can actually damage the polycarbonate panels and
make them less transparent.
After using soapy water and/or the pressure
washer, it is a good idea to further sanitize the green-
houses with a sterilizing/sanitizing agent. A diluted
bleach solution is one sanitizing agent commonly
used by greenhouse horticulturists. However, there
are two distinct disadvantages to using a bleach so-
lution. First, the odor and fumes created by bleach
can be overwhelming, especially when used in a
contained area like a greenhouse. Second, a diluted
bleach solution works fi ne for sanitizing the green-
house itself, but should not be used on the plants
that will be coming into the greenhouse from outside.
Even a diluted bleach solution would be harmful
to the plants. Molds and pathogens often enter the
greenhouse by hitching a ride on a plant or in the soil
of a plant brought in from outside.
A good solution to this is a cleaning agent called
Physan 20. Physan 20 is an algaecide, fungicide,
bactericide, and virucide. In other words, Physan 20
helps fi ght algae, fungi, bacteria, and viruses. After
washing the greenhouse with soapy water, an ap-
plication of Physan 20 will kill any remaining fungi,
algae, bacteria, or viruses. Physan 20 is virtually odor-
less which makes it much easier to work with than a
diluted bleach solution. Perhaps the largest advantage
of Physan 20 is its ability to be used directly on orna-
mental plants and their soil. Physan 20 can be used
as a soil drench to kill any pathogenic fungi, bacteria,
algae, or viruses lurking in the soil of plants kept out-
doors. Physan 20 comes in a concentrate form and
Milwaukee Instruments - Manufacturing A Complete
Line of Growth Media Diagnostic Equipment For
Use In Greenhouses & Hydroponics
See all our Instruments at - www.milwaukeeinstruments.com
28
www.GardenandGreenhouse.net
November 2017