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Why Plastic Mulch?
BLACK, WHITE OR COLORED, PLASTIC MULCH WORKS FOR VEGETABLES

Peppers responded more to silver mulch compared to black, with an average 20 percent increase in marketable fruit yield and fruit size over a three-year study. Lowest yield or marketable peppers were harvested from plants grown on either white or light blue mulch

Tomatoes responded to red mulch compared to black, with an average 12 percent increase in marketable fruit yield and fruit size over a three-year study. There appeared to be a reduction in early blight in plants grown on red.
Yellow has been shown to attract insects � but that can be a good idea. Some growers are using yellow-mulched rows to attract insects to a location where they can be killed,
Blue attracts thrips but has been very effective in greenhouse tomato production
http://www.robertmarvel.com/whyplasticmulch.html

Light reflected from red mulch has a lower red (R) to far-red (FR) ratio than normal sun-
light, while black plastic has little effect on this ratio. The lower ratio has been reported to
enhance the carbohydrate movement into the developing tomato fruit resulting in in-
creased early production. Also, many of the colored mulches, including red, are translucent
and will increase early spring soil temperature resulting in rapid plant growth, earlier
flowering, and fruit maturation.
http://www.public.iastate.edu/~taber/Extension/Progress Rpt 00/redmulch.pdf

Black mulch absorbs most ultra-violet (UV), visible, and infrared wavelengths (IR) of incoming solar radiation and re-radiates absorbed energy in the form of thermal radiation or long-wavelength infrared radiation. Much of the solar energy absorbed by black plastic mulch is lost to the atmosphere through radiation and forced convectio

clear plastic mulch absorbs little solar radiation but transmits 85% to 95%, with relative transmission depending on the thickness and degree of opacity of the polyethylene. The under surface of clear plastic mulch usually is covered with condensed water droplets. This water is transparent to incoming shortwave radiation but is opaque to outgoing longwave infrared radiation, so much of the heat lost to the atmosphere from a bare soil by infrared radiation is retained by clear plastic mulch.

in a pepper canopy, twice as much reflected photosynthetically active radiation (PAR) was measured above clear plastic mulch than above black plastic or bare soil. Although both red and black plastics raised soil temperatures similarly, higher early yields and less foliage were observed in plants grown on red plastic. Both red and black mulches reflected about the same amount of PAR, but red plastic increased the ratio of red:far-red wavelenghts (R:FR) in the reflected light.
http://extension.psu.edu/plants/plasticulture/technologies/plastic-mulches

when tomatoes are grown on red mulch they have higher yields, stronger stems and ripen earlier. Research has also found that red mulch reduces nematode damage.
http://growerssolution.com/PROD/red-plastic-mulch-1-mil-embossed/srmred

While it works ok for some in the northern zones even though there are better alternatives, for those in warmer climates it's benefits are minimal and the risks increase.

There are many discussions about using it all over the various forums here that the search will pull up for you. And the majority of experienced tomato growers agree with bmoser's comments above - the red plastic has minimal if any benefits. It has been tested often.

Dave

I never seen the benefit of plastic mulchs unless your a farm with acres trying to get the cheapest mulch. Other then price and moisture protection, what good is plastic? It doesn't decompose leaving you with rich soil, it doesn't work in harmony with the organisms in the soil, and it is just non sustainable.

I wonder about the toxins in the plastic as well. BPA free drinking bottle ok, but i doubt they make BPA plastic mulch. Or how about the other chemicals in plastic other than bpa?

Plant material for mulch is where nature is now. There's a reason she uses leaves.

As a side note, I don't see the point of commenting in a thread if you don't use the product. All you do is suggest that you're some kind of superior human being - not particularly flattering to yourself. I can't imagine going into an organic gardening thread and telling people that chemical pesticides are a better choice. Just sayin.'

Weed control and moisture retention are nothing to scoff at. And using it can have some real benefits for northern gardeners when used to pre-warm the soil for earlier planting. Organic mulches don't provide that benefit. Even some southern gardeners will use it in early spring for soil warming but then we have to remove it or cover it with organic mulch once summer arrives. That would definitely be required in the OPs zone.

And it sure isn't the cheapest mulch available. So while it isn't recommended by organic gardening purists, that doesn't mean it doesn't have its uses.

