|Seaweed is an almost complete plant food - Irish farmers grew potatoes without soil purely by layering seaweed onto sand and rock.|
What type of seaweed is best? All types contain fabulous nutrients and plant hormones, in forms readily available for plants to use. Fine, soft types like sea lettuce are easier to spread, and break down rapidly while at the other extreme, tough, leathery kelp might take months to break down (slow-release fertilizer).
To rinse or not to rinse? I never rinse seaweed, without any ill effects, but on the other hand it won’t do any harm to hose it off if you feel so inclined.
Where do I get it? Seaweed mostly grows on rocks, so Kāpiti’s sandy beaches aren’t the best source. But it does wash up after southerly storms. Further afield, Plimmerton and Lyall Bay are good collecting grounds - throw a sack in the car boot if you are heading that way.
Holding water: The gelatinous quality of seaweed makes it a great water-reatainer (eg for container grown plants- bury some towards the bottom of the pot.)
Jumping with life: A pile of seaweed left for a day or so will soon be teeming with worms and a huge variety of other microbes and macrobes. Perfect for your compost or soil as all those creatures help break down nutrients into forms plants can use.
Check local signs for restricted areas, and don’t collect seaweed from within marine reserves. It might look like it’s just lying around on the beach, but it may be playing an important role in the marine ecosystem.
What about that mulch stuff that washes up? The fine mixture of twigs, leaves etc washed downstream after heavy rains ending up on the beach can also be laid directly on the garden as mulch. Or mix it with grass clippings for great compost.
The Council Green Gardener, Hannah Zwartz, offers sustainable and waterwise gardening advice to local residents, community groups and schools.
Community Visits and workshops are free. Get together five friends or neighbours and invite the Green Gardener round.
Contact Hannah through the Council Service Desk 296 4700 or at firstname.lastname@example.org