Hoop House Issue...How to Solve Please!

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.

Okay so I gave it a try last night....was itching to. Weather channel had the forecast at 33 so thought i'd try the row cover idea with no thermal mass just to see what, if any, temp differential I could get.

As you see below, I surrounded the lettuce bed with some small border fencing I had lying around and covered with plastic (which was the folded layer from the other hoop setup so it was actually a few layers thick). Put the box in the middle to stop it from collapsing on the plants. Put the sensor from the thermom resting next to the lettuce and the actual thermom inside the hoop house on the gravel floor to get the coldest point. Then put the main plastic layer on and retired for the night.



Here's the thermom I'm using and the results....which are both good and bad.



This is a little worrying because I've learned I have a little micro climate going on from my nearest weather station and that 33 on the weather channel meant 31.7 for me last night. More worrying though is that the main layer of plastic seems to have given me almost no differential. BBG, similar to your results. It was a little windy so perhaps the real feel was 29 or so. So maybe it did give me almost 3 degrees but without the sensor placed OUTSIDE the hoop, I'm just guessing.

However, drum roll please for the results UNDER the floating row cover....



40.3 degrees.....An 8.6 differential....WOW. I'm astounded. Will try to not get too excited though. I won't be using that much plastic for the row cover for my regular setup as I borrowed the big plastic piece from the other beds that are not hooped as of yet and it was folded many times to fit. A single layer will probably drop that a bit but still....8.6 degrees is pretty darn good. I can't see the temps here getting below 25 again this spring. The ten day forecast has no frost and so I'm fairly confident that I can ride out the remaining few weeks WITHOUT supplemental lights / thermal mass etc. The plants are small enough in the early spring to fit snugly under the row cover. By the time the last frost passes, I won't need to cover them anyway and worry about them getting too big for the cover. In the fall, this won't work as they are soooo big by the time the FIRST frost arrives. I will go back to my christmas lights method again.

BBG, I'll keep posting results when I cover again but not likely for another week or so. Thanks for the inspiration...your efforts made me eager to try

Strawberries are in the 3 planters in between beds and go under the main plastic layer....or I just bring them inside for the night.

Hi!
I'm just new to the forum here...I, myself, have been conjuring up an idea to retain heat in some way. We live in Calif. at 3200 ft. and have cold nights and live in a holler! LOL So, my plan is (that is as soon as the two inches of snow that fell last night is melted!) to use old black vinyl hose and staple it on the inside of one of our raised beds and put them about two feet apart and run one across the top tying it to make a support. And then, being really a very thrifty and hopefully resourceful person, I am going to try a product other than the "floating row cover" Last year I happened to be in the local mattress factory and a huge roll of white stuff caught my eye. They use it as a dust cover stapled under box springs. So...........I smiled perty and he gave me enough to cover a bed! I'm thinking that it will keep more warmth in because the area that is covered will be less as it will be hooped across the bed itself.
LOL, I'll let you know...as soon as the snow melts and I can get out there!
Nancy

One thing of note, guys: I've always been taught, in life and meteorolgy classes, that wind chill has no affect on skin or plants...only exposed skin, like a dog's nose...or yours. (Yes, I actually majored in weather, but wasn't ever any good with hydrodynamics classes.)
Odd duck, your stuff looks awesome. You have all your stuff organized and in it's place. You have several large beds, and you can immediately tell how much space SFG saves us. And, in a separate discussion someday, I'll have to pick your brain about the worms and whatnot...as I haven't made it that far into gardening techniques. Awesome, thanks for the pics.
Staf, I am not surprised. When I figured out you were talking about 31.7 being the air temp OUTSIDE the protection, I knew you would be at least 33 inside. I love the 40, though! You likely trapped heat close to the ground with the low cover and all the moisture in the soil and the plants "exhaling" probably created enough thermal mass in that small space to really keep your temps up. I think that's the secret, and why I want to try measuring things without the hoops in another area of my garden soon. I am not convinced the 2 layers helps because there is so much space between the layers in my setup. I do agree it helps keep some wind off, and that part does affect things a little, but not 9 degrees of differential.....THAT is trapping that heat so close to the ground....has to be.
I also have a microclimate; we all do. I bought another therm just because I can't stand looking at a weather station a mile away and not knowing if it's in shade, under a deck, in the sun, etc, since it's a "personal weather station" on the Wunderground network. So, I have my own set up....it's just not a max/min, which i will rectify around Father's Day when I get my real Wx station and set it up....can't wait. My therm currently runs a degree higher than the station I watch, and it does so very consistently.
Thanks, you guys, for participating, too. Because of you, I have not only learned a lot, but we've learned faster. Nothing like bouncing ideas, and trying a couple of things together to confirm and deny concepts. I just hope others get something out of this, and learn how to set up their hoops to max that heat retention even if they aren't participating vocally.
For a bunch of "non-scientists," I think we are starting to figure this thing out.
As for my results, the past two days were....33/34 thursday, 31/35 friday morning and 34/46 friday afternoon, 32/35 last night. Notice the differential in the high? That is completely overcast; we haven't seen the sun in three days here. But, it is still enough during the daylight hours to pop the hoops 10 degrees through the clouds. That is why the first layer is still important..
..it just helps at night to have that first layer as close to the ground as possible, imo. You may add cloches or a 2nd row for added protection, but we are starting to see that just putting that single layer of plastic about a foot from the ground really traps heat at night. Yes, I know Staf folded his stuff over, but we know you get no insulative protection from the places the plastic touches, so Staf likely had pockets of protection and pockets of single layer protection randomly covering the plants.

