I was checking into using "water crystals" in my organic garden because being
in Zone 9, we need to retain as much moisture as possible in the soil.
A British company suggested that I use "Seaweed meal", i.e. ground up seaweed,
as this would help retain water in the soil. I see this is being used a lot on
England, but can only find liquid seaweed or kelp here.
Does anyone here have any experience with this stuff? Where can I get some in
the US, prefereably Los Angeles area.
The idea was that the seaweed meal somehow had better water retention
capabilities than home grown compost. In So Cal, we sometimes have no rain
between February and October and little in those months. We need all the help
we can get to keep water in the soil so be able to grow plants without enormous
Articles do indicate that seaweed or kelp meal (ground Ascophyllum nodosum)
acts as a natural humectant in addition to having other plant benefits such
as assorted trace elements and nutrient content, but it is unclear as to the
degree of water retention it can provide solely as opposed to inclusion of
other organic matter, such as compost. I'd venture to guess that one would
need a considerable amount to achieve the same moisture retention that
compost or other quality organic matter does and at a far less cost.
Gathering and drying the kelp or seaweed yourself would certainly
reduce/eliminate the cost factor and you could get a significant quantity,
but I'd still consider adding it to your compost to maxmize its usage.
pam - gardengal
Whitney Farms is a West Coast producer of organic soil amendments and
fertilizers and they carry a kelp meal (not a liquid product). The link will
give you a whole slew of California locations that carry their products.
I would say that Travis is on the right track, though. Additions of good
compost or other quality organic matter will provide as much, if not more,
water retention capacity to soils as would kelp or seaweed meal and is a lot
cheaper and easier to use in quantity. Doesn't have to be your own if you
don't have it - any good quality bagged or commercial compost will work just
You could also take a winter time drive to the beach for a little seaweed
harvest of your own. It tends to be very plentiful in winter. Just gather it
up, rinse it off well and hang it to dry. Once dry, you can grind or
otherwise chop it up and include it with your other soil amendments. I find
southern California beaches to be very pleasant at this time of year :-)
pam - gardengal
In many areas of southern California, the water and soils already
contain excessive salts. I would be very concerned about the salt
content of seaweed.
A good mulch of leaves will help your soil to remain cool and moist
in the summer. Eventually, they break down and make a good
Another way to ensure proper moisture retention is to amend the
soil with a 50-50 mix of peat moss and washed plaster sand, both of
which should be suitable for an organic garden. If your soil is
already sandy, reduce the plaster sand and increase the peat. See
my <http://www.rossde.com/garden/garden_potting_mix.html . For my
recipe, you can likely find organic substitutes for the nutrients
that you do not consider organic. Note that there are indeed
natural sources of sulfur, gypsum, and Epsom salts, which (although
inorganic) are used by organic gardeners.
David E. Ross
Climate: California Mediterranean
In Alaska, we go down to the beach after really good storms, gather up
all the seaweed we can carry, then lay in on our garden beds (without
rinsing the salt off it) and let it rot. Seaweed has all of the trace
minerals plus N, P & K in it.
Folks in SE Alaska, who don't have topsoil, gather seaweed, lay it on
the bedrock in their yard and plant seed spuds in it. They get
tremendous crops of potatoes.
Jan, in Alaska
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