minimum standard temperature needed for tomatoes to set fruit is 50, do I need to maintain that for the entire night, or could the temperature be allowed to dip below that for a couple of hours? Thanks, Jan Last edited by Nightshade; January 22, 2009 at 05:00 PM.

January 22, 2009	#2
Wi-sunflower Tomatovillian™ Join Date: Nov 2008 Location: Wisconsin Posts: 2,591	First off because you aren't actually talking about below freezing temps, you could probably get away with not even heating it. Temps in a greenhouse will usually run about 10 degrees above outside. The cement pad will soak up quite a bit of heat on sunny days. Something I've done for years is to use water. If you can scrounge up some old cattle tanks, use them for your "benches" or in the back of the greenhouse. Even if they have holes in them, you can line them with 2 layers of 4 mil plastic and they will work fine. Put some boards or snow fence on top and you have a table. Depending on size you will need several tanks. If you can get somewhere in the 2-3 gallons / sq ft of floor space, you will be doing quite well. Don't forget that while the plants are small you won't need to worry about the temp for flowering, so you just need to keep them from freezing. Doing a second covering of the plants at nite inside the greenhouse can also help if the temps look like they are going to be quite low. Here is a page that shows a simple method using PVC pipe. http://knapps-fresh-vegies.netfirms.com/greenhouse.html I've used something similar out in the field too to get a bit of a jump on the season. Good luck with your greenhouse / cold frame, what ever.