Seaweed Pops or Agar Plugs


Here’s an upsetting problem I’ve been trying to overcome for the last year.  How can we ship seagrasses without sending enormous vats of soil but also ensuring roots arent damaged in transit and microbes hitch along for the ride? 

I think I may have worked out an answer: agarose plugs!  You may have seen a product called Crystal Soil in hydroponics shops or garden centers in recent years.  Its based off a product known as agar (or agarose), the gel-inducing part of vegan jello.  Its the same base used to make petri plates and is a workhorse in the biotechnology and pharmaceutical industries.  Truly a miraculous little product, courtesy of one of my favorite things: seaweed!

In essence what I’ve been working on is a way to root seagrasses into a medium that meets certain criteria:

  • Wont erode in saltwater
  • Can carry nutrients to the plant if embedded in the medium
  • Is easy for the roots to grow through
  • Wont introduce excessive amounts of nutrients into new systems

So what exactly have I been doing?  Well, I’ve been making agar plugs by following the directions on the bottle.  Agar is already widely used in plant cell culturing techniques, so it wasnt exactly a revolutionary choice.  I’ve even used vegan jello to make these preps.  I pour the ready agar/jello into small molds and place these in rows with a growing seagrass rhizome strapped to the top.  With luck the plant roots easily into place (the majority of the time). 

After a few weeks I cut a bar of the agar with the seagrass roots intact and, voila, instant seagrass transplant!  I’d love to try this out with seagrass seeds but I’ve never been lucky enough to come across any of it here in Florida.

The really excellent thing about these jello plugs is that, if fertilizers are added to the water when the gel is being prepared, it is effectively sealed into the pores of the gel and becomes available to the plant roots as they grow into the medium.  Instant nutrition for the plants.  I’ve also experimented with adding seagrass mulm to the gel as a suspension when the gel is prepared.  That approach also seems to work very well. 

I cant decide for certain if the microbes are being kept intact through this process, or if these plugs will indeed ship better in the future, but I’m getting dangerously close to being ready to find out yes or no on both of these concerns. 

What I have come across lately, and a lot of it, is the protected Johnson’s seagrass (Halophila johnsonii) just off the Lagoon.   These plants are small and delicate and are easily thrashed by even the slightest waves in the Lagoon within a day or two.  I’ve never seen so many plantlets uprooted so I suspect the spot I visited must have a nearby bed of the endemic little plant.  It is a cute specimen though, and I’m sorry that I can experiment with it in my tanks.  Think of a small paddle grass (Halophila decipiens) or a two-bladed stargrass (Halophila engelmannii).