‘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. 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. Broken Barn Industries 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.

    1. 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.

      1. Lauren says:

        Hello I used to save pond plants under low hanging fluorescent lights. The plants were all in the plastic bins that you get spring mix in at Costco. The only problem I had was that water hyacinth would get spider mite and I would keep the population down by spraying with Neem and then washing the plants obsessively before returning them to the pond along with the fish come Spring. The other plants did OK. The fish never showed ill effects.

  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


      1. Lauren says:

        Waterford Gardens in New Jersey has just about EVERYTHING plus the people who work there have always been helpful and patient. Also Garden State Koi is a good place in Orange County, NY.

  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.

      1. 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!

    1. Lauren says:

      You can put a little bit of a mosquito dunk Bacillus thuriengensis x israelensis kills just the mosquito larvae and not fish, frogs, excited bathing dogs, etc.

  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!

    1. 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. 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.

    1. margaret says:

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

  10. Colleen Jones says:

    I love the duckweed water feature :)
    I have looked but not found a pot with glazing on the inside- is that crucial?

  11. Katy Jones says:

    I have a nice looking “glazed interior” fibreglass hypertufa-type container that would make an ideal water trough in my back yard, but any advice to deter raccoons? These critters in downtown Toronto will invert my watering cans, whether or not I unintentionally leave the water in them overnight. They also race the skunks for the lawn grubs while the rabbits and voles dodge the neighbourhood cats and the hungry birds wait patiently by the squirrel feeders every morning for me to refill them. Urban nature in its chaotic glory.

    1. margaret says:

      I can’t say I have any secret ways to deter raccoons, who are very crafty, persistent and nimble in their overnight antics here in my rural garden, too. Obvious stuff is not having any food or other attractants (which sadly includes water!) around…no garbage…and so on.

      1. Margaret, I absolutely love this idea. One question: how deep does the container need to be – that is, what’s the critical mass level for plant health? I’ve just seen a wide black rubber tub that holds 15 gallons – do you think that’s enough? I have always wanted a little “piece d’eau” in the garden, but didn’t want the pump, the underground pipes, the hum. I will try this at once! Tell me about the size of it. Thank you!

        1. margaret says:

          I don’t know the ideal volume/depth but just that if we think about the shape/volume and how hot the water will get in a a particular shape/size of vessel (especially if it’s in the sun!). Obviously the more surface area compared to depth, the more light gets in and the less “insulation” there is in the volume of water. My larger of the two troughs is probably 2’x3’x18″ high, and the walls are very thick, which probably helps, too. I think you can do this in any vessel, but not in a small or shallow one in full sun. I think it will have to be an experiment. The floating plants are critical — and again, if the water gets too hot they won’t be happy, right?

  12. Cindy donahey says:

    Found a scallop shaped container, quite heavy . Used to contain a fountain. Put some clay over the broken concrete part and put moss on top. Still undecided on how to stain or paint the concrete. Stuffed leaves around the bottom and soil on top. Nothing planted yet. Need a base in back. Will put some kind of container on top with a few small holes to seep water in.. maybe a big cat litter container wrapped in burlap. Want sand in the container and maybe some shells. Maybe a little vinegar in the water to keep out mosquitoes. Not sure exactly how it will work out.

  13. Lauren???? says:

    I have not yet gotten to the pond agenda in new home but I had a little pond in old yard. I dug it with a little spot on one side, a little low and on the edge there was a barrier of small rocks and gravel that if the water level got too high it would overflow down a hill but first all was strained through this gravel. I had a big piece of slate from the dump on top just in case there was a super cell deluge and somehow the fish could getwashed away. No fish or floating plants ever were lost.

  14. Nancy Helterman says:

    I set up a round water garden earlier this month in a pretty ceramic pot that previously housed a now-defunct office-gift plant that lasted several years. I had to scrounge $5 worth of duckweed from a local garden center that clearly did not have it for sale–it was incidental to larger, more wonderful plants–and came up with a bare 1/2 cup. Spotty at first, in no time at all the surface was covered! Thanks for sharing information about this great addition to a modest garden!

    1. margaret says:

      It does shade the water and help prevent algae, and I like the way it looks, too. Nice to hear from you, Nancy.

  15. Hi Margaret, I was so inspired by your water trough garden when I saw it in your garden a couple years ago, that I tried it. I found a glazed pot about 2′ deep and put it on my deck. I was shocked and upset when I found a drowned chipmunk in it, I don’t have the guts to try it again…

  16. Your water pots look elegant with that mossy stuff growing on top. I am glad to hear you don’t have mosquito problems from them. Those sweet little frogs would be worth the effort. Your begonias look so healthy. Begonias are one of my favorite plants.
    I just ripped out a small, but heavy, water feature I made 21 years ago. Not sure how or what I am going to do to introduce water into a feature on my patio. This seems like a timely post for me.

  17. Kathy Farnsworth says:

    It’s December 2019 and I don’t know if my post is too late. I find myself rereading the information about your mini ponds. They are so beautiful and peaceful in your garden. I had a lovely deep copper basin in a previous garden but two baby robins drowned and I felt terrible. I put a large rock in the bottom. Do birds ever drown in your water vessels? Does the duckweed signify a deeper pond that birds instinctively know not to venture in? Thank you Margaret.

    1. margaret says:

      Hi, Kathy. My water gardens are 3 feet deep, and 18 inches deep. I have never in 30 years retrieved a bird out of either one, though birds use the pools nonstop each day year round. I don’t really know how the birds understand how to navigate the water safely, but perhaps because it is big enough (the surface area is like 12 by 8 feet) and realistic-looking, I guess it is no different to them from natural vernal pools or other natural small water features. Don’t really know, but no casualties (and I have fished out several chimpunks and once a woodchuck!).

  18. Kitty Martin says:

    Would you be willing to identify the lovely plants in pots behind (and beside) your water gardens? They are beautiful.

  19. Winnie says:

    Can you please tell me what the plant behind the pond in the picture is? It’s the one directly behind, a bit speckly. Loved this article.

  20. Sharon B. says:

    How do your frogs get in and out of your pots? Are they really able to just jump in — and more importantly — jump out?

  21. Therese says:

    Yikes!! The first thing I thought of seeing these deep containers was what about birds? I put a few rocks even in my birdbath for birds who can’t get out otherwise. That flat green surface really is beautiful but could perhaps look like a place to land for the unwary.

    They are beautiful, though. Here in Houston many people with watergardens use mosquito fish.

    1. margaret says:

      In 20 or so years I have never had a bird accident in these or the bigger in-ground water gardens. Have had chipmunk fatalities, and the occasional mouse.

  22. Lori says:

    To assist bird or frogs I put a brick at one end and stand a small pot planted with reeds on top of brick leaving it just above water level. This way they have a spot to climb up on.

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