‘instant’ water garden: try seasonal troughs

begonias outside

NOTHING ADDS MORE TO A GARDEN THAN WATER. Just ask the birds, frogs, and insects—oh, and human visitors, too.  It’s a magical element, providing sustenance and visual fascination (auditory, too, if you can make it move). I just hauled my simplest, seasonal water gardens—two big, glazed troughs I fill spring through fall, then stash—out of winter storage, and ordered the plants I need to get the look above. The details (and no, nothing to worry about re: mosquitoes, really):

Yes, mosquitoes: That’s the most common question I’m asked when I lecture, when people see these photos, above and below, among my slides. “What about mosquitoes?” After that: “How often do you have to change the water?”

Making an “instant” seasonal water garden—meaning no plumbing required—merely requires a watertight vessel, water, and some floating plants to shade the water surface. I top up the liquid as needed during the season, but do not swap it out completely.

Containers can be anything that holds water, including galvanized cattle tanks; earthenware pots with glazing at least on their interior surface (like my big troughs) and no drainage hole; or some other found object.

Level the pot or pots first (use a carpenter’s level), while still empty, and insert shims beneath, such as from an old shingle or pieces of slate, to adjust and stabilize. Once you add water, forget moving the pot if it’s off-kilter.

frog on lip of troughI prefer to place these temporary water gardens in a part-sun spot, rather than full sun, to keep algae growth down. The shade provided to the water by the floating plants like Azolla (fairy moss) or Lemna (duckweed) that I use helps with that, too (a source I use for mail-order). If your garden will go in full sun without a full cover of green, consider dyeing the water black with a non-toxic dye to help shade out algae instead (and hide all the underwater plumbing parts).

You can add fish if you like, but I don’t, since they are easy prey for cats, raccoons and the like. The frogs, above, add themselves at my place. Fish or frogs will eat mosquito larvae and mosquitoes, and I have no issue with insects, with my water pots in bright indirect light and covered in floating plants.

One funny note: If the pot is topped up to near the rim, heavy rains will cause overflow—and not just of water but also floating plants, which will likewise go overboard. Though they spread fast and make more, more, more all season in the water, you don’t want your velvety surface of green to go running down the path or into nearby soil, where the thousands of tiny plants would be impossible to recover…trust me, I have tried.

Don’t overfill, or instead cover the pot or scoop the green stuff into a dish and keep inside during big storms.

April 6, 2011


  1. Rachel says

    Hi Margaret, Logee’s is big trouble for me! I love them so– I always walk out with so many plants! I’ll check out Kartuz–thanks for the tip and the link to the other post. Feel free to just email me any varieties you like of dahlias anytime– best viewing on my flikr site… Anyway– enjoy July!

  2. says

    As of now, our “water feature” consists of two blue plastic rainbarrels with a few fish in each to keep the mosquito larva down. Maybe someday… (probably should send a link to this to the mister, try to get him inspired).

  3. Rosemary Race says

    Hi everyone
    I’m going pot crazy myself, on a swap with a buffet for 3 huge tall gray pots!
    I also bought a greeny yellowy large round pot with swags and gorgeous faces on it and of course I have my terracotta pots and half barrel pots all of which some have seeds and cuttings growing in them.
    I had a water garden ages ago and yes I got mossies with the gold fish and water plants just didn’t bother me.
    Now I have seen your water pots I’m going to get my water pot out and refill it and put my water plants in it again putting it next to my grapevine.

    • margaret says

      Hi, Audrey. I think I could do it with Azolla if I had the right conditions (a fish tank with light maybe, or a bucket in a cool but not cold greenhouse) but I don’t bother, honestly. Lemna is technically Zone 4 hardy so it would happily overwinter here — except for the fact that I have to skim and de-muck the pond in fall and spring, losing much of it, and then I get thick ice on the top all winter that it gets frozen into. I always have some make it anyhow. The Azolla is Zone 7, by the way.

  4. Sndy says

    Margaret hello

    Where do I find the Duck Wee & Azolla , The only water plants I have seen in my area are
    Water Lilies. Your help would be appreciated


    • margaret says

      Hi, Sandy. UPDATE: I used to get them from one place that closed after many years, but in 2015 I got them from the floating plants department of PondPlants dot com (mail order, online catalog).

  5. Heather says

    You didn’t say what you do about mosquitoes. We have a terrible problem with larva in our bird bath, I have to dump it and refill frequently as soon as the weather warms a little.

      • margaret says

        I keep the pots in a bright but indirect-light spot, so they are not nasty and algae-filled, and they are also covered in the floating plants, which shades the water and seems to keep it nice and not swampy/mosquito-laden. Also: small frogs usually take up residence in each pot for the summer, so forget mosquitoes with them on duty!

  6. E says

    Margaret, just tried the link(s) to Catfish Logic. Looks like they’ve been hacked. Every way I’ve tried gets forwarded to a clothing outlet. Thought you’d like to know, plus so would they.
    Do want to try my hand at water gardens. Thanx

  7. Susan B says

    Your troughs are beyond beautiful in and of themselves! Did you just hunt around in the planter section until you found them, and sealed up any holes, or did you look specifically for “water garden” containers, or did you just get super super lucky one day? :)

  8. mew says

    Hi, Margaret, thank you as always for all this great info. I just wondered how many plants you need to fill each size of container you show, the small round and larger oblong, for reference.
    Happy gardening!

    • margaret says

      I put the floating pond weeds, Azolla and Lemna, on my in-ground water garden, too, so I order a lot. They multiply quickly, however, so even a small amount (maybe two cups in the smaller trough and three cups in the larger) will result in fast coverage. Some mail-order places sell by the pound, others by volume.

  9. says

    Hi Margaret,
    I loved your water feature idea. It is so simple and easy to make. I am a bit worried about mosquitoes but still very enthusiastic to make one. It is hard to find plants for water container in my locality. So I use only water hyacinth and Froebelii in my container. Thanks for sharing such an easy idea.

    • margaret says

      I have to order all my water plants by mail; nothing very interesting sold locally. Glad you liked the trough garden idea.

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