Mulching with Black Plastic - Question

If the purpose of mulching is to slow evaporation and to warm the soil, why wouldn't black plastic be ideal?  Seems to me that stretching plastic over the beds before delineating the squares would be quite easy.  Then slits in the areas you transplant or plant you seeds and Bob is your mother's brother.  When the plastic gets too rent by cutting slits, it would be easy enough to remove and replace; and even replacing it once a year would not be too expensive.

What do you think?  What have I missed?

I'm in a hot zone. If I used black plastic over the MM, I would have steamed veggies! This is what I think. Mulching with a plant product (wood chips, bark chips, straw, pine needles, etc.) slows evaporation, but its main value is that it shades the soil from the sun. The roots are kept cool. You can also move the mulch aside and check out the plant stem and see what insect, larva, may be lurking around it.

And you are nearly eliminating the most precious ingredient to any garden...rainfall.  Nothing will perk up anything growing better than rainfall.  Sanderson is spot on as well. JMO.

sanderson wrote:I'm in a hot zone.  If I used black plastic over the MM, I would have steamed  veggies!  This is what I think.  Mulching with a plant product (wood chips, bark chips, straw, pine needles, etc.) slows evaporation, but its main value is that it shades the soil from the sun.  The roots are kept cool.  You can also move the mulch aside and check out the plant stem and see what insect, larva, may be lurking around it.

Yes, that makes a great deal of sense.  I, too, am in a hot zone.  A couple or 3 years ago we had over a hundred triple digit days and one period of more than 2 months with triple digits every day.  That would certainly overheat the soil.

The good news is that I went to a local home and garden expo today and found sources for mulch and for compost!!   

In my cool climate I use black plastic just as Rabbithutch suggested.  I love the stuff.  

However, I did learn the hard way not to plant corn seeds under it.  The plastic provided warmth, dryness, and safe working conditions for the field mice who ate 95% of my corn seeds one spring!

boffer wrote:In my cool climate I use black plastic just as Rabbithutch suggested.  I love the stuff.  

However, I did learn the hard way not to plant corn seeds under it.  The plastic provided warmth, dryness, and safe working conditions for the field mice who ate 95% of my corn seeds one spring!

Boffer since our climate it pretty much the same   would black plastic help with trying to grow melons? and if it would .....how much black plastic would you suggest we use around the plant?  does it help with tomatoes?

Im thinking those two things is what we would use the most with for heat loving veggies....is there any other veggies or fruits you have used the black plastic with and found better results by using it?

hugs
rose

I don't know if we could get our soil too hot!  I think that any warm season crop would benefit.  I know that it helps my squashes grow better than in boxes.  Here's a couple squashes next to a trellis.




I used black plastic in lieu of 'hilling' potatoes last year.  It was easy, and I only got a few taters with green ends.

thanks so much Boffer for the pics! now I have an idea of how you use the black plastic....do you buy it by the roll at one of the big box hardware stores?....if we were going to use it in a smaller area....could we use a black plastic bag that is used for collecting leaves and such?

thanks again
hugs
rose

I always have a roll of 6 mil plastic around, in black and clear.  Big box stores have them.

Black plastic bags will work fine if you don't walk on them.  

You can find lots of discussions on the net  about what color mulch works best for tomatoes: black, clear, red, or other.  I have no clue if there's a difference.

thanks again boffer! I really appreciate all the time you take to help us out!!  we will keep ya posted on how it works out for us   I want to give it a try for melons at least

hugs
rose

You also restrict soil oxygenation with black plastic.

In Inland SanDeigo county I routinely planted corn and squash through a black plastic. I ran drip hose down the rows first for watering. We did not get summer rain there. It did not seem to bother the plants at all, but corn likes heat and as the season progressed provided its own root shade. Here in Montana I plant tomatoes and squash and such through black plastic, even in the green house. Anything to help warm the soil.

Boffer, It looks like you have some sizable "breathing / planting" holes in the plastic. Plus the cooler earth is below the compost. I see why it works

Marc Iverson wrote:You also restrict soil oxygenation with black plastic.  

How do I measure soil oxygenation?
At what levels does it become a problem?
What are the symptoms?

boffer wrote:

Marc Iverson wrote:You also restrict soil oxygenation with black plastic.  

How do I measure soil oxygenation?
At what levels does it become a problem?
What are the symptoms?

yes please, do you have a link to a page that explains this Mark?

I've used plastic to warm up a bed or two after a long, snowy winter and it works well.
It also helps with a rainy spring, keeping the torrents from making my beds a mire of mud so I can plant earlier.

I wish I could try one hill, Boffer.  You've got me curious.  Of course, I can't, as the new compost bin got the last spot left in the tiny back yard  I got to thinking about what the local farmers do, they have long elevated rows of black plastic for the strawberries.

One of our OSU lecturers told us that a few weeks ago. We weren't supplied links on it, but Oregon State University, under whose auspices the Master Gardener's program is conducted, has a lot of material online.

Next time I'm doing greenhouse hours, I'll try to remember to ask about measuring soil oxygenation. There's a mentor there who was authorized by the program to do soil tests, and also runs a side business doing custom testing. I"m not sure whether people ever ask him about soil oxygenation, but it would be interesting to hear it straight from the horse's mouth, if so.

All I can do is pass on what I hear in our lectures and read in our textbook, but I'm no agricultural scientist myself.

Our lecturer did say that black plastic became a big new thing in the 70's, but that the science has moved well on from endorsing it. And he IS an agricultural scientist.

Thanks Mark. I'm glad you are learning a lot in your MG classes but it is always helpful to post a link for those of us left wonder. I often try to post links so that others may learn.

Here is a link that offers some pros and cons of various mulches including black plastic.
http://www.ext.colostate.edu/mg/gardennotes/715.html

the soil needs to air out...black plastic mulch has disappeared from the landscape industry in favor of other material that breathes...lets air and water pass through.

From camp's link:

...The plastic fluttering in the wind pumps air into the soil. However, covering the plastic with organic mulch like grass clippings or chips could reduce soil oxygen levels...

Interesting...

that Colorado site is a jewel.  I had to bookmark it to go back and read more later. 

The site said to NOT use wood chips or bark in the beds! But at least it explained why. My take is to read scientific or expect articles keeping in mind the method one uses (SFG).

boffer wrote:From camp's link:

...The plastic fluttering in the wind pumps air into the soil. However, covering the plastic with organic mulch like grass clippings or chips could reduce soil oxygen levels...

Interesting...

The plastic fluttering pumps air into how much of the soil? Compared to how much air it blocks?

I haven't seen a lot of fluttering in the plastic sheeting I've seen. It's been put down pretty tight and the openings were pretty small.

Marc Iverson wrote:

boffer wrote:From camp's link:

...The plastic fluttering in the wind pumps air into the soil.  However, covering the plastic with organic mulch like grass clippings or chips could reduce soil oxygen levels...

Interesting...

The plastic fluttering pumps air into how much of the soil?  Compared to how much air it blocks?

I haven't seen a lot of fluttering in the plastic sheeting I've seen.  It's been put down pretty tight and the openings were pretty small.  

Beats me! The wording makes it sound like it's a cheap air compressor!