Dave

I agree with Dave, using any plastic where and when you have high temps, lots of direct sun, long days .. can cause more harm than good. But places like PNW (where I am) It can have positive effect by warming up the soil early in the season. And I have plans to experiment it this year. The same study indicated that using clear plastic is better than black and it can warm up the soil by as much as 5F(vs. no plastic). That is significant (IMO) early in the season, where and when you have long and cool spring weather. Once it warms up, you can either remove the plastic or mulch over it conventionally. I would prefer to remove it.

I haven't splurged on red mulch but do use the red tomato bags that Territorial sells and I love these! They work great around the tomato cages for many reasons.

I started buying the black/white mulch last season since previous summers had been so hot that brassicas were doing poorly and I just loved it last year. I had broccoli and lettuce all summer and didn't have to weed those crops like usual when I used straw mulch.

I also experimented with black plastic and potatoes this year. They did wonderfully! I have never had a potato harvest like that. Finally I can save my own seed again like I used to, saving me money! It also keeps the potatoes completely covered so no greening. I put straw on top of the plastic to sort of hill it up a little and yields were outstanding.

For me it would be impossible to grow food for 15 CSA shares and a market without plastic mulch, mostly because of weeds but also due to watering, cost and season extension. We all have to come to a level of comfort with organic principles. I rent my land and it is 3 miles away and I hate driving 6 miles a day to farm but I also do almost no tilling and discing and other things that try to make up for it. At the end of the season I can generally fit all the plastic I have to throw away into one garbage bag. I am still looking for a recycling center for drip tape and plastic mulch. The one in MN couldn't make it and closed.

I believe in being conscious about the environment, very much, but i think some people dont realize what things are the real harm and what are not.

Planting earlier from my seedling trays , especially papaya could be a real benefit to me. i plan on having at least a dozen papaya trees and up to 30-40 pepper plants plus a bunch of medicinals, guava, POMs, and other stuff.

i get like 20lb a week of grounds from starbucks, a good bit of grass clippings when summer gets here, but its not enough

JMO

It occurs to me that light colored mulch must be an advantage in areas that get a lot of shading, and for crops that like a lot of sun. Of course, for that same reason, you get more badly sunburned standing on snow than on grass.That being the case, I have to ask. Has anyone looked into using aluminum coated mylar (e.g. space blanket) as mulch? Cheap stuff, and quite durable. It would reflect ALL the sunlight hitting the ground back up. Not very handy if you want to heat the soil, but if you want to enhance the amount of sunlight a plant gets, that would sure do it. It would also, like black much, serve for weed control.

Black and clear plastics were studied on their effect on warming the soil. I have found that to be interestingly useful early and late in the season.

me neither.
sunlight has several colors, and even IR etc...
i am guessing the plant cells only need part of that spectrum to create chlorophyll.
POT growerrs know a lot about this, they use different olor lights

maybe if there is a lot of RED, the yellow is "blurred out" to insects, and they leave it alone?
yellow is known to attract insects...

Black/grey plastics just have low reflectivity but no light can pass through it. So the solar heat will heat just the plastic. Then it can cool off at cold temperature and at night very quickly.

White plastic act more like a mirror, reflecting most of the solar energy.

Clear plastic will let most of the solar energy in, where it will be trapped and will heat the soil under it (greenhouse effect).

Evolutionary pressure is going to make plants that are optimally adapted to sunlight. Not to red light. So there is something a bit fishy about colored mulch. Colored mulch may well have value in repelling insect pests, but ... This is the kind of thing that is easily tested -- with large, double-blind studies. References?

As I said, if you aren't worried about warming the air (black mulch) or the ground (clear mulch), but just want more sunlight on your plants, white or reflective mulch is surely the way to go.

http://extension.psu.edu/plants/plasticulture

Here are my observations based on MY garden (yours may be different):

1) Fairly easy to install. A bit tricky to get it tucked in nice and tight around the edges of the beds as is recommended, but it only needs to be done once. Overall, less work than other mulches.

