How to Make THE Floating Island

goodkarma_(5b)April 9, 2009

Floating Islands are very expspensive. The size I wanted was $189 at the Garden Center. So I made a pretty good replica - the biggest difference is that mine are blue and the Islands are black. You can paint yours if it matters to you. I used a little green spray paing to cover the great stuff that showed.

The materials: Washable furnace filter from Home Depot, Small Cable Ties and Great Stuff Window Foam (Not the Gaps and Crack filler- it is not as good). Spray paint - color green or black.

Take TWO furnace filters ($5 each) and use the cable ties to hem them together. Add two in the middle some where as well. Next cut out circles where you want the plants to go. Then use the Great Stuff and fill it in avoiding the holes. I finished Islands with one can.

Take the spray paint and hit the great stuff that shows thru. I used green. Next add plants and an anchor to keep it from going in your skimmer. I used Savio Springflow, but fishing line would work too. I want my fish to avoid the line so I like that they can see it.



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ok I'm terrible at directions.. is the foam to fill in around the holes to make something like a pot? do you add dirt? the roots don't flow thru to the water on other side right?..

    Bookmark   April 10, 2009 at 12:41AM
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The foam is what makes the island float. You sandwich it in between the layers of the filter. Floating planters usually don't use dirt because it ends up in the pond eventually. I was going to use coconut fiber to secure the plant roots but they all fit in nicely and I didn't need too.

I am thinking of sprinkling some Allysum seeds on the tops of the planter.


    Bookmark   April 10, 2009 at 9:06AM
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Update- if you check out the thread listed below you will see examples of how these planter will support enormous plant growth. So I would recommend that you add a little more of the window foam so that your plants do not sink if they get too top heavy. I have one planter I put watercress in and it did so well and the plants got so heavy that it is now partially underwater. This is OK for water celery but would cause crown rot in impatients.


Here is a link that might be useful: Jenny's floating planter thread

    Bookmark   July 29, 2009 at 11:36AM
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You might want to put an airstone under the floating island. Below is a link to an article on floating islands. The article starts on page 8 of the pdf. The second part of the article is in the July issue of the same newsletter.

Here is a link that might be useful: Article on floating island

    Bookmark   July 29, 2009 at 3:39PM
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Cool. I made one from a piece of hard foam with holes for plants too. I anchored it with an old dumbell and rope.

I tried a little coco fiber in the holes as plant support, but it seemed to get a little rotten.

    Bookmark   July 29, 2009 at 6:05PM
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Thanks Mike. I enjoyed the article and found it very interesting. Airstones sounds like a great idea to increase the filtering capacity of these type of floating islands. I am intrigued by the idea and will have to try it.


    Bookmark   July 29, 2009 at 9:12PM
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I have to apologize for my stupidity but I am stumped at the size of the holes in the filter. At first I thought you put the roots in the holes but then I wondered if you put the plants in flower pots and set them in the holes. Sorry that I'm so dense. You make it sound so simple, I went to HD, got filters although they did not have the ones that you are showing. The ones I got were pretty rough in texture but I used them anyway. But, because I could not figure out about the size of holes I just poked the roots through very small holes I poked in the filter. I have no idea if this is going to work, but I'll see. The filter you show looks to be very soft material. But my main concern is what you did with the holes you cut in there. I guess I would have a better idea had I seen one in a garden shop somewhere but I have yet to run into them. Thanks so much for your help, I am DETERMINED to have one come out a gorgeous as yours. (hopefully) lol. BT

    Bookmark   May 22, 2010 at 10:15AM
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catherinet(5 IN)

Hi BT,
You don't use any pot. You just set the plants in the holes. The roots get their nutrients straight from the water.
Don't forget the window foam between the 2 filters, or it will sink. I'm not sure how vital it is to get the kind of filters that Lisa suggested. Good luck with yours!

    Bookmark   May 22, 2010 at 10:33AM
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Thanks, cath. Honestly I am trying!! Well, so far, however wrong I did it, they don't seem to be dying, and I did use the foam. THAT part is working. I can only hope the scratchy filter doesn't do them harm plus the small holes I forced them through. I just didn't know how the roots would stay in those holes without the pots. Told you I was kinda dumb at this. LOL thanks again.

