Polythene mulch

[Lyn]

I have read recently that clear polythene is better for warming up the soil early than black polythene. Can anyone confirm this?
Regards, Lyn.

[Tigger]

I don't use either, but the farmers here use clear plastic.

[sandersj89]

Yes clear is better for generating heat. It allows the soil to collect heat from the sun far better.

Here is an extract from http://plasticulture.cas.psu.edu/P-Mulch.html:

In contrast, 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. Thus, daytime soil temperatures under clear plastic mulch are generally 8 to 14° F higher at a 2-inch depth and 6 to 9° F higher at a 4-inch depth compared to those of bare soil. Clear plastic mulches generally are used in the cooler regions of the United States, such as the New England states. Using clear plastic mulch will require the use of a herbicide, soil fumigant, or solarization to control weeds.

The only down side is weed seeds will germinate rapidly under clear plastic unless you can leave the plastic in place long enough to cook the seeds.

HTH

Jerry

[Lyn]

Thanks for that info. The weeds are not so much of a problem, as my raised beds are relatively small, and half-an-hour's hoeing should cope with the weeds.
Regards, Lyn