My city garden has some dark areas, especially along the south and west fences, only getting sun in the mornings. There are no trees in the mix, it's just the fence shadow. It's a bit of a problem for good growing in the such a short growing season that I have here in Zone 3 land. This garden is edible and medicinal mix. All the shade loving stuff is in the front yard.

Anyone have any tips and tricks for using mirrors in the garden to improve light for plants? My plan is to put mirror(s) with sealant on edges and back to protect, on the shady walls. Not in the hot sunny area, bouncing concentrated light in.

Somewhere in my youth I learned that a mirror only reflects one seventh of the light that hits it.  That's fine to see your own face but plants thrive on the intensity of warmth and brightness that lands on them.  I don't know for sure that the one-seventh number I learned as a kid is accurate -- perhaps modern materials science can improve on it -- but I would worry that the mirrors may not have the positive results you hope for.

But they look lovely at the ends of paths with trellis around then to give a huge sence of space. Cant hurt to try if you can pick up one off an old wardrobe. Good luck.
Im a scientist but I dont remember the 1/7 thing, but I wasnt a very good scientist. Clearly!

It might be more effective to use what is called first surface mirrors. They are generally expensive but will reflect most of the light. A first surface mirror has the reflective material on the outer glass surface rather than underneath the glass.

I had not know of the 1/7 bit, that's interesting, Dan. And Mandy, I am with you on the lovely effect a mirror can have in the garden. It's quite stunning actually. I'll be researching the first surface mirrors, for sure, Mike. Is there a specific source for them? Thanks!

An electronic recycler is a good place to start. Someplace that has old photocopiers (Xerox) or other types of equipment (photolithography tools used to make semiconductors & some medical equipment) that uses light.

Also, some of the old style large screen projection tv's used them. Those are often available on Craigslist. Snag the fresnel lens while you're at it!

A couple other things to maybe consider. Would birds see their reflections and maybe fly into the mirrors? Could you have concentrated reflections of light and possibly "burn" a plant (prism effect)? Would neighborhood kids take to throwing rocks at the mirrors?  I'm sure the concept would be (at least somewhat) helpful, but the unintended consequences may cause difficulties. ~~Would it help to paint the fence white to get more light reflection into the space than you would have off a dark fence?

Hah! Mike, like your sourcing from old items. I never knew such quality stuff was locked in the bowels of these old machines.

Hi Jim, I have definitely thought of the birds and will be placing them lower down, not in flight paths, with plants in front. Mirrors seem to be a great draw for birds. Apparently they can get quite enamored with their reflections. I'm curious to see which birds get most interested in this way. And my backyard is secluded from the street. No back alleys. The yard is abutted to 3 other yards, no kids, 6-foot fence. I do like your idea of the paint. That can make a huge difference.

I find that mirrors don't reflect that much light.  Or rather, they reflect a fair bit but only in one direction.  In my house, anywhere there's a mirror, it kind of looks like a dark hole in the wall.  Unless the sun is shining in a window, onto that mirror and then directly at me.

White surfaces, on the other hand, seem to bounce light around very well.  So even if the sun angle wouldn't reflect sunlight at your plants just right, a white "mirror" would still send it their way.

The farm I work at has a few rolls of something similar to this https://www.amazon.com/Black-White-Poly-Film-5-5-x/dp/B000I2ZXQG

We just put some down today as a cover in a tomato area (weed control) and put it white side up for the reflective quality

Hmm.

Jim, Mike, and Ty's comments make me think white may be the way to go. However, there are some issues with how to accomplish this the best way because I don't want to shift the balance of the fence wood by painting only one side. I butt on 3 yards, including against buildings, so painting the opposite side even with neighbour agreement doesn't work out that well. Which can lead to bowing of the wood when only one side is painted.

I'm curious, Ty, the product description link you put up reports 90% reflectivity. Is this product different from your normal black and white garden material? I'm not super familiar with poly film.

And I'm also still garden mirror curious. So will likely experiment with that too.

I'm so glad life is always interesting. A garden guarantees that.

I have some old mirrors in my garden- my chickens seem really amused by them! I don't use them to try and reflect light to plants though- just for aesthetics. I also have some sheets of mirrored acrylic (instead of glass) that are much less breakable!

I haven't tried it but one of the greenhouse things I read was using mylar christmas wrap stretched on wood frames as mirrors on the back wall   They had gone that route rather than space blankets because the christmas wrap was more reflective.

Viola Bluez wrote:
...I'm curious, Ty, the product description link you put up reports 90% reflectivity. Is this product different from your normal black and white garden material?...

Hopefully I can remember to ask the owner some more questions about the material today! I just started on the farm 4 months ago and still have a lot to learn on my end :)

...so I asked, but don't have any more info about reflective properties, or how that 90% rating compares to what we used - she said she's had it for a couple years and just doesn't quite remember what exactly it is  

Gotta be something similar though and maybe you can find a much smaller sheet/roll for very little $.

I would try to avoid painting, like you said anyways. Draping white plastic probably wouldn't look so great, so I don't know but - like the latter posters mentioned there are other mirror-like options that seem much lighter, easier to install, and safer than actual mirrors to me.

Thanks Ty, and thanks everyone! Lots of excellent ideas to try out.

An update:

The reflective rolls that Ty mentioned seemed to work best for me. I trialed a long sheet between fence posts. It did well, with wind being the only issue, ripping the material away from the staples along the bottom. I put in a board that I had nearby to hold it, then stapled again and it stayed, but did lose some reflectivity, so I'd likely make up specific frame pieces to pin it down better in the future. No issues with birds, as it's reflective, but not in a mirror way.



I also did try a mirror, but it really didn't seem to brighten things up much. And I did purchase two first surface mirrors, but they're really small (all I was willing to spend) and so don't give the reflectiveness the big rolls do.