Beautiful Native Plants

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Monday, February 22, 2016

Managing a natural pond

Water spangles (Salvinia minima), an invasive floating fern.

Trouble in paradise

Previously, I wrote about how much we have enjoyed our front pond in The joys of a Florida pond, but in 2011 the whole surface of the pond had become totally covered by a noxious invasive with a cute name—water spangles (Salvinia minima). It had probably come in as a hitchhiker on one of our beloved birds or traveling turtles, and from there, it went wild.

My husband and I scooped out cartloads of it by dragging a 8′ piece of plastic mesh between us as we walked across the pond and we scooped up more with hard plastic leaf rakes. I used it in the compost pile and as a mulch, but each time we cleared out a batch, new, bright-green plants filled in the spaces in a matter of days no matter how large a gap we created.

An invasive floating fern had completely covered the surface of the pond.

A beautiful scarlet rosemallow (Hibiscus coccineus) lights up the edge of the pond. As you can see in this 2009 photo, there is some Salvinia around the edges of the pond, but it was knocked back by a cold winter.

No matter how much Salvinia we pulled out of the pond, more grew back to recover
the whole surface of the pond.

Before 2011, the Salvinia was not too much of a problem, but from this year forward, it got worse no matter how much physical removal we did. We thought a hard winter would eventually take care of it, but after two years it was still covering everything. I hated the thought of using herbicide, but there was no other solution. Bummer!

The solution…

I called the contractor who had been hired to get rid of hydrilla (Hydrilla vercillata) in the big lakes in the neighborhood. He quoted us a price for treatment with Fluridone, an herbicide especially formulated for aquatic habitats. (Round-up and many other terrestrial herbicides are not effective on aquatic plants and kill the fish, turtles, and other aquatic wildlife.)

Removing the spatterdocks before the
herbicide was applied.

He told us what other plants in addition to the salvinia the herbicide would kill. It would NOT affect the ferns, the irises (Iris hexagona), the rushes (Juncus effusus), hibiscus (Hibiscus coccineus), or the lizardtails (Saururus cernuus), but it WOULD kill the native spatterdock (Nuphar advena), a large  yellow waterlily that had also covered too much of the pond.

The spatterdock would have added a huge volume of muck in the bottom had we left it in place. So before the treatment, we removed more than half of it from our side of the pond. This was a big job because of its huge rhizomes, but it does float, so after pulling it up we could herd the pulled plants to the side of the pond.

Our pond was such a small job for the contractor that he never got back to us. So after waiting 20 days, we cancelled the contract and bought the Fluridone ourselves–it was quite expensive about $140 for 8 ounces, but we’d need only half of that for one treatment and our neighbors paid for half of it since they were getting ready to put their house on the market. It would be easier to sell with a clear pond.

After reading everything he could find on this herbicide, including the label, my husband put his kayak into the pond and was ready for action. He filled the 2-ml syringe ten times and injected the doses in equally spaced places just under the surface of the water around the pond. After the application, he paddled large figure 8s all over the pond to better distribute the herbicide. It would take 45 days to begin to work.
My husband injected the Fluridone with a syringe in 10 different spots in the pond.

After inserting the herbicide, he then  paddled figure 8s across the pond to better distribute the fluid. You can see that there are only a few spadderdocks left in our side of the pond at that point.

A few weeks after the treatment, we removed the rest of the spatterdock. It was a big job, but it would be best for the pond. This pile did not go into the compost pile, it still had herbicide residue on the plants. The neighbor's side of the pond will have to fend for itself. To lighten the nutrient load, we removed some of the trees and shrubs leaning over the pond. This black willow will grow back, but for now those leaves won’t fall into the water.


In nature, eutrophication is a part of the normal aging process of many lakes and ponds where they slowly fill up with decaying matter until they become swampy meadows or bogs. Ponds that are naturally fed rich nutrients from a stream or river or some other source are described as “eutrophic,” meaning they are nutrient-rich and therefore abundant in plant and animal life. In urban/suburban locations, this process is greatly sped up if people’s lawn fertilizers and debris are also carried into the ponds and lakes. Often the result of this overly nutrient-rich environment is an ugly algal slime and dead zones where fish die in the oxygen-depleted environment.

At the present time, there are no artificial nutrients washing into our pond from the surface, but there is a deep layer of muck (knee-deep in the center). Before we bought the house 10 years ago, the previous owners had hired someone to kill the pond vegetation, which probably accounts for much of the muck layer. In addition to removing the spatterdocks, we worked to reduce the amount of leaf-fall by trimming back some of the trees and shrubs at the shoreline. There is still plenty of shade, but maybe now with fewer overhanging branches, the pond muck build up will slow down some.

Now, pond life goes on…

The spatterdock on the neighbor’s side of the pond has now completely disappeared into the water and we are enjoying the salvinia-free pond life again. We are hoping not to have to use the other half of the Fluridone for many years.

6 weeks after the treatment, the pond is clear enough to enjoy the reflections again.We love our snakes! This non-venomous reptile will feed on dead or live animals such as fish and frogs and it plays an important role in the pond’s ecosystem. They usually stay in the water, but on this day, it’s basking on the pond-side log instead of the turtles.
There’s life in the pond-side snag. Zebra longwing caterpillars are feasting on the passionvine there.
Life in the red bay snag: The beautiful red bay trees (Persea borbonia) around here were hit with the laurel wilt fungus. (For more information on red bays, see my article, Red Bay Trees are Dying.) All that’s left of one of our red bays is this pond-side snag, but it’s covered with several species of vines including one of the Florida native passionvines (Passiflora incarnata), which is now covered with zebra longwing butterfly larvae. (See my post Teeming with Zebras.)

The native blue mist flowers attract many
pollinators and are relatives of the
ageratums, the garden plant.

Have you missed the blue mist flower (Conoclinium coelestinum), an eastern US & Canadian native? It has volunteered on the pond shoreline and the front meadow for years. The pollinators love it and so do I.

So I hope you are enjoying the life in and around your pond, but if you don’t have one yet, maybe it’s time to add one to your landscape to create a better habitat for myriad wildlife species that are so much fun to watch.

Be sure to read part 1 of this adventure: The joys of a Florida pond.

© Ginny Stibolt