Wow, this is fun!

Nancy....err, VeggieO's, please do let me/us know. That is a great sounding material. My dog used to rip that stuff up from underneath the bed when he climbed underneath, if it's the same stuff. Smiling pretty gets me everytime, too.

So I must take more time with my posts. I think I'm getting my point across as I type fast until I go back and read it later on and sometimes think...DUH.... You are not making sense...

I don't know at this point if I even need to clarify because I don't even understand my own post LOL but 31.7 was the temp outside the ROW cover but inside the second plastic layer that went over the hoops. I was not sure of the outside air temp but probably about the same. The forecast last night was for 33 but clearly it dropped slightly lower than that in my backyard, assuming of course that my digital thermom reads correct.

Interesting point you make that the main layer might not have that much of a help to insulation and the logic that it needs to be closer to the bed to really get that differential. A smaller space to retain heat makes perfect sense in that regard. Under the row cover was relatively "toasty" at 40.3. I might experiment too with just row covers the next time low 30's are forecast. Even being rasied on gravel, the bed must still be trapping some of the Earths ambient heat to give me almost 9 extra degrees. Blows my theory that SFGing might NOT lend itself as well to Eliot Colemans heat trapping row cover methodology due to the raised sides. Great news.

Wind chill not affecting plants....Good knowledge BBG . Never knew that. Makes me worry a lot less now.

Odd Duck, love the set-up. I hope this does not sound too dumb but are those kinda little white towers around your garden some kind of watering device? I see the hoses look connected but could not quite work it out? Also, love the frames to support trellised plants. They look custom built. Did you weld them? IMPRESSIVE.

VeggieO's....would love to see you chime in once you get set-up. Seems like you would have some great info to share with those wild temp swings down in the "holler"....Welcome aboard

I gotcha now, Staf. Yeah, I assumed that was straight outdoor temps at 31F. I haven't had anything below 32 inside my single layer yet. But, I had the double row on, and only one therm, when things got into the 20s. I'm sure with only the one layer, things were below freezing on those couple of nights.

Yesterdays lows...32/35 with a single layer. Highs...42/49 with no sunshine yet again. This mornings lows...36/39 with a single layer.

I am trying like crazy to let every ounce of the sun's daytime energy inside the HH and into my water jugs. Without sunshine, I'm sure they don't vary much more than a degree or two during the day. I would like to see them get a LOT warmer to help more at night.....but I needz sunz shining for that to happen....lol.

This week, there are a couple of days (Monday, for sure) that we are forecast to have a hard freeze....mid to low 20's, I think. Hopefully, I get some sunshine on the HH before that or I may be doomed. The jugs have likely cooled down close to the HH and air temps without the sunshine to warm back up a bit. Those nighttime lows will certainly get the 2nd cover pulled out again. But, these nights are getting rarer by the day. So, after Monday, if there's no chance of mid-20s in the 7day forecast, I will try and Tplant my broccoli and cauliflower.....and wait and see.

25 is the forecast low tonight......2nd layer is now on for tonight. Will let you know in the morning, but I don't think I'll have much of a problem with freezing temps for long. And, I've survived 25 this way before (poet and don't know it...lol).

Today was sunny....really sunny....for the first time in several days. Air temps hit 47.....HH hit 92 before I opened it at 10am. Since it was so cool today, and I wanted the heat to refresh the jugs, I only opened the first spring clip (where you usually see two) to allow the ends to open only slightly.....just a hole instead of completely open. I also did this to keep the rascals out that destroyed my seedlings yesterday. (There will be more on that in my blog soon.)

Air temps leveled out with no heat retention after a couple hours being left open this way and hovered at about 5* over air temps.

The official numbers for today are 47/92.

Ok.... here is my setup, a bit smaller scale than BYBG's but same basic principles I think.






Hoops right over my table top, than inside a layer of the agribond fabric over wire hangers. For now I plan on a little lettuce and spinach, just to get me started a few weeks earlier with the spring greens.

