Hoop House Issue...How to Solve Please!

I have read about lights and supplemental heating. But, I am trying to get only a few weeks either side of frost dates. If I were trying to go year-round, I would likely be in there at night camping out with a blowtorch...lol.

I just put the row cover on tonight, and hope that, with the jugs, is enough to help things along. I'll know for sure this week, as it's supposed to get down to 25 at least twice. This will be a good test to see if I can get enough heat during the day to warm up the water enough to get me through a night like that. Fingers crossed.

Thanks so much for sharing your story...and experience. Thanks to everyone so far. We'll see what happens in the morning....

I too was just after a few weeks "extra" but got stubborn and wanted to make it to Christmas. The lights were an easy fix. I am intrigued by the plastic bottles idea of slowly releasing the heat they collect by the day but not sure the gallons jugs are big enough.

http://www.flickr.com/photos/56292096@N03/5210221022/

http://www.flickr.com/photos/56292096@N03/5209625535/in/photostream/

These pics will give you an idea of how big the crop can get and how I covered them.

Where are you putting those jugs? I have a "work" space in between the two beds. Crawling under the plastic and tending to them in secret made me feel all child like again !! Let me know how the differential worked out pls . I might place a 30 gal black container instead of lights this time.

Temps are supposed to keep dropping during the day today. I will check the therm in a couple hours when we get back from some scheduled appointments.

I agree that the gallon jugs may not be big enough, but I have 17 of them in there and they are only in half of the 4x12 space....about 4x6 with about 6 open squares in the middle.

When I get home, I will take some pics to help me explain....thanks so much for sharing yours. I may be headed for Cmas lights myself....lol. And, yours look pretty classy being all white and not just junked in there.

It would be great if an engineering type could run the numbers to demonstrate if milk jugs have enough mass to be effective or if are they more likely garden lore. This is a simple case for math to support (or not) garden anecdotal experiences.

This may answer some of the engineering.

My air temps haven't been above 53 for 5 hours now. Since the hi/lo reset at noon, I don't know what the high was, but I know it was about 63 degrees outside the HH at midnight.

Here is the current set up. What you see are 2L bottles on the outside edge. Everywhere else are black painted gallon milk jugs. You will see the corner of one in the 2nd pic on the left edge of the image....




And, here is a shot of the thermometer inside while the air temps are 43F now outside. Looks like a good differential. And, looks like the water jugs hold fairly well.



I think we are on to something finally.

As for today, the temps are supposed to fall, and I won't be seeing any sunshine to combat the water jugs cooling off. I am anxious to see how the temps hold when it gets below freezing with no sunshine or warming help. So, tell me again, why don't we plant 6 weeks before frost dates again?

For me, the reason I use the hoops over the bed is to extend my season by several weeks on either side of the regular growing season. Cell division will occur to 36,F so I need to have a thermal mass that is going to keep the lowest temp between 34-36F. I have 8 water filled 1 gallon milk jugs painted black and this worked well in my 4X6, extending my 2010 fall harvest by about 4 weeks.

camprn wrote:For me, the reason I use the hoops over the bed is to extend my season by several weeks on either side of the regular growing season. Cell division will occur to 36,F so I need to have a thermal mass that is going to keep the lowest temp between 34-36F. I have 8 water filled 1 gallon milk jugs painted black and this worked well in my 4X6, extending my 2010 fall harvest by about 4 weeks.

Perfect. That is all I'm looking for, too.....for now. I know, like a boat, I will want more once I achieve my initial goals.

Hmmm... Christmas lights work whether the sun's shining or not! Thank you for the inspirational photos, staf!

No problem Miinva....glad to share. Hope to save others from too much pain of trial and error.

Nice job BBG. Glad to see it worked for you.

So of course, I'm totally going to try and use the idea now that someone else proves it works . Thinking out loud here.....I wonder what I might do on a cloudy day when the bottles don't warm well. Simply fill with warm water perhaps from the tap and place? As the crop grows though, I'm not sure that there will be room to place inside the squares. Tight fit but probably will be fine.

