Be very very careful with caustic soda/sodium hydroxide. It is very corrosive to skin. Avoid is best advice.
It you think you can handle it, dissolve it carefully. Always add the NaOH slowly to water, with constant stirring (but no splashing). It will heat up. NEVER add water to the dry caustic soda !!!
location: Surrey Hills, England, ex-woodland acidic sand. "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
Concentrated Washing Soda is dangerous also, follow the instruction on the pack. I spray path weeds with neat malt vinegar (esp during lockdown) it works quickly on top growth. I have trialled this on some Nostoc, and will report. Boiling water also works.
location: Surrey Hills, England, ex-woodland acidic sand. "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
Do not use Caustic soda (Sodium hydroxide) for this purpose!
It is Washing Soda (Sodium Carbonate) that is being recommended, a much, much less hazardous substance, but still needs to be used with care and by following the method shown, which has been summarized on this page:
Having searched widely, I found with an answer: Thin Bleach. It worked on my limestone chippings roof back in the spring. Where I treated all is well, but I have just spotted this in an area that I hadn't treated:
Thin bleach, for some reason, is not easily available at the moment. Thick bleach doesn't spray well. I bought some 15% NaOCl on the internet and diluted this to 5% before spraying. It worked well.
As I said earlier on this thread, I have done a trial using 5% malt vinegar, it worked. I will treat this patch with vinegar as I have that ready for use in a spray bottle. If that doesn't work I will try washing soda (NaHCO3).
After several years with no answer, I now have several.
Be very careful with chemicals
Don'r worry about me, I'm a Chemist.
location: Surrey Hills, England, ex-woodland acidic sand. "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
Interesting @GardenerSuze I've also yet to see anything resembling slime on gravel areas - or anywhere else come to that. I have a few gravel areas but the only thing they seem to attract are common weed seedlings which I just pull out when I think about it. I don't have @Bede 's chemical expertise but I wonder whether the more you try to eliminate some life forms by chemical or non natural means, the more you invite other problems ? Just a thought and no stats to back it up - simply my own gardening experience over several decades.
@philippasmith2 I have always thought that the more you use chemicals in a garden the more you have to continue to do so it becomes a vicious circle. The natural balance of the garden is damaged.
I have worked as a Gardener for 24 years. My latest garden is a new build garden on heavy clay.
BTW, I never touched my roof until the Nostoc arrived. So the roof was completely organic.
A garden is an artificial environment, everything has been changed. In fact every material you add is a chemical. Some with know effects, many unknown compostion anf effect..
How will you react when you get it?
How do you clean up after your cat?
location: Surrey Hills, England, ex-woodland acidic sand. "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
Posts
It you think you can handle it, dissolve it carefully. Always add the NaOH slowly to water, with constant stirring (but no splashing). It will heat up.
NEVER add water to the dry caustic soda !!!
"Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
Concentrated Washing Soda is dangerous also, follow the instruction on the pack.
I spray path weeds with neat malt vinegar (esp during lockdown) it works quickly on top growth. I have trialled this on some Nostoc, and will report.
Boiling water also works.
"Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
Thin bleach, for some reason, is not easily available at the moment. Thick bleach doesn't spray well. I bought some 15% NaOCl on the internet and diluted this to 5% before spraying. It worked well.
As I said earlier on this thread, I have done a trial using 5% malt vinegar, it worked. I will treat this patch with vinegar as I have that ready for use in a spray bottle. If that doesn't work I will try washing soda (NaHCO3).
After several years with no answer, I now have several.
Be very careful with chemicals
Don'r worry about me, I'm a Chemist.
"Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
I have a few gravel areas but the only thing they seem to attract are common weed seedlings which I just pull out when I think about it.
I don't have @Bede 's chemical expertise but I wonder whether the more you try to eliminate some life forms by chemical or non natural means, the more you invite other problems ?
Just a thought and no stats to back it up - simply my own gardening experience over several decades.
A garden is an artificial environment, everything has been changed. In fact every material you add is a chemical. Some with know effects, many unknown compostion anf effect..
How will you react when you get it?
How do you clean up after your cat?
"Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
I am not a Chemist but an educated Gardener who takes a totally different approach.
! am afraid that tgis post has forced me into the upper 900s posts. I must resist becoming one of those saddos who tops 1000.
A garden is an artiificial envronment. You don't get them in the wild.
"Have nothing in your garden that you don't know to be useful, or believe to be beautiful."