Disinfecting and winter cleaning

[Cole_Robbie]

I was planning on not using my greenhouse until the early spring, in the hopes that a winter freeze would help to kill bugs and disease inside. But now I'm reading that Early Blight spores are not killed by freezing. I was planning on doing some cleaning and disinfecting anyway, and I'm trying to pick out the right products.

Diluted bleach is cheap, but I think it would be corrosive to the greenhouse plastic. I can still use bleach for the gravel floor, benches, and pots. I have a pressure washer I can spray the gravel with if that helps.

Physan 20 is sold in the catalog I order most of my supplies from. At $6/pint, diluted to 2 tbls/gal, it is not very expensive. I'm hoping that it won't hurt the greenhouse plastic. I might check with the manufacturer just in case.

I also have to remove the diluted latex paint that I sprayed as a shade coating. From what I read, a basic dish soap like Joy or Dawn will work to remove the paint without damaging the plastic, as long as only a soft rag, brush, or sponge is used.

If anyone has suggestions beyond the bleach and Physan, I am all ears. Thanks!

[GeneMN]

I've heard (WPR radio show) that soap solution is about as effective as bleach and much less damaging to things. Not familiar with Physan; will look it up.

I've been thinking about how to disinfect my greenhouse. I use it winter and summer ('solar' with a big bag of water in the back) as it is my greywater treatment. Works well in the winter for kale and asian veges as well as baby greens in hanging troughs. The Winter Greenhouse people let their greenhouse go hot in the summer to treat some meanies, but I have been using it for tomatoes, peppers and cukes with great success. Treated aphids with parasitic wasps, and trim any moldy leaves. But I'm wondering when the buildup of disease organisms will catch up with me (two years now...knock on wood).

I can try a wash down with soapy water on the polycarbonate glazing and hard surfaces, but not sure what to do about the soil, or if anything can be done.

Hoping for some more responses.

[clkeiper]

Peroxide is very effective. It is sold by the gal in hort. grade at a 35% solution and you have to dilute it. But be very careful to not get the 35% on you as it is caustic. I buy it at my greenhouse supply place for $10.00 a gallon. I put 1 1/4 c of peroxide and 14 3/4 c water for a gallon of diluted mixture )or put your peroxide in a gal. container and fill with water). I sometimes use more peroxide for cleaning really mildew/algae covered pavers or the lexan. Spray it on and wash the lexan with a cloth or scrub the floor or other hard surfaces with a scrub brush or broom. Let it air dry.

[JamesL]

Originally Posted by clkeiper

Peroxide is very effective. It is sold by the gal in hort. grade at a 35% solution and you have to dilute it. But be very careful to not get the 35% on you as it is caustic. I buy it at my greenhouse supply place for $10.00 a gallon. I put 1 1/4 c of peroxide and 14 3/4 c water for a gallon of diluted mixture )or put your peroxide in a gal. container and fill with water). I sometimes use more peroxide for cleaning really mildew/algae covered pavers or the lexan. Spray it on and wash the lexan with a cloth or scrub the floor or other hard surfaces with a scrub brush or broom. Let it air dry.

Carolyn,
Is there a brand name associated with H2O2 you are buying? And are you sure it is 35%?
That is a really cheap for a gallon. Haven't been able to find it anywhere that cheap.
I paid $17 for 16oz of 35% food grade H2O2.

[Cole_Robbie]

I bought some 35% once when I lived in Tampa. I had to go to a chemical supply company.

[JamesL]

you can get the 35% food grade at the health food store.
Apparently people drink it diluted. Touted for a whole host of health reasons.
No clue if they are accurate....

[clkeiper]

Yep, I am sure it is 35%. I have gotten it on me and it makes burning white skin patches. I do know that it is the cheapest price I have ever found, but it is run by an Amish family, so there isn't any marketing overhead for the place. VERY utilitarian. it comes in a plain opaque jug that has no writing on it so I assume they are re bottling it from a drum.

[JamesL]

Thanks. That makes sense.

[greentiger87]

Soap doesn't actually disinfect very well, it just physically removes material and allows it to be rinsed away. Meaning it's great for washing your hands, but a wet soapy sponge left on the counter will quickly become a breeding spot for (usually harmless) microorganisms. Bleach or peroxide work really well *when the object is already clean*. Bleach is really sensitive to excess organic material - that's why the directions always say to clean the surface first before you use bleach as a sanitizer. Hydrogen peroxide is not quite as sensitive as bleach, but is still ineffective as a sanitizer if there are visible organic stains/soils.

