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Using raw seaweed on the garden

I know a beach where there is a lot of washed-up plant material mixed with broken-down seaweed. It looks like a fine mulch and I used to get bags of it and spread it on the garden. Now I have been told that the sea salt in this mulch is bad for the soil and detrimental to plant growth. Is this true?


Yes, you could end up with a build-up of salts in your garden if you use this washed-up plant material. You may find sensitive plants fail to thrive.

If using seaweed for the garden as a mulch, soak it in fresh water overnight first to wash out the salt.

UnitecAdvice by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor of Resource Management.

Reproduced with permission from NZOOM Home and Garden content,
from the previous website of  TVNZ News

The views expressed here are not necessarily those of the RNZIH

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Last updated: June 27, 2005