Author Topic: Greenhouse film - would construction plastic sheet work?  (Read 3538 times)

funlul

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Greenhouse film - would construction plastic sheet work?
« on: February 18, 2016, 01:28:52 PM »
Hello all :D  I am trying to build a mini greenhouse for rooting the cuttings I recently received: figs, mulberry, and pomegranates. Well, the frame is done (4' x 3' x 2' from 3/4" pvc pipes plus 3-way elbows), but I am not sure if the plastic sheet I have on hand will work - not sure where they came from either, construction maybe?

My friend says it will burn the plants for sure because air will not circulate. I thought the idea of greenhouse is to lock in the humidity and maintain heat...? Ideas based on the photo? If it is not suitable, any recommendations for local selections? Many thanks!

Looking for scionwoods: loquat, cherimoya, jujube, chocolate perssimon

Bananaizme

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #1 on: February 18, 2016, 01:56:48 PM »
    This plastic should be fine . Just don't expect more than 1 season( if  even that ) because of the uv breakdown. But for what you're trying to do it should be fine . Keep a close watch on the temperature though. If you could build a way to vent off the excess heat that would be even better.

William

funlul

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #2 on: February 18, 2016, 02:24:17 PM »
I have two choices for the location, one is full sun between 2 trees, another is part shade, under my avocado tree. What would you recommend, specifically for rooting purposes?

    This plastic should be fine . Just don't expect more than 1 season( if  even that ) because of the uv breakdown. But for what you're trying to do it should be fine . Keep a close watch on the temperature though. If you could build a way to vent off the excess heat that would be even better.

Thank you William! There will be air vent for sure because the surface (mulch) is uneven. Hmmmm what is the max temperature allowed? Will put a cheap thermometer in there too, thanks for reminding.
Looking for scionwoods: loquat, cherimoya, jujube, chocolate perssimon

Bananaizme

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #3 on: February 18, 2016, 02:46:20 PM »
    As long as you can maintain 80-85 degrees in the dappled shade I would go that route . Are you going to be using bottom heat ?  Perhaps others could offer suggestions based on their experiences.

 William

HIfarm

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #4 on: February 18, 2016, 03:12:16 PM »
As you are describing it, it sounds like you are building a solar oven.  You need a top vent, assuming it is somehow going to vent from the bottom is not going to work.  These types of devices have been built for generations.  Look for designs on line for a cold frame -- that is basically what you are trying to build.  These generally have a top that opens & you can adjust the amount you open it to bleed off the excess heat.  If you are concerned about it drying out (a valid concern as the outside air coming in will have low humidity & will suck the humidity out of the soil inside) you may want to include some sort of water reservoir to minimize this.  You might also want to invest in a small piece of shade cloth unless you are confident that the shade is sufficient.

John

I have two choices for the location, one is full sun between 2 trees, another is part shade, under my avocado tree. What would you recommend, specifically for rooting purposes?



Thank you William! There will be air vent for sure because the surface (mulch) is uneven. Hmmmm what is the max temperature allowed? Will put a cheap thermometer in there too, thanks for reminding.

Pan Dulce

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #5 on: February 18, 2016, 03:19:45 PM »
I am currently using a very similar setup over two 20 x 60 Hydrofarm heat mats.  I leave three sides covered with the same type of plastic, down to the base and one side I open up as needed.  My setup is under an open air covered porch, and once my seeds and cuttings are rooted, I bring them out from under the plastic.  I use a Hydrofarm temp control for the mats, with the sensor a few inches into the soil of a 1 gallon container.  I have been getting close to a hundred percent germination/rooting over the last few months even with my outside temps dipping down into the upper 30's and low 40's.  I only have to water the pots once a week, and the plastic raises humidity up to 80 percent or so, and it stays there for days.  I use a cheap digital humidity/temp sensor.  Venting is minor in the winter, except to let in CO2.

If you want solid results with cuttings, build yourself an aeroponic cloner.  Lots of DIY videos on youtube and instructions on google. You just need to keep the water around 70 to 75 degrees F and the tub in full shade.  No plastic needed. You can build one in a five gallon bucket to do less than 10 cuttings or large tubs for bunches more.

FruitAddict

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #6 on: February 18, 2016, 04:18:30 PM »
If your plastic is the same quality than what I have (used for other purposes) and if your sun is just as hot as here in sunny South Africa, I can tell you, the plastic won't hold for long.  I also have a type of construction plastic and within two months it became brittle.  It is disintegrating at high speed.  You can't even touch it.

funlul

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #7 on: February 18, 2016, 04:37:20 PM »
Thank you all! As of now, I'd be happy if this can last one season. Trying to find the right combination of sunlight (outside heat) and air vent!