If all goes well with this, I will try to do a similar setup over one of my tomato beds to try to get those in a few weeks early as well, about 3-4 weeks before my frost date.

Last night outside temps dipped below freezing (31 low) and inside my HH showed the lowest temp was 36. I can live with that, and hopefully my greens can too. I will put in another bottle or two (if I can squeeze it in there) and I guess if temps get rediculously low I will throw on a blanket at night.

It's only seeds... if i kill everything, than I can just replant

Thanks for the pic there....gives me lots to think about. So...the water jugs absorb the daytime temp and then stay relatively warm at night helping to keep the temp up. Nice! It sounds a lot like our temps lately...20s at night but should be warming up a bit. In the mountains here, it can change so quickly so one has to be prepared for the cold if it should come.

It's my understanding that painting the bottles black will absorb the sun even better, however I didn't have the paint and didn't feel like spending the money. Probably only a few bucks and might do it later, just didn't want to spend the additional money for the gas for a special trip to get it.

I don't know how well my setup will work if it gets down in the low 20s or lower, but hopefully I won't have to find out.

Jen, yours looks great. The only thing I would add is another bottle on the opposite sides to cover your freeze down into the upper 20's. That 5* differential should hold fairly consistently, but more water is like "more cowbell;" it just makes you feel better.

As for painting black, it does help imo. And, a can of spray paint is about $2 if you buy the Walmart cheap stuff......it's about a pack of seeds if you think of it that way.

To those that haven't set up their hoops yet, I would say that your main concern is retaining heat, as you've read. However, a major way of accomplishing this is to remove the 2nd layer of plastic during the sunshine and push the envelope before opening the 1st layer. You want it to get a little hot inside. And, you want as much sun to hit the bottles as possible. I have even thought of pulling the bottles out of the HH and putting them in completely unobstructed sunshine. However, I haven't "tested" this yet. The competition would be between indoor temps in the 80s vs outdoor temps in the 50s.....does direct sunshine overcome the ambient temps inside the HH? That would be a question to solve. And, should be easy with a meat therm and one bottle inside and one outside. But, I digress. For now, I would recommend at least taking away the 2nd layer of plastic to let more intense sun hit your bottles during the day.

Last night, I went below freezing...26/31. Part of the reason was I didn't use as many bottles under my 2nd layer. Another is I didn't use black bottles...there were a couple new unpainted ones because I didn't feel like moving things around. And, I did open the hoops yesterday aftenoon to let out the 92F air inside. Had I kept it in, I imagine my bottles would have been warmer through the night, and kept me at or above 32. Either way, 31 was only touched for a couple of hours at most....nothing that kills lettuce, spinach, and/or peas. Tomatoes and whatnot won't go in until my risk of going below 25F is very minimal.

staf74 wrote:

Odd Duck, love the set-up. I hope this does not sound too dumb but are those kinda little white towers around your garden some kind of watering device? I see the hoses look connected but could not quite work it out? Also, love the frames to support trellised plants. They look custom built. Did you weld them? IMPRESSIVE.

The white tubes with the inverted plastic pots are the worm tubes, pretty much as Josh described in his thread. They are not connected to the watering system, the hose just happens to lay next to them. The hoses are just hooked to sprinklers. I haven't yet set up a proper drip watering system, that's on my list, though!

The frames are just bent 1/2" electrical conduit. They are connected at the top to the long piece with end to end connectors. The side pieces are drilled at the meeting point, then connected with bolts, split-type lock washers, and nuts. The galvanizing makes welding conduit a bugger, so we had to use alternate options.

I don't know what kind of pain would be safe to use. I garden organically so I'm hesitant to put anything... unnatural... on my soil.

jerzyjen wrote:It's my understanding that painting the bottles black will absorb the sun even better, however I didn't have the paint and didn't feel like spending the money. Probably only a few bucks and might do it later, just didn't want to spend the additional money for the gas for a special trip to get it.

I don't know how well my setup will work if it gets down in the low 20s or lower, but hopefully I won't have to find out.

I did my little side-experiment for you today. I put one black jug in the sun, left one in the HH, and left a clear one in the HH, too. I didn't put a clear one out in the sun, though. But, after only one day, the results were pretty clear.

Our air temps got up to 58F today. The clear jug only got to 63F. The black jug out in the sun got to 62F. And, the black jug in the HH got to 67F! Clearly black is better. But, only using a clear one is better than putting a painted one out in the sun....but not by much.

As for the day, I got to 58/83F today. I only partially opened the HH, though, and the sun was out ALL day for a change. Once the sun angle was lost, the HH came back down to air temps really quick, as I was outside with the kids while it happened. I mean within 20 minutes the HH went from 70-ish to 55F. I don't know when the 83 happened because every time I checked (about 6 different times), my thermometer showed low 70s at best.

