‘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 (sold by mail by places like Waterford Gardens). 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.

  1. Johanna says:

    So why no mosquitoes? Is it because of the plants on top of the water? I’ve always heard that still water allows the mosquitoes to lay their eggs, but if it’s got a bubbler or some sort of recirculating, that will keep them away. And of course I know fish in the water will eat the eggs. Or are your frogs taking care of the mosquitoes?

    The still, green surface is quite lovely. I’m having my shaded entry garden re-fenced this spring. Maybe I need a container pond there!

  2. Catherine says:

    Gurgling water is so soothing… give me a pond and a gin and tonic after a long day of toiling in the garden. My little pond has dragonflies that arrive to help with the mosquitoes and my green jumpers are adorable. Love the frog pic Margaret.

  3. Jayne says:

    I was interested in ordering the covers, but wonder if there is any chance they would “escape” the pot and get into the “real” pond on our property?

    1. Margaret says:

      Welcome, Karen. If you are very worried, I know some people use “mosquito dunks” made of Bt that you can also get at your garden center. But I have never bothered. See you soon!

      Welcome, Kathleen. Yes, I work at least as much as ever (all freelance, but lots of hours) but at least I am here, in my “patch of heaven” as you say, and doing it for myself, and much of it includes writing, thankfully. So glad to “meet” you, and hope to see you here again before long.

  4. Joanna says:

    I was wondering about the mosquitoes too. One of the biggest problems of mosquitoes in cities is small pools of water, so how do you keep them at bay? Apparently if a small copepod called Mesocyclops aspericornis is added to the water then there will be no mosquitoes at all.

  5. Kathleen says:


    I just found your site and I’m enjoying the pictures first. I’ll catch up with your writings as I go. But I’m craving summer in the worst way. We’re having a cold spring and it just snowed today.

    I bought your book today and am reading it as well.

    I’m a fellow gardener on my own little acre and quarter outside Seattle. I still have to work, so I don’ t have the time I’d like to do all I’d like. And I’m single, so there is a challenge to some of my ideas. But there is no where else I’d rather be than in my little patch of Heaven.


    1. Margaret says:

      Welcome, KCK. Yes, the cat does sometimes (as he does from both the in-ground frogponds here, too, and every depression in a stone that gathers a little bit of water). You could elevate them and they would be quite handsome (maybe not ones as big as these in the photos, but slightly shallower ones, put up on legs or a stand).

  6. virginia morningstar says:

    Any suggestions on where trough planters-cum-ponds might be available? My usual suspects only have asian-type pots and this dimension would work much better for me. I’m in SE Pennsylvania. Thanks for any ideas!

  7. Margaret Andrews says:

    I made a water garden like this for the first time last summer and was very pleased with the results. Placed on my deck, I never had an issue with mosquitoes or water overfow as my labrador retriever thought it was a very large water dish set outside for him. He agitated the pot several times a day and kept the water level in check. Topping up the water became a part of the daily routine of watering my hanging plant pots. I added some larger rocks to the pots for the birds to perch on. I plan on adding a few more this year sunken part way in the ground in my garden beds.

  8. Jenny says:

    You inspired me, although I decided to start cheap to see how it goes. Bought a water lily at Lowe’s and tossed it in a pot I already owned. The neighbors pond has duckweed, I’m going to go skim some off. Have you ever tried parrot feather on top of a pot? It’s an invasive thug on lots of ponds down here, so easy to come by.

    I’m kind of fascinated with the water lily. I swear I can see it growing before my eyes!

  9. sarah bennett says:

    Hate to ask this but what about rats? Any time I have had a bucket of water hanging around, rats invariably end up going there for a drink and end up in the drink (drowned). Do you have that problem?

  10. Julia Brown says:

    I have a 75 gallon water garden with a biofilter pump, and had billions of mosquito eggs until I bought a dozen cheap feeder goldfish every spring. Between the algae, bugs, and mosquito eggs, they require virtually no care or special food. About half of them don’t make it, or become wildlife food, but I always have at least 5-6 that are more than worth the quarter they cost!

    1. Margaret says:

      Welcome, Julia. I have fish in one of the in-ground water gardens, but just frogs in the rest. Seems like everyone gobbles up the bugs; no problems here, either. The food chain at work! :)

  11. Maryanne says:

    I am going to try a small pond container. I live in a condo with a very small yard, but I grow a lot of favorite plants and by end of growing season I have my own little jungle.I love it. A pond would be perfect.

    1. Margaret says:

      Welcome, Maryanne. I think you will really enjoy the little water garden. I have my seasonal troughs right near the door, and pass them many times a day/week — and everyone who comes in is always fascinated. Enjoy, and do stop in again.

