Yardenman said:Well, I feel better giving the pots and cell packs a clean start every year. Mostly thinking that it can't HURT to do it. And it gets me going for the new season.
Me, too. I think it's better to clean well
before putting away for the winter so fewer microbes have that long to turn into spores. But that depends on how busy I am in fall!
Mostly I have trays of small plastic cells or 4" pots, and they are only in use for a few weeks or one season. So they don't get crusty or baked-on.
It seems easy to me to rack them all up on "webbing trays" and stack them up so the runoff from one layer of pots washes the layers underneath. If it's the rainy season, I leave them out for while so rain will soften and pre-rinse them.
Then I use a hose-end sprayer on "hard spray" or "mist" to blast all soil or mix out of the top layer, and soften/rinse the layers of trays underneath. I use a webbing tray on top of the top layer so the hose spray doesn't blow them all around the yard.
When the top layer is "clean enough", I set it aside to dry and start spraying the next layer down. That's enough to get most of them visibly clean. Any that aren't visibly clean I pull out to soak and scrub individually.
This hose-end-sprayer pre-wash keeps the dishwasher from filling up with soil & mix.
One year I set up my dishwasher to run one full cycle, but I kept interrupting it to add detergent and replace the current load of clean-ish plastic trays and pots with the next load. That way, ONE dishwasher cycle let me give MANY pots and trays vigorous spraying with caustic dishwasher detergent. They continue soaking in the caustic detergent film until all are washed. Then I take them outside to rinse in one big stack.
But bleach is better for killing microbes.
I think that mere cleaning removes 99% or 99.9% of possible plant pathogens.
But what is 0.1% of a serious soil infection? It's still a serious soil infection!
So bleach (sodium hypochlorite - CHLORINE bleach) is needed to prevent ONE infected pot from infecting everything touched by water that passes through it (like every cell or pot in the same tray plus anything that any re-used potting mix contacts).
Maybe those who
don't need bleach every year have almost no soil infections to worry about anyway.
But maybe the people who say "I usually can't grow plant X because of plant disease Y" have more need for bleach than they realize.
On the other hand, maybe someone with
lots of soil diseases locally doesn't get much benefit, because no matter how well she cleans her pots, rain and dust re-infect every pot and seedling shortly after it goes outdoors.
I don't know. But I always clean well, and usually also soak in chlorine bleach diluted 1:10.