Great work again BBG.....awesome bird blog BTW

Staf, I have one even better for you.....hopefully providing non-scientific proof that the juggies work.

Last night got to 25F, and I only got down to 33F. I had no sunshine yesterday, and the air temps fell straight out of the gate from midnight to about 11am where they leveled off between 46 and 42 for the rest of the day.....again no sunshine and thick overcast. It hasn't been above freezing since midnight, today, and my low was 33F.

I think we underestimate just how long it takes water to both cool off and heat up. More details in a short blog entry. But, I'm suddenly jacked up about planting this weekend again. If I can safely get the mid 20's "covered" (pun intended), I have no idea how long that can extend my season. A month? 6 weeks? ....to be determined.

That's very encouraging news BBG. Don't underestimate how valuable and absolutely scientific your project is to the forum. Monitoring temperatures, thermal mass, trial and error, adjusting the project based upon the available data.....completely scientific in my book at least. I really thought the jugs would lose heat much faster..... Guess not....keep chuggin eh !!!

staf74 wrote:....keep chuggin eh !!!

Chugging.....Juggin....whatever works...you know the motto.

I plan to keep monitoring temps until I feel confident in my new "season." I know that will change from year to year. All I really want is to look at the weather forecast and say, "Hmmm...need the 2nd sheet of plastic tonight." Or, "Well, that's too cold for what I can do....looks like I'll be shuttin' her down for a couple months."

Just as long as I know what temps I can handle, the rest should take care of itself. And, I think that's all anybody really wants.....to reach the max of their desired efforts.

Not to bombard the thread, but since we have several spectators at the moment, here is my plan for the near future...

I will chart my temps by taking a reading 2x/day. In the morning to grab the low, and in the evening to grab the high. I will post like this...air/HH, and I will give you some clue as to the day's weather if it seems important to the temps. I will also note if I used both layers of plastic or if I vented the HH during the day. Otherwise, assume non-venting and the jugs and top cover won't change.

For example, today we've received about half sun/half clouds so far. This morning was 25/33. This afternoon, so far, is 37/74.

I am using a neighborhood weather station very close by from Wunderground.com, and my max/min therm inside the HH. I will likely only record in max's and min's for both, even though I am checking this much more often...due to my obsessive personality and something new to do until grass grows and I get to leave the house regularly again...lol.

LOL...37/74 is what the high ended up being for today. We had some decent sun, too. I was hoping to pop the 80's, but the air temps didn't provide much help this afternoon.

2nd layer of plastic is back on for tonight.

Another solid performance last night from the HH. Temps hit their lows at 1am and started climbing slightly after about 3am. I have 27/35. I am maintaining a solid 5-10 degrees above air temps the past couple days. I think I'll take it.

Last night had some freezing rain before daybreak, too.

Today is forecast to be sunny this morning, but cloudy this afternoon. Temps are supposed to get close to 50. We'll see.

Never got close to 50. Barely hit 42. The sun was never out....except for an hour or so early morning and the last 45 minutes of the day....basically, the worst sun angles possible. That said, the HH popped to 65 briefly, but is already back down to 50F.

We are currently hitting our daily high. We may continue to warm for another half hour, but that won't change the HH's high. So, call it....42/65.

Today...limited sunshine....27/35 lows.....42/65 highs. Tonight's low is supposed to be 38, so I am leaving the 2nd layer off. I expect the "HH low" to match it....maybe 39. Either way, no chance of freezing. If I had plants in there, I still wouldn't use the 2nd cover.

BBG,

Its been quite mild here in upstate SC. So much so that I've actually been wanting a frost to break out the plastic.....how crazy is that? Now I need the frost to test the thermal mass idea myself and can't get a break...go figure eh !!!!