In the home brewing world for example, hobbyists are often encouraged to think of bleach or other sanitizers as "insurance" rather than their first line of action. If a container is cleaned extremely thoroughly with hot water, bleach really is just icing. If you physically remove the organisms, there's not much left to kill - and what is left is isolated, probably very physically stressed, and very susceptible to oxidizers like bleach.

As for your soil, do you actually have a soil-borne disease problem you need to deal with? If it's an issue of airborne/waterborne spores.. a really heavy mulching may be all you really need.

If you have soilborne disease, take a look at biological soil disinfestation. It can be as easily as incorporating some nitrogen and microbe source (cow manure), and saturating with a sugar solution or 1% ethanol.

[Cole_Robbie]

The current high tunnel has a gravel floor. Mostly I'm worried about dead plant leaves that have fallen into the gravel spreading fungal spores to next year's plants. The soap will be for washing the diluted latex paint I sprayed on the outside plastic as summer shade. I'm sure I'll end up using the pressure washer to get the paint off, very carefully that is.

[greentiger87]

Sorry Cole, I was getting confused between you and GeneMN.

I know it feels good to do it, but I doubt spraying down gravel floors with bleach really does anything :/. I'm guilty too, I spray the soil with bleach before I mulch.. it's just a psychological thing. It's inactivated almost as soon as it hits easily oxidized organic matter. I even spray Daconil on the ground sometimes, which makes absolutely no sense.

Physan should work, as quaternary ammonium sanitizers are still pretty effective in the presence of organic material.

You could also consider a leaf blower or garden vacuum.

Afterwards, you could probably speed along the decomposition of whatever debris is left. You'd need a carbohydrate source, a nitrogen source, maybe some microbial inoculant.

Actually, since we're talking about fungal spores.. wouldn't horticultural oil or vinegar both work pretty well? That would be very cheap, and no worries about toxicity or ineffectiveness in the presence of organic matter.

[bower]

Last year I had to figure out how to disinfect my greenhouse after a really bad year.

You have to start by removing all the plant material, which is where the disease spores overwinter. I dug out the roots as well, except for small bits the worms would take care of. I picked out any dead leaves or debris I could find in the gravel floor and also turned the gravel a bit so anything I missed was not laying on the surface.

I used bleach in hot soapy water to wipe down smooth surfaces - the outsides of the tubs, and to clean all the trellis material (bamboo and sticks) which I removed to a warm room indoors to dry out as well, and then treated with linseed oil before reusing it this year.

I used soapy water to deal with pests that winter in the top soil layer and on dormant trees (miners, mites, thrips). Murphy's Oil Soap is equivalent to insecticidal soaps which are much more expensive. I hosed down everything with warm soapy water. I used a warm soapy soil drench before turning the soil so that the top layer was deeply buried as well. I splashed buckets of soapy water over the stone and gravel floor as well.

When I reconditioned the soil in the tubs, with kelp sushi and fresh compost and lime, I found lots of worms were still well and at work, not affected by the soaping. They ate up all the tomato root residues.
BTW, garden lime also works to rid the soil of algae or moss.

I planted this year's tomatoes in the same containers in the reconditioned soil where the previous year there was Early Blight and Botrytis mold galore. There was really no recurrence of the EB - I had two susceptible plants that had some but no general infection of lower leaves. Botrytis did affect some of the plants later in the season after the main crop was already set or done, but like EB it's in the environment here so afaik the source was open windows, not anything left over in the greenhouse. My plants were overall very healthy and set a great crop. So I will do the same or similar sanitation and soil reconditioning routine this winter.

[dice]

For the latex paint on the plastic you could try a cleaner with
d-limonene. I used a commercial one to clean dried latex drips
from brushes and rollers off of a polyurethane-coated floor.

Here is a gallon qty from Amazon:
http://www.amazon.com/Greensense-Cit.../dp/B00025H2GI

This is one that I actually used for this:
http://www.shopbrodart.com/supplies/...-126-Oz-Spray/

No damage to the polyurethane floor coating. I did need to scrub
a bit, but the dried latex came right up.

Potential health hazards of d-limonene containing cleaning
compounds:
http://thegreenists.com/going-green/...are-they/10527

(Workaround: wear long chemical-resistant gloves and wipe it on
with a cloth or sponge rather than spraying it. I did not notice any
skin irritation from De-Solv It, but I may have had gloves on.)

[ArthurDent004]

I ran across an article on the different things you could use as a disinfectant and how corrosive they can be to certain materials. The author used Lysol (the original, phenol-based material) for cleaning gardening tools, pots, pans, and other surfaces because it was less corrosive than a bleach solution and easier to handle. If you buy the concentrate you can get nine gallons of standard strength Lysol from a 12 ounce bottle or you can mix it to your desired strength.