Increasing sun exposure

[JoP]

Hi all,

I have a row of grapes next to a fence with less than 8 hours of sun exposure per day.

I’m thinking to place a reflective Mylar sheet on the fence to increase sun exposure.

Has anyone done something like this, can you share your experience or opinion on this?

Thanks

 

[salcoco]

definitely require more sun exposure. if Mylar sheet will do it is unknown

 

[JoP]

definitely require more sun exposure. if Mylar sheet will do it is unknown

Mylar sheets are commonly used in greenhouses with grow lamps.

In the case of grapevines, there is a danger of burning the fruit if too much sun light is reflected.

If someone tried it, I would like to know.

Thanks

 

[Obbnw]

I've been playing around with reflective mylar. I've got a west facing piece and it definitely created hot spots in the late afternoon but in the photo below, the


corn under it does seem to be bigger. It is hard to keep flat and smooth. It was relatively cool this morning and I think the expansion and contraction of the substrate makes a bigger difference than I would have thought. I put the mylar on a piece of foam on a hot day. It was pretty flat when first done but has loosened up. In the heat of the day some of the wrinkles flatten out quite a bit.

One thing I did not know is that water can wash the reflective coating off. If there is standing water the reflective layer just dissolves. In the picture below I put some behind glass, if you look close in the middle of it the reflective layer has dissolved from the little bit of water that got in during rains. The one above the corn seems to do better since it doesn't get standing water but the quality of the reflection has changed. This one wall also perfectly flat when first done but has developed wrinkles.

 

[JoP]

I've been playing around with reflective mylar. I've got a west facing piece and it definitely created hot spots in the late afternoon but in the photo below, the
View attachment 62495

corn under it does seem to be bigger. It is hard to keep flat and smooth. It was relatively cool this morning and I think the expansion and contraction of the substrate makes a bigger difference than I would have thought. I put the mylar on a piece of foam on a hot day. It was pretty flat when first done but has loosened up. In the heat of the day some of the wrinkles flatten out quite a bit.

One thing I did not know is that water can wash the reflective coating off. If there is standing water the reflective layer just dissolves. In the picture below I put some behind glass, if you look close in the middle of it the reflective layer has dissolved from the little bit of water that got in during rains. The one above the corn seems to do better since it doesn't get standing water but the quality of the reflection has changed. This one wall also perfectly flat when first done but has developed wrinkles.

View attachment 62496

Obbnw, thanks for sharing your experience.

Most of the Mylar sheets are 2Mil thick, but there some that are 6 Mil, perhaps they would stand up better to wrinkling.

Also some have a diamond pattern to defuse the light.

Regarding the coating wash off, I didn’t know that.

As far as rain goes, here in California it is not much of a concern in the growing season.

 

[wood1954]

How about placing crushed white limestone rock underneath the plants

 

[JoP]

How about placing crushed white limestone rock underneath the plants

That should help also, besides the reflective quality; they store the heat for later when the sun is gone.

I have seen a picture of grapevines at Châteauneuf-du-Pape where huge rocks are all over the vineyard under the vines and they mention just that.