I was wondering on your double layers of plastic. Are they touching or do you have something in between to create a dead air space? If they are touching, you might be surprised to see that the second layer might not be giving you any "R" value whatsoever. I found that out last fall too. Once they touch, they basically act as a single layer again.

Perhaps you might still get a decent differential with just the one layer...I'm gonna guess at 42/43 for you tonight seeing as I can't play.....Good game this....hehe

staf74 wrote:BBG,

Its been quite mild here in upstate SC. So much so that I've actually been wanting a frost to break out the plastic.....how crazy is that? Now I need the frost to test the thermal mass idea myself and can't get a break...go figure eh !!!!

I was wondering on your double layers of plastic. Are they touching or do you have something in between to create a dead air space? If they are touching, you might be surprised to see that the second layer might not be giving you any "R" value whatsoever. I found that out last fall too. Once they touch, they basically act as a single layer again.

Perhaps you might still get a decent differential with just the one layer...I'm gonna guess at 42/43 for you tonight seeing as I can't play.....Good game this....hehe

Staf, you hit the 1 degree differential right on the nose. And, that is what I expected, too....if not an exact match. 37/39 are my readings as of right now, but the 37 is because the temps are still dropping. As of 7am, our low air temp was 38. Despite the 8am air temp of 36.8, we seem to have bottomed and are back up over 37. That said, it is 44 inside the hoops right now. So, we do pick up some sunshine even through the thick overcast, which we should know by being on canoe trips on cloudy days as teenagers and still getting sunburned. Energy still gets in during daylight hours.

So, what we conclude this week so far is:
- Temps will pop under the plastic when we get sun....and pop fast.
- Temps inside hoops with one layer of 6mm plastic will run about 40* above air temps with intense sunshine.
- Temps will cool off super fast inside the hoops once sun angle is lost.
- With only one layer of 6mm plastic, night time temps will get within one degree of air temps....even with water jugs inside.
- The addition of a floating row cover makes all the difference....giving you 6-8 degrees of differential overnight. (My floating row cover is another layer of 6mm plastic draped over the milk jugs...sitting about 12 inches above the soil.

What we don't know, however, is if the row cover is trapping all the heat from the jugs or if it's the dual layer of plastic trapping the heat. I may move the milk jugs outside the hoops one night and cover them with the floating cover just to see if I still get 6-8 degrees difference. If so, I will wonder the effectiveness at all of hoops? I could just put the row covers on at night to retain the heat.....in fact, it would be easier.

As for the two layers touching, they don't. They are separated by about 3 feet, which also would have minimal effectiveness imo....too much space. If you look back towards the beginning of this thread, you will see the picture taken of the inside of the HH with both layers of plastic....the roof and the "floating row."

I would bet that the outer layer is still helping. It would keep the wind off the inner layer and reduce the heat transfer by creating some still air around the inner layer/jugs. I've noticed that my "hoop house/mini-greenhouse" was cooler on windy days/nights than in still air or when the wind was from the west (greenhouse on the east side, protected by my house).

My "greenhouse" fairly consistently ran at least 4-5 degrees above ambient temps at night, with my Christmas lights on, even when below freezing. When I took down my hoop house that was over the raised bed, I added those lights to the "greenhouse" and got more like a 7-10 degree difference or more (one of those strings had flasher bulbs on it, LOL). I would also get 20 or 30 degree daytime jumps, during warmer days, especially. I had to watch the expected highs like a miser watching gold prices.

My temp gauge that I could see from inside the house, failed about the time we got the really bad ice storm, but my plants faired well inside except the ones that dried out. It was too cold for me to even open the plastic, I would have frosted the plants checking on them. I had a high/low temp guage inside the greenhouse and the lowest it got during the ice storms (with 4 light strings) was 25 degrees, if I remember right. I'll take that over 14 degrees any day!

