PVC cages for cold protection

[kengland]

I plan to build out a number of PVC cages to help shelter my trees this coming week. I have a number of flowering and young trees including bananas (around 40). The frames will be about 1 to 1.5ft taller and wider than each tree.

With that said, I'm going to use 1.5MM plastic. I know the rules, can't touch the foliage, ventilation, excess heat etc. I know it's verboten and ag cloth is the preferred choice. I plan to vent the top, keep it off the tree, and take it off each morning.

Anyone else gone this route?

[Kevin Jones]

Sounds like what you are doing is fine. When the weather moderates you can just remove the cages until you need them again. I do essentially the same thing except I call them Greenhouses.
Walk-in cloches really. Tinker Toy pressure treated 4X constructed frames covered in UV resistant greenhouse plastic. Ventilation... Open or close the doors depending on the weather. Space heaters for the really cold nights - 32 degrees or less.

Kevin

[BP]

Sounds like what I planned to do but instead I decided to push it and see how the plants not in greenhouses do as we have had a warm winter so far, just dipped below freezing last night for the first time. Post pics when you do it? Sounds sweet and its always helpful for me to see other ideas. 1.5mil seems a little light possibly, just for tearing and such. Currently I just have heavy row covers draped over everything from a line above a-frame style; it is not the best set up.

[Kevin Jones]

I'm using 6 Mil Clear Greenhouse Plastic Sheeting.
Cost a little more but lasts several years and is pretty durable.
I order it in oversized dimensions and custom trim to fit.

Kevin

[kengland]

Thanks All,

I'll post a pick or two of the frames in a bit. I chose 1.5mil not 100% sure plastic would work. It's a nice compromise. I'm hoping for a 4-6 degree difference. It's supposed to hit 32 for a low where I'm at on Tues. It's usually for just an hour but that's enough to decimate flowers. Not sure what I'm going to do with my bananas. One of the plants has a flower that just came up three days ago. It's not unpacked yet but wow what a bummer if it can't be saved

[kengland]

I am going to swap out the 1.5mm for 4mm. Take a little risk but given what's at stake, I think it will be worth it. I have a few more to go, but this is the gist of what I'm doing

[Kevin Jones]

How will you attach the plastic sheeting to the PVC?

Kevin

[kengland]

I'll be wrapping the cages with the plastic and then "clipping" the plastic to the cage using these...

[xesoteryc]

I'll be wrapping the cages with the plastic and then "clipping" the plastic to the cage using these...

Lowes has 12in stakes by Grip-Rite that are 98cents that might help secure your setup as well

[BP]

I am going to swap out the 1.5mm for 4mm. Take a little risk but given what's at stake, I think it will be worth it. I have a few more to go, but this is the gist of what I'm doing

Those look pretty nice! I'm going to get those clips

[Kevin Jones]

You might want to anchor the cage or they could go tumbling away.

Kevin

[Kent01]

Few things to consider
1. It may be better to have a conical shape to capture more heat from earth.
2. Adding wood chips and watering them will provide heat.
3. Frost clothes can provide better insulation compared to plastic sheet 

[bovine421]

I am going to swap out the 1.5mm for 4mm. Take a little risk but given what's at stake, I think it will be worth it. I have a few more to go, but this is the gist of what I'm doing

That'll come in handy for Midsummer grafting. Throw some shade cloth over it

[shot]

The wind load on those,yikes!Rebar stakes but those big cages could flex hard.There are two kinds of freezes ,advective freeze 30mph winds and radiative freezes close to calm wind.Small sprinklers inside cages would provide adequate heat.Maybe guide wires at top corners anchored on those big cages

[fliptop]

I posted before about what I do that I think is somewhat similar? I got a bunch of 6' bamboo stakes from AM Leonard and I surround the tree I want to protect with either three or four bamboo stakes:



I then use clothespins to clamp the frost cloth to the stakes:



These held up surprisingly well to wind (didn't lose any coverage as a result of wind and wind gusts). I had built frames years ago out of wood (similar to those PVC ones) and they got knocked over in the wind. I think being driven into the ground and having some flexibility helps with regard to the bamboo.

