Seaweed as soil amendment

– Posted in: Mailbag
7 comments

Mary emailed me and asked:

I understand that using seaweed in your garden helps the build the soil. How much seaweed do you use? And does the bromine in the seaweed help get rid of the bugs in turnip?

Now, the seashore is probably a four hour trip from here and I know nothing about seaweed. If any of you readers can answer this question, please do so in the comments. Mary and I would both appreciate it.

About the Author

Kathy Purdy is a colchicum evangelist, converting unsuspecting gardeners into colchicophiles. She would be delighted to speak to your group about colchicums or other gardening topics. Kathy’s been writing since 4th grade, gardening since high school, and blogging since 2002.

In the spring, at the end of the day, you should smell like dirt.

~Margaret Atwood in

7 Comments… add one

Nicole December 20, 2007, 6:45 am

I use it as mulch for my large plants in pots and it works great.Some people warned me the salt might kill the plants, but it has never happened to me. Also mixed in the compost for tomatoes

Sven Whitson December 18, 2007, 7:13 pm

While it can be a great soil ammendment, you will want to make sure that what you will have planted in that ammended soil can handle salt. For instance in the bamboo growing community, seaweed is HIGHLY frowned upon, as the salt it adds to the soil will kill or severely hamper the bamboo’s growth, as it is sensitive to salt.

Kathy Purdy December 4, 2007, 7:18 am

Thank you to everyone who shared their experiences.

Denise December 2, 2007, 2:11 pm

I live near a lake where they have to harvest the seeweed to prevent problems. Seeweed is excellent to add to a compost bin. It is so rich in nutrients. Denise

Giddy November 30, 2007, 4:47 pm

We live right on the coast of Maine and every year I scoop up loads of seaweed to mulch my garden in winter. In summer, I fill a plastic tote with the stuff, fill with water to cover, let steep and water all my potted plants. They thrive on this stuff. I highly recommend it.

Linda MacPhee-Cobb November 29, 2007, 7:14 pm

I used it. You’re neighbors will love you. It is best placed in the garden up north in the winter.

Also yours and the neighbors cats will go roll in it and come home stinky. It’s a great way to discourage your neighbors from letting their cats loose.

I don’t know that it made a huge difference in plant growth. I’ve found worm castings and fish emulsion to be better fertilizers if you want natural ones.

( Same warnings apply for fish emulsion . )

Tina November 29, 2007, 10:20 am

Anne did a nice post about seaweed back in October-
http://annesgarden.wordpress.com/2007/10/28/seaweed-in-the-garden/

Everything I’ve read about using it pretty much says to load it on, you can’t overdo it and it increases the disease resistance in most plants as well as helping to keep some bugs away.

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