Bleach solution (soaking pots for re-use)

[Fairorchids]

Regular bleach is sold in a 5.25% concentration. In the past I have heard people say to use a 5% bleach solution, but I do not know anyone using full strength bleach to soak old pots.

In an old thread I found one recomendation, to use 1 part bleach to only 1.1/2 to 2.1/2 parts water.

Diluting the bleach with:

19 parts water = 0.25% bleach in solution
9 parts water = 0.5% bleach in solution
1.5 parts water = 2.0% bleach in solution

Does anyone know of a rigorous study of this question?

I would cosider using close to full strength bleach, if I could re-use the bleach, but bleach 'evaporates' out of the water if left standing in an open container (reportedly at 0.75 g/day). 1 gallon contains about 295 g of sodiumhypochlorite, so it should be about inert after 13 months (and obviously be progressively less effective over this time line).

I guess pouring it back in the jug would eliminate the evaporation, but it is a lot of handling of a fairly nasty liquid.

[RandomGemini]

I use a half cup of bleach to a gallon of water. I figure, a quarter cup is considered sufficient to sanitize a large load of white towels, (so sayeth the label). I also soak anything I am sanitizing overnight in the bleach solution, then rinse thoroughly and allow to air dry. Air drying kills nearly as many bacteria as bleach.

[silken]

I've always heard it was 1/10 part bleach. I just use the regular bleach I buy in the laundry dept. and add 1/10th (1.6 cups) or a bit more to a gallon of water. Now you can get more concentrated bleach as well, so guess I would just use the same or a bit less bleach in that case.

[lotis146]

Interesting...I've not been measuring to be honest. I have plastic planting pots that I soak plants in as well as old pots. I just pour in a couple of splashes of bleach and fill the pot with water. I've always understood a little bleach goes a long way but I'm not the most experienced Orchid grower.

But I personally would find it really hard to believe that a full solution of bleach or even 2% is necessary. Just think about the kind of things you do use full bleach for...but if anyone has different evidence I too would be interested to hear it.

[Laserbeak]

I usually just run them through the dishwasher. on "Soak & Scrub" and "High Temperature Wash."

If the plant in it before was known to have a disease, then I'd throw it away unless I really liked the pot or it was valuable, in which case I'd pressure cook it at 15 lbs. pressure for at least 1 1/2 hours.

There are known pathogens that can survive bleach, but nothing except perhaps prions can survive proper pressure cooking. And since plants don't have nervous systems or brains, prions (which cause mad cow disease) aren't an issue.