Kitchen Garden Forum

I would be grateful for some advice on caustic soda. We believe that one of our new plotholders plans to put caustic soda on half of his allotment then cover it over with plastic for a year. We have never come across this as a way of killing off weeds. Is this safe to do, bearing in mind the plot is near a stream and there are children on site? Also, will it be safe to grow plants in the soil after a year?

Any advice gratefully received.

Thanks,

Susie Sweetpea

Hi Susie and welcome to the forum

Your fellow plotholder sounds dangerous and not much of a gardener

I must admit that I have never gardened in chemical warfare mode. For some authoritative information on caustic soda, its use and danger, see the Dow Chemicals site.

If your plotholder starts like this, what should you expect in the future?

Hello Susie
I can't see the point of using caustic soda then covering with plastic for a year. The plastic covering alone would do the job well enough. It sounds dangerous but in fact if he uses it a pretty dilution solution there probably isn't a problem. After all some people use salt, sodium bicarb. or sodium chlorate on their gardens though these are not strong alkalis like caustic soda. He's more likely to harm himself mixing this stuff! Spraying caustic soda solution could lead to problems though.

You don't say how your site is run but, if possible, someone from your committee should have a polite word with this chap to find out exactly what he intends to do and offer some guidance. In the longer term I suppose your site should have some policy on the use of chemicals. I know these policy sort of documents are a real pain in the butt (they seem to be everywhere these days) but at least it would let everyone know exactly what can and can't be done. More importantly it gives you the strength to take action against a plotholder if they step over the line. In all these sort of situations do keep a written record of who said what and when in case there is more trouble.

John

Hi John and Alan

Many thanks for your advice re caustic soda. I will pass on your comments to our committee to discuss at their meeting tonight. Like John, I would have gone down the plastic (minus caustic soda) route.

Kind regards,

Susie

Are you sure he hasn't got the wrong end of the stick, and really means sodium chlorate, which would be more conventional - though not necessarily the best of ideas.

But if he does mean Sodium Chlorate then he is still a fool.
It's a path weedkiller of the persistent kind and it leaches.

But is this all third or fourth hand, "send three and fourpence, we're going to a dance" type stuff?
Or did you hear it straight from the person concerned?

Peter - I know what you mean, we had it second hand so went back to check with the person who heard it first hand and yes he does mean caustic soda!

Hi Elaine,
Caustic Soda could render the plot unusable for ever.
If you note in the Dow website. If spilt on soil the soil must be removed.
What you do with it is a little unclear.
I dread to think what the PH would be. Certainly off any PH testing kit.
This person must be prevented at all costs.
JB.

I find this topic interesting. There are plenty of natural ways to kill weeds yet typical home owners still turn to poison. Caustic Soda is often used in water treatment to treat PH conditions. Small amounts are injected directly into drinking water. Its sounds like it may be safer for the environment than Round-up since some people drink caustic soda everyday. It would without a doubt kill weeds.
I chose to save a few bucks and be environmentally friendly and get down on my knees and just pull the unwanted pesky plants. Does that make a difference when I'm chugging gasoline to get to work and back everyday? Not much...I'm just the typical human cancer going along with the herd, typing away on my radio-active plastic know it all machine that will look great in a landfill someday. Maybe Ill just drop it on the ground in the middle of some shady section of New Jersey where trash cans don't exist and people are the purest form of scum. The city workers once a week will make sure my trash gets blown via leaf blower into the storm drain so they dont have to trip over it anymore. Then it will end up in the ocean like everything else. Ever wonder?... if a Volcano erupts 1,000 years from now underneath the worlds largest landfill what would happen? I can go on forever, so I'm getting a beer and working outside. You don't like me? Good. Stop wasting your time.

I use caustic soda as a very effective weed killer on spaces that I do not wish to plant.
It has the advantages of being cheap and safe once neutralised by air. Application is by sprinkling grains of solid soda over the area to be cleared. Then spray warm or hot water over it until dissolved. The concentrated solution will then percolate down through the soil and permanently inactivate all seeds. This prevents seed growth even when re-exposed to light and air.
Subsequent rainfall will dilute the solution and absorption of carbon dioxide will neutralise it to harmless washing soda.
Do use gloves and eye protection when handling the solid caustic soda.

I will endorse the comments above, I can not imagine why anyone would treat the soil thus. (I take the point that one might use soda on a path).

I would also add, why take on a plot only to ignore it for a year? Do you really want plots to wholly disappear under plastic? It seems a sure way for someone to find they use their gardening time elsewhere or to loose interest or forget they took the plot on. Many of us might set a portion aside for season or a couple of months but the whole area for a whole year? Are there no plotholder conditions about cultivating the plot?

I can't believe there is a gardener out there with so much patience to wait a year & I believe in all the rules there is something in there about growing something. Surely taking on a plot & not working it is in breech of the contract? Sure you cover off season but the point is to grow crops.

Wonder how big the waiting list is there? Because we are beginning of season & change of council they are just sorting out how many haven't renewed (lots) but we just have 14 waiting (who'd believe that 8+ yrs ago when it was over 100). Lot's of those 14 wander around the site frequently just checking the plots & challenging the committee, who in turn challenge the owner of said plot. I hope more sign up as we are still in danger - doing my bit & have encouraged 2 to get their names on the waiting list!

We was on the waiting list over 6 years we have had the plot around 9 years I believe now there is no list but our allotment has been extended

It seems I was lucky in 2006, as I waited just a year to get my first, half-plot. I was even more fortunate when the other half of the same plot was not used for the year and I consolidated it back to a full size after a very short time. It still surprises me that I have had 13 years of gardening (it would surprise my late mother even more as I showed little interest as a child)