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Why light transmission is so important

Why light transmission is so important

Not cleaning your roof reduces income potential


I took this photo last week. When I viewed it closely on my computer I was surprised.  While I was looking up taking the photo I could see the glass was dirty, but with the naked eye it honestly did not appear to be as dirty as the photo suggests.  However, this glass is in need of cleaning and this image definitely illustrates that.

As we are approach the end of March, light levels are decreasing.   In April the natural reduction of light, penetrating to your crops, will negatively impact on production.    One percent reduction in light equals less production.  Fifteen percent reduction in light equals a LOT less production.  The problem equating the loss of light with a loss of production is difficult because it is not always measured.  For example, if you never had the production in the first place how do you know you have lost production.  Well that’s easy to answer, you have.  Growers that keep historical production figures will have an advantage if their crop cycles are similar each season. 

There are a few issues surrounding cleaning greenhouse roofs, and one of those concerns is the health and safety requirements for staff when cleaning.  I have been attempting to find an answer to this concern, the possible solution found is in the trial phase.  Currently, the only option, if you don’t have an automatic roof washer, is to climb on the roof with your hose and brush and give it a good old scrub.  There are companies that specialise in water blasting and cleaning glasshouse roofs but the cost of this can be off putting for growers. However, this concern should be counterbalanced with the potential loss in production.  As an advisor I want your roof clean for the best possible light penetration.  This is another reason why I am so keen on the anti-condensation coatings. 

Winter is approaching, within reason your heating bill will be the same if your greenhouse roof is clean or not.  In the past cleaning your roof was an annual job that was a “must do” now it seems to be a job that is put in the “too hard basket”.    This does affect smaller grower’s more than large companies, as larger companies own their own automatic roof washers that clean their greenhouse roofs multiple times a year. 

Personally, I never liked doing this job and possibly don’t have the nerve for it anymore (let a forward pack run over me any day of the week, like they used to!) but there are companies that have specialised teams that carry out this essential task on your behalf.


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Article Written by Stefan Vogrincic, Consultant, Grower2Grower

Article Edited by Marie Vogrincic, Editor, Grower2Grower