All in all, I would say a hoop house with Christmas lights, or other heat source, is a viable way to save tender perennials in pots and certainly gave me FAR more tomatoes than I would have had otherwise. I'm hoping to have a real greenhouse next year so I don't have to hassle with the plastic covered plant stands - very cumbersome to get into and close up. I won't even hesitate to repeat the hoop house over the raised beds to extend the fall tomatoes. In fact, I've set up each of my raised beds with a frame so I can make an "A" frame cover on them when the time and inclination leads me. I took apart the 3 hoop frame and reassembled into 3 separate single hoop frames with braces.

I gotta see pics now, duck. I think they would really help this thread, too.

My main issue with Cmas lights at the moment is: I don't have electric supplied to the backyard...just the front. So, I would have to really rig some extension cords to get back there.

And, you make a LOT of sense pointing out keeping the wind off and creating still space. Thanks for mentioning that.

BBG,

My mistake.....I thought both plastic layers were simply on top of each other covering the very top when you referred to two layers. One used as a floating row cover would make much more sense to the temps you are seeing and helps create that space. I should have looked more closely at your setup. I used two plastic layers together thinking at first it surely must help and got no real differential. I'm very impressed at your results and methodology. Very thorough

Now I just need that frost to try it out for myself..... can't win for losing sometimes with mother nature. Be careful what I wish for though eh ?

I used a 150 ft extension cord for my xmas lights with a 6 footer connecting all the lights to the main line but I wanna try this thermal mass idea ...

BackyardBirdGardner wrote:I gotta see pics now, duck. I think they would really help this thread, too.

My main issue with Cmas lights at the moment is: I don't have electric supplied to the backyard...just the front. So, I would have to really rig some extension cords to get back there.

And, you make a LOT of sense pointing out keeping the wind off and creating still space. Thanks for mentioning that.

I'm very bad about taking pics, then never getting around to posting them. I don't think I even have any pics of the triple hoop set up, but I can post pics of the 3 separate hoops easily enough once I get home. I can also take pics of the "greenhouse". I've been wanting to post pics of the arbor I made. I'm quite proud, free "junk" that was an arbor after about 10 minutes of welding (thanks DH!). Then we used the footboard of an old wrought iron bed that we got for $10 from the neighbor. Still haven't used the headboard as anything other than decorative leaning against the fence. The footboard has fence wire applied to it and is now the gate thanks to a little more welding and some bending. I'm home tomorrow, I'll see about posting pics.

Yes, staf, be careful what you wish for. I would gladly take down the hoops now that I think I have them tweaked appropriately for my needs.

And, very resrouceful, Duck. "Free" rarely goes wrong.

BTW, daytime highs were 38/49 with no sunshine and off and on rain showers. I am quite sure the single layer of plastic will lead to crazy peaks and valleys of temps. It's supposed to get cold tonight, but I didn't put the 2nd layer on because there are no plants in there, and we should know by now what the temps will do. However, when this weather breaks, and I get some sunshine, I will start playing with the covers again to see just how much heat it can hold on a day where the HH gets over 75F and gives the water a real chance to heat up more than a couple degrees.

Latest update is on the blog. But the jist of it is.....I forgot to put the 2nd layer of plastic on during the rain/snow last night and forgot to get outside early enough this morning to test the low. By time I got there, the max/min had reset for the day. I thought this happened around noon, but I figure I am wrong....again. LOL.

OK, I've taken pics, let's see if I can actually post them.


The arbor and view looking east with hoops in the background. Not the best view of the arbor, I'll try again tomorrow afternoon. You can see my worm tubes, compost heaps in the far background, salvaged rolling trash bins that I use to store manure or browns, whatever I have in excess while I'm waiting to build up more of whatever is lacking.
Before anybody asks, no that's not my barn - it belongs to the neighbor behind us.

The gate made from the old bed foot board.

A little closer on the hoops and below is the view looking north. The left half of the south most bed is asparagus - most of it just planted, some transferred from the north end of the right hand bed. The right half will be strawberries. I got some freebies, but they had been frosted and didn't survive.