2) Difficult to control moisture! I know one of the promises of plastic mulch is that it conserves water, but I found it difficult to keep the soil moist, despite adequate rainfall AND me sticking the hose under the plastic at least once each week. I'm sure a soaker hose would work better, but our water is extremely hard and full of iron, so it would foul up a soaker hose in no time flat. So at least once per week all summer, I would turn the hose to a moderate trickle and stick it under the plastic, positioning it between plants so as not to erode the soil around the roots. Move it every 15 minutes or so, when the soil was good and damp. My hope was that capillary action would help transport water around so plants did not have to be watered individually. Unfortunately, whenever I peeled back the mulch a few days later, the result was always the same... dry, dry DRY!

3) No apparent improvement with regard to pests. In fact, squash bugs were even worse last year. Not sure if this has anything to do with the plastic, but..

4) No early ripening of fruits. In fact, tomatoes were later than ever. Then again, many gardeners in the Northeast reported this last year though, so I'm not blaming the plastic. My theory is that the heat wave we had in June sterilized the first round of blossoms, so we all had to wait until Round 2.

5) Black plastic definitely attracts snakes. This could be good or bad, depending on what variety of snakes we're talking about and how you feel about them. I saw them lounging on the plastic frequently and found numerous snake skins under the plastic at the end of the season.

I can accept the snakes (in my case all harmless garters), but not being able to control (or easily monitor) moisture was a real problem for me. Again, your mileage may vary. This is just my experience.

1) One application is as MULCH in true sense, for weed and moisture control . this can be incorporated best with drip irrigation line under the plastic For this application mostly black plastic is used. Then when it heats up you will need either to remove it or top it with another layer of some kind of mulch to prevent heating the soil.

2) Application to assist in trying to heat the soil in early spring. For this application CLEAR plastic is used. As the researched has shown, this method can effectively heat the soil during the day and prevent coolin/maintain heat at night.
This method and application is totally different from (1). This is a sort of micro greenhouse concept for soil that has its place in cooler climates. For example, it would have no use in the southern states zones 8 and higher.

(3) Color Spectrum application: This method is aimed at increasing production I will not get into that area.

My personal interest is in application (2) area. Living/gardening in the cool PNW, I think the use of clear plastic can be very meaningful and beneficial. And I am set to explore and experiment it this coming season.

Plants are green correct? That means that the plants do not absorb the yellow through green spectrum of light, but rather reflect it. What does this leave? IR, red, blue and UV. The red light reflecting off of the mulch provides just those wavelengths (400-500nm) of light that is absorbed by the plant and utilized in photosynthesis.

I still think that given all that, if a plant needs more light, the best mulch is white, because it just reflects more total light. Do that, and let the plant sort out what it wants to use. If you're in a VERY hot area, however, probably best not to increase the total amount of light.

Color is our perception of wave length of the light that is reflected from an object. When we see something green, it means that just that specific wave length is reflected from that object and the rest is absorbed. In other words, color doe not exist as a matter.

Last summer was my "plastic mulch experiment year." I read about all those studies and wanted to find out if they would help my harvest in my garden. Here's what I discovered:

In a nutshell - they were far more trouble than they were worth. Red, green, blue and clear would work fine to heat the soil up if you had no weed-seeds whatsoever underneath. In my garden the weeds were in 7th-heaven under there and grew until they made tents out of the stuff. Black, brown, and the double black/white stuff worked much better for weed suppression. For my northern garden the dark colors actually "shaded" the soil instead of warming it up faster. But once the summer heat hit, it basically cooked everything that is still low enough to be touching (melons especially). My bare (no mulch) tomatoes did not grow any different than the ones that had red under them. (Although Wall-o-waters significantly improved vigor). I used aluminum foil in place of silver and that worked pretty well actually, and I didn't have ANY flea beetle damage on any of the plants it was under. Black/white was my favorite and I will use it for beans again this year. It suppressed weeds (black side down) but reflected light (white side up) and my beans grew really fast, healthy and did not get dirty.

One thing that is an absolute must - You must have an installed drip system underneath the plastic. I thought I could get away with not having it, by leaving bare soil strips between the rows. Not enough. The water just pools on top and then evaporates off.

Also, the colored mulches are very flimsy. Kind of like the real wimpy painter's plastic. The slightest breeze and you will need at least two people to peg it down, and then it still rips free from the pegs.

My plans for this year based on last year's experiments - Wall-o-waters for sure! Black/White under beans and melons. Aluminum foil under eggplants.