[kengland]

The wind load on those,yikes!Rebar stakes but those big cages could flex hard.There are two kinds of freezes ,advective freeze 30mph winds and radiative freezes close to calm wind.Small sprinklers inside cages would provide adequate heat.Maybe guide wires at top corners anchored on those big cages

Anchored down using 12" ubolts. Three for each horizontal. The angle is east/west as well. Winds here typically blow in that direction. The one large cage protecting the star fruit has inside stakes that are tied to the structure. We'll get no where near 30mph winds where I am. Expecting a gust or two to 15mph

[kengland]

I posted before about what I do that I think is somewhat similar? I got a bunch of 6' bamboo stakes from AM Leonard and I surround the tree I want to protect with either three or four bamboo stakes:



I then use clothespins to clamp the frost cloth to the stakes:



These held up surprisingly well to wind (didn't lose any coverage as a result of wind and wind gusts). I had built frames years ago out of wood (similar to those PVC ones) and they got knocked over in the wind. I think being driven into the ground and having some flexibility helps with regard to the bamboo.

Very nice. What were the conditions when you set this up...wind mph, temps, etc?

[fliptop]

I believe we were forecast to go down to 34 °F but it didn't get that cold. I don't remember the windspeed nor gusts, but it was enough to keep me cursing throughout the whole process. And I have to say, I was impressed with how effective a hold clothespins on frost cloth had.

I'm now seeing some forecasts here for 35° tomorrow night (local news even said there's a possibility of frost) and I only plan on covering stuff that was newly planted. I'm not expecting anything that doesn't get covered to die, but am guessing I'll lose some or all current blooms if it does get that low. C'est la vie.

[shot]

This cold spell is really nothing.I'm thinking of how bad i have seen it get in Florida past like 1989 were it was 18 to to low 20s in south Florida and winds that were 30 to 40 mph it was catastrophic freeze event.

[brad]

Please share your data, but in my testing this sort of greenhouse makes it colder inside than outside.  The data here is blue=outside temp, orange=inside greenhouse temp.  The greenhouse is a tent style extremely similar to your design.  The reason is that it gets very humid, so during the night there is an increased evaporative cooling effect inside which drops the temp lower than outside in open air.

I have since modified my design to have more air vents and two 5 gallon buckets of electrically heated water which does keep it warmer inside, but not by enough to warrant the complexity, so I removed the electrical and left the vents which keeps it identical to outside temps with a slight bonus of no frost forming directly on the plants.

The increased daytime temps can also be a problem which can prevent hardening off and mimick a false spring, but I'm pushing along to see how actually looks after 1 full season.

[kengland]

Brad, that's fantastic information. I have a weather station near the center of my hobby orchard and was planning on placing a humidity/temp reader on a platform inside a structure to validate the effort. I am using 12f wide sections of 4mm. I plan to vent the top of each structure but not sure yet how. I thought about cutting 1/2 holes (two or three per side), creating a seam somewhere, etc. Still not sure. I'll report back.

It's forecasted to hit 32 for an hour here. Just enough to do some damage. I'm sure all will be fine but I'm going to fight mother nature even if it means $12 per avocado/mango!

[BP]

I was going to say something similar. Its really easy to raise the highs with my cheap plastic greenhouse setup but my thermometer says my lows can be a couple degrees lower overnight when the sun goes down, but not always. The plants are still trying to actively grow because of the warmer highs. The condensation, drips and lack of air flow is a problem (which goes away if I leave the door open)

The other setup I have with a frost cloth aframe draped around the plant to the ground mightt raise the temp a bit but I'm not sure of that. It definitely freezes on the outside, keeping the leaves free of the frost so far

[brad]

best of luck, I'd love to learn new methods for keeping my plants alive as well.  Not a paid endorsement or anything, but for reference these are the temperature monitoring probes I happened to purchase for this test: https://a.co/d/2n848v0

I also used a 500 watt aquarium water heater to heat the 5 gallon bucket: https://a.co/d/45W1cWM

this showed around a 3% increase in temps, so not worth the cost of electricity for me, but it does also keep the soil very warm, so I had an idea to make a water bladder in the shape of a donut around the tree on the ground then stick the heat probe in that.  If anyone wants to take that idea, let me know how it goes

[greenerpasteur]

I dug this mango 3 months ago. I'm going through all these troubles so it can be healthy strong for grafting season.

I build a cold frame greenhouse with 1/2" insulation and greenhouse plastic on the outside. 1" thick insulation was too thick to bend into a circle but would have been more efficient.

 I used roof deicing cable for the roof and incandescent Christmas light. It's maintaining air and roots 65-70F for around $0.25/night. P

[BP]

^^^ incredible work, I'm impressed

I forgot to add that the cheap greenhouse setup was colder than outside as I approached freezing a few nights ago, and then it stopped dropping and stayed at 33f while outside dropped to 29 overnight, which was interesting to me. I didnt stay below freezing during the day which probably helped