  12. Kathy Sciamanda says:

    Hello all,
    I am still a little fuzzy on how the mosquitos are thwarted? We have a few goldfish that winter over in our heated horse/goat water. They think they live in Miami instead of northern Washington state.
    Margaret, I recently bought a “signed’ copy of your first book, (the pricey one) and am wondering if your signature looks like a line of ‘M’s’? Try as I might I can’t make your name out of the signature and was just wondering if indeed you signed it or not. I have read your new book and am half way thorough the first one. I savor it, a bit at a time, curled up with a good cup of coffee in my favorite chair.
    THANK YOU!!!

    1. Margaret says:

      Hi, Kathy. I have so many birds, frogs, etc. that I simply don’t have an issue — but I am not in a low, wet area. If you have a mosquito issue you can use the “dunks” (nontoxic) or put fish in.

      And yes, that caterpillar of MMMMMMMMMs is my name. Believe it or not, I think it says Margaret Roach. :)

  13. naomi says:

    I put in a little cheap pond (if 35 gallons is a pond) a few years ago and have never seen mosquitoes in it, and I live in New Orleans. Now, the bayou up the block, or damp ground – those can be problems. One feeder fish is now two years old and beautiful. That pot idea inspires me, and maybe I’ll finally get frogs bigger than a fly. I envy you the big guys.

  14. fern says:

    So you said initially that there’s nothing to worry about mosquitoes, but later, in response to someone’s question, you just said you never bothered with mosquito dunks. But that doesn’t mean that mosquitoes don’t breed in there. Have you ever looked closely at the water? If you see tiny larvae swimming around, that would be mosquitoes.

  15. Sharon says:

    Margaret, I’ve finally found the perfect pot for my own little water garden, but the azola photos at Catfish Logic don’t seem to be the same as the plant in your photo. Am I mistaken? Ready to order!

    1. Margaret says:

      Hi, Sharon. In my troughs I usually have a mix of Azolla and Lemna (the latter is called duckweed). The tiny leaves do grow over time (and the plants also multiply).

  16. Gwen says:

    Margaret, I enjoyed seeing your begonias so much. I’ve grown & loved begonias for many years but am puzzled by a new variety of an Angel-Wing I got late last summer. My sister gave me a cutting and it’s grown so big & pretty. It has dark green leaves with white specks all over, burgundy coloring on the underside. It has not bloomed and I can’t figure out why! Never had an Angel-Wing to NOT bloom profusely; however, this is a different variety than I’ve had. It’s a georgous plant without blooms, but it’s supposed to bloom. Any thoughts as to why no blooms? Love your blog and learn so much from you. Thanks! Gwen

    1. Margaret says:

      Hi, Gwen. Is it a cane type — standing tall and basically upright on “canes” or tall segmented stems like bamboo? So many things are referred to as “angel wings” now that I am not sure what plant you mean. If the old-fashioned cane types (which sounds like the leaves you are describing) they do tolerate and even like bright light, and need it to flower well. A thorough how to grow them factsheet from the American Begonia Society is here. Very young or very overgrown plants may also fail to bloom, in my experience. See if the factsheet helps at all — compared to how you are groing the plant, is thee a difference in the care/conditions?

  17. Donna says:

    Just bought a house with two lovely fountains, now full of tadpoles. I’m just trying to figure out how to clean out the old leaves and gunk without hurting them. Also, should I put anything around the fountains to protect frogs and toads. Just found your blog and am learning so much. It’s so inspiring.

    1. Margaret says:

      Welcome, Donna. I scoop the debris gently with a pond net (like a swimming pool net) and then place each load into a wheelbarrow, with some water in it, and sift through to find salamanders and frogs and tadpoles and eggs I have inadvertently disturbed. Then I eventually dump the leftovers in the compost. I have given up trying to protect everyone out back from everyone else — the snakes and occasional heron eat the frogs and the frogs eat the occasional bird and chipmunk and and and and … the food chain at work!

  18. Valerie Gillman says:

    I have a duckweed question. My duckweed doesn’t cover the top of it’s container and there is so much icky debree mixed with it-cottonweed seeds, rotten pieces of leaves, etc. I was hoping it would grow faster. It looks nasty. Will I have to take an afternoon and separate the duckweed from all the slimy things?
    Also, could you keep a dish of it over the winter to start a new pot in spring?

  19. Cindy says:

    A shout out to Catfish Logic and their impeccable customer service. My little water gardens rival the pictures of yours! Could not be happier with the end result of the water gardens or with Catfish Logic’s commitment to exemplary service.

  20. Rachel says:

    Heya Margaret,
    Do you know what that lovely begonia with the pointy variegated leaves is called all the way to the right? Do you have a particular vendor that you use for your begonias? Your book is lovely– just finished a few days ago. Would be happy to share some dahlia tubers with you next year if you’d like some in gratitude for the great and thoughtful read– I’ve got a small farm in CT. –R

      1. heidih says:

        Glad I read the older comments. I was going to recommend Kartuz for begonias as well. They are so passionate AND nice. Micheal never stops smiling. They are rabid hybridizers so you never know what you’ll find. I’ve been in other commercial greenhouses and a friend will yell out “this is the one the guys named after me” – plant friends – treasures.

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