    Bookmark   May 22, 2010 at 1:13PM
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catherinet(5 IN)

Don't worry about it brownthumbia.......there's a ton of stuff I have trouble getting too! Soon you'll be an expert on floating islands!
I think the roots will find their way out of the mesh and just hang in the water....which is fine......unless you have fish that might nibble on them.
What kind of plants did you use?

    Bookmark   May 22, 2010 at 2:24PM
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Cath, thanks a lot. I only put impatiens on the filter...went out and double checked them today and, I do believe they are looking pretty good. Yeah!!!! Boy, if this works I'm buying a truckload of filters and fill every one. LOL I do have some Koi in the pond but hopefully they won't harm them too much. If I could get mine just half as nice as the pics I've seen I will be one happy ponder. again thanks. BT

    Bookmark   May 22, 2010 at 9:26PM
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catherinet(5 IN)

Glad to hear your impatiens are looking good!

My ponds are very small. I just bought a small floating ring at Lowe's a couple weeks ago. When I was going through the check-out, the woman said "that looks just like the one's they have at the dollar store". I checked out the dollar store, and they sell little round green Styrofoam rings for flowers. I bought one for $1 and set a pot of stargrass in there, and it works just as well as the $6 one from Lowe's!
Good luck with your filters!

    Bookmark   May 22, 2010 at 10:15PM
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beck_wi(z5 WI)

I kinda made one of these. I took some black felt I had a bunch of and sewed it into a unstuffed pillow ( a top piece and a bottom) then before I turned it right side out, I put small pieces of foam in.
I closed up the seam, cut a few holes, pushed the chunks of foam out of the way, and put 3 impatients in it.
Total cost $0--- except the plants.
Mine is smaller, but I have a small pond.

I tried to make another one with a ring of foam.... it kind of came out looking like a little boat. I'm not as happy with that one so hopefully the plants take over and cover it.

I found my foam chunks at a car dealership I clean. These chunks are put on the cars with double sided tape to keep them from getting scratched. The first time I found one I was like "oooooh, I'm not throwing this away" lol
I think you could use those foam tubes they sell for insulating water pipes the same way.
The only drawback to my foam chunks is they are bright blue--- but that's better to my eye than the bright red pool noodle I used a few years back.

    Bookmark   May 24, 2010 at 12:32AM
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Simply amazing. Well done.

    Bookmark   May 24, 2010 at 7:49PM
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Lisa. your floating islands are a perfect marriage of creativity & innovation. Necessity is the mother of invention, eh? Alas, they are much too big for my humble lil watering hole...someday!!!

In the meantime, your ingenuity encouraged me to experiment. Last year, a plate-sized piece of a/c filter & some pipe insulation became a frog island. I sprigged it with some sweet potato vine & seeded it with watercress and my froggies were thrilled! Late night visits to the pond confirm their glee, lol.

Encouraged & inspired, I drilled holes in one of those foam garden-kneeling pads & sprigged it w/watercress. Turned out beautifully. Ha. Can't hold a candle to your floating beauties but it works for itty bitty watering holes and knocks the socks off my non-ponding friends & family.

THAT along with a couple of florist rings from Dollar Tree w/pots of impatiens dropped in has em all thinkin' I'm an expert ponder ROFLOL! 'Course nothing could be further from the truth, BUT I'm having FUN!

And in the big scheme of things....that's really all that matters.

All that to say, thanks for the inspiration.


    Bookmark   May 24, 2010 at 9:14PM
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Hot topic. On page 3, Finally - posting some pix, shows a couple of floating islands I made using both the furnace filter and a recessed lighting grate for lights in suspended ceiling, both being floated by great stuff foam.

Before the foam hardened I set pea gravel into the foam, tried also using sand, some stuck, most didn't

I made holes for pots, but split the sides/bottom of the pots (the cheap plastic that you get when you buy the plants) for water flow and roots, the plant ring medium is bedding which helps hold the plants and also keeps the Jobe plant spike in place. I usually place some pea gravel on top of the pot for stability and decoration. In the last island I made, I put some slots and have planted(stuck) parret's feather into the slot, also trying some other plants. So far so good!

