UV Air Filters for Greenhouses

Hi, folks,

What with all the problems with mildew last winter, I’m thinking of getting a UV air filter for the greenhouse. Supposedly the UV will kill all the airborne spores. Has anyone tried this? If so, does it work? If not, is it likely to? If it only helps a little, I think, it might be worthwhile.

Hi, Fara,

I don’t know anything about those filters.

But I do know fungal spores. Once upon a time, I was a palynologist and I know fossil fungal spores, the ones we removed, in tact, from solid rock with a sucession of concentrated acids (HCl, HF) followed by heavy liquid flotation with ZnBr. The spores emerge from treatment undamaged. Fungal spores are less than 10 microns in longest dimention. But the really odd thing, the thing that sets them apart, is the thickness of the fungal spore walls. Two to three microns thick. Now maybe UV light can penetrate those walls…I can, however, envision those walls having reflective AND refractive properties…if the wave of light could last long enough to be directed. I could see UV damaging hyphae which are much thinner walled.

(Sometime ask me about people eating pollen.)


I have never seen these devices.

Make sure there is no risk to the user from the UV radiation level emitted.

Hi Fara,

When I get powdery mildew, I really try to spread it around rather than get rid of it. I want to know which roses are resistant. If a very unusual rose gets a mild case of PM, I’ll save it, but any seedlings with moderate to heavy PM are culled. It really pays off in the long run to eliminate disease prone roses early on.

Jim Sproul

Jim said,

“It really pays off in the long run to eliminate disease prone roses early on.”

I agree. It really does!


Very interesting information! May be part of the reason why I’m so violently allergic to mold spores!

Jim and Robert,

Thanks much. Very good advice on the whole, but I’m in a peculiar circumstance. My interest in rose breeding is mostly academic, and in order to get statistically significant results, I need as many seedlings from a particular cross to live long enough to bloom as possible. Once I can see the mature bloom and take notes, I immediately cull any that mildew.

And I was wondering if one of those UV things would just overall make it more comfortable for me to work in the greenhouse. I sneeze enough as it is; much worse in there! :smiley:


Fara, perhaps I misunderstood your post, but if you are talking about a UV (ultraviolet) filter, it doesn’t filter the

air, it purports to sterilize it. The spores will remain in

the air, and will still cause allergic reactions. I wouldn’t

bet all the spores are killed, either, as Ann hinted.

What you probably need is an electrostatic air filter, which

actually removes allergens from the air. The one I have is

constantly messaging to change the filter, even right after I

have done so.