I put the 2nd layer on tonight since we are supposed to drop to 31F. I don't want to take the chance with my new transplants of a night the weathermen miss by 2 degrees. However, I used the 3.5mm plastic instead of the 6mm. I folded it over 4 times, not on purpose, but I actually think it will be a great thing because it will have air pockets all in the folded up plastic (when I say folded, I don't mean neatly folded like bed sheets). That insulation will be interesting to see tomorrow. I bet I don't get down to 40F inside the hoops with that plastic combining with the heating from the day.

Have a good night, all. I'll report in the morning.

I used to use a camp shower bag that was designed to heat the water by laying the water filled bag in the sun, so your shower water was passively warmed. This plastic bag had a clear side and a black side and the idea was to lay the bag clear side UP. The idea was the heat energy went into/through the water even before getting to the black part, which absorbed even more heat to transfer to the water.

Maybe you can try painting just one side of a jug, setting it so the paint is on the north side so the light/heat goes into the jug then hits the black side and gives up it's last bit of heat energy. Do you have one more jug and a bit more paint to experiment with?

Do I have more than one jug to dedicate to the experiment? Don't make me laugh....

(Not that you know this but...) I have three small children guzzling milk like a baby whale. I produce two milk jugs per week. In a year, I could likely climb up the STL Arch on my milk jugs.

OK...just joking around with you. I know you didn't know all that.

But, yes, I can put one out and paint just the back and re-run the experiment. For some people, it would be hard to accumulate as many milk jugs as I have in such a short period of time. But, Sunny D, orange juice, 2 Liter bottles of soda, etc, all work, too.

However, I cut the bottoms off my 2 Liters now and use the top as a potential cloche and the bottom as a vermiculite starting tray......




Last night was 33/37. Not quite the differential I was hoping for, but certainly safe enough.

My laughing in my post was because pretty much every one can come up with another milk jug, but even more so on whether you would want to run yet another experiment. I knew you would, I just thought it funny that now we're suggesting experiments to order!

I added two more bottles yesterday and we had a really sunny afternoon. Last night I went out and put a blanket on top (since my HH is so small one blanket was sufficient). The low outside was 27, inside the HH the lowest was 40. That works for me! I vented this morning, but I just hope that I don't have the opposite problem and it gets way too hot today while I'm at work.

I have 6 baby lettuces and I planted 6 spinach seeds, I worry about the lettuce getting fried if it gets too hot.

Odd Duck, I find that funny, too. It would be fun to get paid to do scientific experiments. Oh wait, people do. Hmmm, maybe I chose the wrong major in college.

Jen (for some reason I had a Coyote Ugly flashback and wanted to just call you Jerzey), that is a great differential. Now, you don't have to worry until temps go into the low 20s on sunny days. Once you know what it does on cloudy days, you can adjust your frost date to match....likely with confidence. You may acheive Miami status before I do...lol.

I figured I would just copy/paste the quick update I put in the blog today since I would say the same thing here....


Just a quick update. Not a lot has changed, but…

Hoops still hold well at 4-5F above outside air temps. I haven’t used the 2nd cover in awhile, and still haven’t dropped below freezing. Last night was 34/38F.

The veggies inside seem ok. The broccoli and cauliflower seem to be thriving. The lettuces are experiencing some apparent shock; however, I have other transplants ready to take their places if need be. No peas have sprouted, nor carrots from the direct planting I did 10 days ago….but that is to be expected (and I dont know the extent of the digging damage I took from a squirrel…or my dog.) I do have a spinach plant poking up from the direct seeding, so that’s exciting.

I will be transplanting carrots and more spinach this afternoon. These sprouted from the vermiculite cups method I used a week ago. And, the others from this attempt are already in the garden. More on that below.

I planted a tray of lettuces yesterday in hopes of transplanting them next weekend.

The method I am using is pretty simple. I was impressed enough with the vermiculite, I bought some brownie trays. I poked holes in the bottoms, and laid some paper towels over the holes. I filled them with an inch or so of vermiculite and watered it down. Then, in rows marked by popsicle sticks, I planted 5-8 seeds of each lettuce variety. I sprinkled dry vermiculite over the top and set aside for a few days. I should see something in a few days. When their baby leaves open fully, I will pull them out of the vermiculite and pop them directly into the garden.

Pics coming soon.

Quick update......another frost last night.

7am this morning.

Outside Air Temperature - 28.8
Under the first plastic cover - 33.4
Under the floating row cover - 38.7

Nice differential. No thermal mass used. Was hoping to use the plastic bottles but simply not needed. Potential for another light frost Thursday night.

Then snipped about 20 big juicy spinach leaves for a snack today and set off for work.