I also used an oil change pan with hot water pipe insullators for floatation, used wire ties to secure to the oil change pan. The insullators become somwhat waterlogged over time.

I had dragon tails in one and had to secure a quart sized plastic food container with a few river rocks to keep it vertical when the plants got about 3' tall.

    Bookmark   May 24, 2010 at 9:40PM
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OK, it's been some time since these posts were made. I'm curious as to how long these filter islands last. I have the small size 'real' pond island (the expensive kind), I think mine is at least 4 years old now, entering it's 5th season of use. We just went out to look at it, before I started this post, and it is showing some disintegration but is floating nicely and holding up the mint and chives just fine.

    Bookmark   May 5, 2012 at 2:37PM
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I'm not sure I would use a spray paint on anything I put into my pond. I'm actually not even sure about using an AC filter as island material as it might be made of something harmful to my fishies.

Here is a link that might be useful: How To Build A Floating Island

    Bookmark   August 11, 2012 at 5:01PM
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Shalom - used the A/C filtrer, worked okay, but I get small bits of the filter material that break off- I guess it could get stuck in a gill. Made only one filter out of A/c and it's been in service 3 years, not side effects. Then I switched to the light grid and great stuff foam, have 2 islands that have been in the pond 2 years, no side effects.


    Bookmark   August 11, 2012 at 8:47PM
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steiconi(12a-Big Island, HI)

Based on this thread, I just created my first floating water lily pot! I used a plasticized feed bag, turned a cuff down around the top, and threaded about 3/4 of a pool noodle into the cuff. Then I used a big sewing needle and fishing line to whipstitch around the cuff and noodle.

Then I added cheap unscented kitty litter (it's bentonite!), and popped it into my tilapia tank (so I wouldn't have to lift it full and heavy over the top of the 5' tank), then added a fertilizer tablet, and a lily that had outgrown my little pond. It floated a bit high, so I wiggled a rock in to the bottom. Now it floats with the top edge about 2" under water.

The fish can't eat my lily roots, and the lily won't dump gunk in the pond.

    Bookmark   August 27, 2012 at 9:51PM
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steiconi(12a-Big Island, HI)

As an afterthought, I added a tub of marsh plants that I thought would float, and it does! It's just the kind of soft plastic tub you might use to wash dishes. About 3/4 full of mud, pennyroyal, some kinda water grass, and even a water lily keiki, it floats just barely under the water surface.

I'm looking to see what else will float now...look out, tilapia!

    Bookmark   August 28, 2012 at 3:03AM
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Go to home depot and buy a sheet of stryofoam. You can use a drill or razor knife to cut the shape and size of holes you want. You can paint it if you want, but once your plants begin growing you wont see the color of the top. It will float with no problems

    Bookmark   April 23, 2013 at 8:01AM
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Thanks for all the tips..

    Bookmark   April 29, 2013 at 10:14AM
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Well, I'm going to try again this year but just would like to know...what is the size of these filters? they seem to be square but I could not find them at Home Depot. Also, are they a smooth or scratchy filters? I saw some that were much larger but I didn't think you had to cut yours to size. And then there's the holes. They seem to be quite large so I'm wondering how the plants don't float out of it?? I did try one last year, not exactly like yours but mine didn't work out well at all. I'm just anxious to try again. I promise I'm gonna try, I said try, to get this through my head.. Thanks BT

    Bookmark   May 10, 2013 at 9:15AM
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Love Development and Construction

I made two of these last year and at it again...thought I would post a pic of the media I bought at home depot

1 Like    Bookmark   March 20, 2015 at 6:01PM
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Shalom, made a larger island last year from a small plastic pond, used great stuff around the edge for floatation, always a challenge to how much to use, but it's easy to cut off it too much. covered the great stuff with pebbles , sand, ands some dirt to get a beach effect - been working well. I used a drill and made 1" holes for water and roots, use batting for the medium and as such you can also use some soil. When I got some of the land plans, I kept the small amount of soil to help them get started. Use job spikes or miracle grow plant spikes for fertilizer.

The foam insulation boards are easy to cut and shape as you want, can be painted.

    Bookmark   March 22, 2015 at 6:38AM
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