Using Mirrors in coldframes, etc?

[BrandNewDay]

I was wondering.... has anybody ever tried putting mirrors behind plants in coldframes or leantos to maximize light? I ask because we're probably going to build our own coldframes and won't be able to make the sides glass (that's beyond our abilities.) I thought maybe putting some old mirror tiles in the bottom might increase the amount of light within. I also thought it might be useful for when we grow seedlings on our north windowsill to put mirrors down and increase the light.

Is that a totally daft idea?

[BFG]

It should work well. Some people use foil covered cardboard or similar on window sills. I use my window sills for growing and have been meaning to try it myself.

I think I'll try cardboard painted white and one with foil and see how the plants react.

It can't hurt!

[BFG]

I've also been toying with the idea of painting my back fence white to reflect the light around, but not sure whether it'll look silly or not.

[Sweepster]

I have one of those polycarbonate coldframe thingies, and taped flat pieces of polystyrene (from packaging), covered with foil, against the back and one of the sides since it doesn't get an enormous amount of light where it is - in winter I used polystyrene inside all four walls to insulate it a bit. Mirrors might work well, though I'd be careful about them catching direct sunlight and possibly burning plants.

[Bren In Pots]

Ever since I've been using foil covered cardboard in my window bottoms I've not had my plants go leggy so I'm sure it will work in a cold frame. Don't think I'd use mirrors though.

[bramble]

BFG, I painted the wall behind my greenhouse white when I cut down the hedge and the ammount of light and brightness was unbelievable'
I say, go for it.

[Snadger]

Not to put the mockers on what at first seems a good idea but................

Will mirrors not focus the light similar to a magnifying glass and burn plants? White or semi reflective coverings deffo work though!

[BrandNewDay]

I don't think mirrors focus light like a magnifying lense. They simply reflect it. The light hitting a mirror is the same light that just passed through the glass. The angle of the mirror can deflect it in different directions, and it can result in some surfaces getting nearly twice the light (sunshine and reflected light) but that might not necessarily burn a plant.

However, a mirror directly under the plant would deflect light upwards. Unless further mirrors above caught it and cast it back down again onto the upper surface of the leaves, which are already getting the first pass of light through the glass, I don't think you'd see areas of double sunlight.

[Snadger]

I don't think mirrors focus light like a magnifying lense. They simply reflect it. The light hitting a mirror is the same light that just passed through the glass. The angle of the mirror can deflect it in different directions, and it can result in some surfaces getting nearly twice the light (sunshine and reflected light) but that might not necessarily burn a plant.

However, a mirror directly under the plant would deflect light upwards. Unless further mirrors above caught it and cast it back down again onto the upper surface of the leaves, which are already getting the first pass of light through the glass, I don't think you'd see areas of double sunlight.

I'm probably wrong but know you can shine a light in someones eye by varying the angle of a mirror...........just thought the light intensified may have an effect on foliage?

[BFG]

You could even put mirrors or something white (matt is surprisingly better than gloss) or reflective on the floor as well (maybe at the back?).

I've never tried it, but read that as most sap sucking bugs like the dark (hidden) underside of leaves, reflecting light up at the plants deters them.

[BFG]

BFG, I painted the wall behind my greenhouse white when I cut down the hedge and the ammount of light and brightness was unbelievable'
I say, go for it.

I'm tempted. Not sure if it'll be too harsh/bright. And it's not even my fence, but if it'll look okay.....

I need to do some photo editing and see what it'll look like.

It would be brilliant if I could. It's south facing and I've got a Plum/Almond, Pear and Apple tree right next to it and I'm thinking about putting a grape vine in. They'd love a load more light.

I don't suppose you have a picture of your garage do you?

[Welsh Wizard]

Basic biological science usually teaches Blackman's law of limiting factors.

Limiting factor

Definition

A factor present in an environment that controls a process, particularly the growth, abundance or distribution of a population of organisms in an ecosystem.

The concept is based upon the Law of the Minimum, which states that the functioning of an organism is controlled or limited by that essential environmental factor or combination of factors present in the least favorable amount that may not be continuously existing but only at some critical period of time.

Essentially a plant will thrive if all its needs are met. If one of its needs are not met than growth will be limited by this factor.

So, if the limiting factor in your cold frame is lack of light, then increasing light level with mirrors will have a positive effect on growth of the plants therein. But this will only hold true if there are no other limiting factors such as water supply, CO2, NPK and trace elements. Your effort as a gardener should be to remove as many limiting factors from the plant as possible to allow the plant to flourish and (hopefully) give a useful crop.

[Snadger]

Basic biological science usually teaches Blackman's law of limiting factors.

Limiting factor

Definition

A factor present in an environment that controls a process, particularly the growth, abundance or distribution of a population of organisms in an ecosystem.

The concept is based upon the Law of the Minimum, which states that the functioning of an organism is controlled or limited by that essential environmental factor or combination of factors present in the least favorable amount that may not be continuously existing but only at some critical period of time.

Essentially a plant will thrive if all its needs are met. If one of its needs are not met than growth will be limited by this factor.

So, if the limiting factor in your cold frame is lack of light, then increasing light level with mirrors will have a positive effect on growth of the plants therein. But this will only hold true if there are no other limiting factors such as water supply, CO2, NPK and trace elements. Your effort as a gardener should be to remove as many limiting factors from the plant as possible to allow the plant to flourish and (hopefully) give a useful crop.

Phew!!!!