Greenhouse with automatic passive rain watering

[Christophe]

I present to you my greenhouse with automatic rainwater irrigation which has been working well since 2019.

It's a very simple idea but it's very effective ... when it rains ...

The idea is to put a gutter supplied with rainwater with a slight slope and to drill it regularly at the height of the water level (to be done at the first filling). Thus the holes are not at the same height in the length of the gutter and the water flows (more or less) regularly throughout the greenhouse.

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I could have made it simpler with a horizontal gutter and holes at the same height, see an overflow system, but that would have made the annual cleaning a little more difficult and the PVC gutter tends to deform (hot, cold ...), so a slope is better ...

If your greenhouse is larger, you can use several gutters.

In the photos there is no water because I had just done the annual cleaning.

Roof section used (1/2):

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Collector on the vertical gutter:

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Arrived in the greenhouse:

Feeding the gutter: at the beginning I used a buffer tank and the gutter was fed by the overflow, but hydraulically in my config it was not terrible, the tank had difficulty in overflowing (not enough height with the collector rainwater) so ultimately a live feed works better!

A buffer tank is obviously interesting during the dry season!

Examples of holes:

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Outlet (removable for cleaning or frost protection, no need to do so ...):

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Here you are!

The only condition is to have a large section of the roof nearby to have good irrigation of the greenhouse, although it is quite possible to use the roof of the greenhouse to collect and have the hygrometric equivalent for the same surface " without greenhouse "...

But given the forcing of a greenhouse, it is better to collect on a larger section. Obviously, it is also necessary that the greenhouse is "below the pan" at home it is limited (less than 1m) but it works well in direct supply.

If you have quite a bit of height between the collector and the greenhouse, you can also use porous irrigation pipes. Does not work directly at home: depending on the pipe I think it takes 0.2 to 0.3 bars ...

[Milien61]

Hello,

Christophe, do you have any feedback on your passive rainwater irrigation system.

I want to make a somewhat equivalent system by collecting rainwater falling on the greenhouse (6,5 x 18m) and directing it immediately to the ground of the greenhouse (as if it were actually raining through the tarpaulin) . The goal is to give the soil a sufficient water reserve to get off to a good start at the start of summer and delay the first waterings of the plants as much as possible, knowing that I am strawing to limit evaporation.

The system I'm considering is slightly different:
- two gutters on either side of my tunnel greenhouse, each with a downspout,
- we pass under the tarpaulin and we supply two perforated PVC pipes placed more towards the center of the greenhouse (because the ground on the edges still benefits from the rain by oblique diffusion of the water),
- the two perforated pipes are placed on flat tiles along the length of the greenhouse with holes adjusted as necessary so that the water is distributed over the entire length.

And if I see in mid/late summer/early fall that the plants need water, I have extra water tanks and it will be enough to run in those same gutters. It's just that this system makes it possible not to have to store all the water necessary for watering and at least store some of it in the ground.

Milien61

[sicetaitsimple]

The difficulty is (if I understood correctly) that you will have very little water height between your gutters, I imagine placed on the ground around your greenhouse, and the interior pipes, especially over a length of 18m. It may have a little trouble flowing, more or less irregularly. Except to place the inner pipes lower in a kind of "trench" in the middle of the greenhouse.

[Milien61]

No, the gutters will be at a height of about 90 cm, because I have shutters to open during the summer. The gutters will thus also be in operation in summer so as not to be deprived of stormy rains.

There will therefore be a drop of 90cm between the gutters and the perforated pipes. But as you say the difficulty will still be to ensure that the water is well distributed along the pipe. We will have to play with the slopes, the height of the holes as Christophe said, perhaps even the spacing of the holes.

[sicetaitsimple]

No the gutters will be at a height of about 90 cm

OK, I didn't say anything! That said, it will not be easy to ensure a certain seal between the gutters and the cover of your greenhouse so that the water is effectively recovered.

[Milien61]

I had thought of a strip cut from recycled tarpaulin and this strip would be taped with double-sided tape to the greenhouse tarp while hanging in the gutter. This is what is sold on some sites (but with another means than the double face). To be tested over time if it holds.

[Christophe]

Hello,

Christophe, do you have any feedback on your passive rainwater irrigation system.

Welcome and thank you for your interest!

When it rains, the soil in the greenhouse is wet and there is still water in the chute...so yes after a few months it works...

It didn't work too well this summer due to lack of rain...but it's not the assembly's fault!

[sicetaitsimple]

I had thought of a strip cut from recycled tarpaulin and this strip would be taped with double-sided tape to the greenhouse tarp while hanging in the gutter. This is what is sold on some sites (but with another means than the double face). To be tested over time if it holds.

Yapluska try! In principle it's good, now you actually have to see how it holds up over time.
Good luck. You tell us.

[Ahmed]

The plastic cover of the greenhouses is easily heat-sealed and makes it possible (in particular) to fix a flap to collect the water in a much more solid and durable way than with a double-sided adhesive tape, moreover very unsuitable for this use. I made a metal wheel to carry out this operation: once the wheel has been brought to the right temperature, just apply it to the two thicknesses to be joined, interposing parchment paper (used in cooking) to prevent the plastic from sticking to the metal...

[Milien61]

Well thank you, that's encouraging. I'm planning a drilled horizontal pipe rather than a gutter, to avoid dirt from mulch, earth, dead insects... But for now, it's more complicated to make holes in the right place so that it spills everywhere at the same time. I have to think about that!

Thank you Ahmed, indeed I had thought of hot gluing. Flat on the ground is probably easier. I might give it a try instead. I don't want to burn the tarp. In any case, clever the shot of the heated wheel.