As you are describing it, it sounds like you are building a solar oven.  You need a top vent, assuming it is somehow going to vent from the bottom is not going to work.  These types of devices have been built for generations.  Look for designs on line for a cold frame -- that is basically what you are trying to build.  These generally have a top that opens & you can adjust the amount you open it to bleed off the excess heat.  If you are concerned about it drying out (a valid concern as the outside air coming in will have low humidity & will suck the humidity out of the soil inside) you may want to include some sort of water reservoir to minimize this.  You might also want to invest in a small piece of shade cloth unless you are confident that the shade is sufficient.

I assume heat oven will dry the cuttings even faster :o  SoCal is in full summer mode, hot and dry. So my priority is keeping them humid, not hot. Looking into cold frame, and under the shade it goes. Thank you!
« Last Edit: February 18, 2016, 04:47:24 PM by funlul »
Looking for scionwoods: loquat, cherimoya, jujube, chocolate perssimon

funlul

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #8 on: February 18, 2016, 05:43:41 PM »
Thank you all!

Here it is, sitting by my north facing wall, at a quite shaded spot with a thermometer inside. Still not sure how much sun is needed?




Looking for scionwoods: loquat, cherimoya, jujube, chocolate perssimon

stuartdaly88

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #9 on: February 19, 2016, 12:15:12 AM »
If your plastic is the same quality than what I have (used for other purposes) and if your sun is just as hot as here in sunny South Africa, I can tell you, the plastic won't hold for long.  I also have a type of construction plastic and within two months it became brittle.  It is disintegrating at high speed.  You can't even touch it.

I had the same issue in Gauteng.
Its even worse than just your greenhouse cover disintegrating as even three seasons later I was still picking little bits of plastic out of my soil :'(
Patience is bitter, but its fruit is sweet.
-Jean-Jacques Rousseau

funlul

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #10 on: February 19, 2016, 02:02:26 AM »
Today's temperature was H68 L49, and I believe thermometer hanging inside of "greenhouse" by the wall reported about the same temperature as outside. Humidity is pretty nice, though.
Looking for scionwoods: loquat, cherimoya, jujube, chocolate perssimon

Doglips

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #11 on: February 19, 2016, 06:29:53 AM »
For many (not all) plants, more sun the better.  The issue greenhouses have with the sun is the heat that it generates.  You can hit 120F easily in a greenhouse in full sun even in northern climes.  Shading means less sun which means less heat, but it also robs the plant of energy.  Then you start getting into alternate methods for cooling, such as ventilation, swamp coolers, misters, heat exchangers.
Manually ventilating is tricky, be vigilant if you go this way, the days get longer, the sun moves -  shading disappears.

funlul

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #12 on: February 19, 2016, 12:20:45 PM »
Do grafting and rooting like the same kind of environment? (temp? sun? humidity?)
I grafted two young loquats (1 gallon pot) this morning and put them in the mini greenhouse...


For many (not all) plants, more sun the better.  The issue greenhouses have with the sun is the heat that it generates.  You can hit 120F easily in a greenhouse in full sun even in northern climes.  Shading means less sun which means less heat, but it also robs the plant of energy.  Then you start getting into alternate methods for cooling, such as ventilation, swamp coolers, misters, heat exchangers.
Manually ventilating is tricky, be vigilant if you go this way, the days get longer, the sun moves -  shading disappears.

I moved the mini greenhouse (again) today from total shade into part shade with top vent.
Oh boy this is tricky! Will continue to monitor the temperature carefully. Humidity is fine.
Looking for scionwoods: loquat, cherimoya, jujube, chocolate perssimon

Doglips

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #13 on: February 19, 2016, 12:47:13 PM »
Do grafting and rooting like the same kind of environment? (temp? sun? humidity?)
I grafted two young loquats (1 gallon pot) this morning and put them in the mini greenhouse...

Grafting and root cuttings you want less than full normal light requirements.  You want time for the graft to heal or roots to form before the scion/cutting uses up all of its stored energy.

funlul

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Re: Greenhouse film - would construction plastic sheet work?
« Reply #14 on: February 23, 2016, 02:58:18 PM »
I built it bigger than originally expected, and still found myself nearly out of room...  ::) Moved young wax apple seedlings from indoor into "greenhouse". Also trying to grow few cherimoya / wax apple from seeds.

Temperature measures low 50s at night. Will see what happens at day when it gets warmer.
Looking for scionwoods: loquat, cherimoya, jujube, chocolate perssimon

 

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