the base issue imo ... is how you will keep enough moisture in the shallow media.. in full sun.. during the heat of the day ...

once you figure that out... the plants probably wont matter ...

the larger the plant .... the larger the requisite root mass necessary for success .. so you are probably looking for small plants ..

i suggest you fail wildly.. and then talk her into your succulent idea next year.. lol ... you always have the option in mid august.. of dumping it all out.. and going back to water for the birds ...

and suggest to her.. lol .. she cant like the premise.. and then change the premise completely.. and then blame you if it fails ...

its like comments i see on food recipes ... ' i like this recipe.. but i changed the meat.. the process and the spice palette ...' ... really??? what exactly about the recipe did you like.. crikey ...

your choice of a plants that dont mind heat and blinding hot sun ....and dont need a lot of water is brilliant.. good luck finding small perens that fit the same bill ...

it probably doesn't matter here.. but min winter temp... aka zone.. doesnt tell is much of anything... how about a big city name ... since z7 ranges from the wet PNW to the soggy swamp lands of the SE .. to the desert area of the SW .. and half of everything in between ..

good luck with MIL .. sounds like you might need it ...

ken

I'm in western North Carolina, in the foothills before you get to Boone. Climate is the same as Greensboro or Winston Salem, but I'm in a much more rural area.

The thing with my MIL is that I absolutely adore her, and she loves me just as much as I love her <3 I built a flower garden for her a couple of weeks ago with the hardiest plants I could find, because she really doesn't understand plants enough and will inevitably overwater, underwater, step on them, etc. But she'll get super excited with color, and then super depressed when they don't come back. So I was really hoping that there might be an option that I'm overlooking :-(

I THOUGHT about sticking day lilies and irises in the middle, then surrounding it with mondo grass. It's not really the look I would like, but then it would be virtually indestructible! LOL

I'm sorry to burst your bubble but I don't know any ANY perennials that would survive in only 2-3 inches of soil other than the succulents already mentioned or some very flat, mat-like spreading groundcovers. Sorry but almost no hope for success with daylilies, iris or mondo grass with that soil depth unless you are out there daily or possibly 2-3 times daily to keep everything hydrated.

How 'bout something in a container with some depth to it for the centerpiece and then the low growing stuff planted around? Will still have be very diligent with the watering, tho.

i got it ...

say you consulted with some new garden wizard friends ... that being me and gal .. lol ..

and tell her the only chance of success .. was that bright idea you originally came up with ... mostly because apparently you are a fledgling wizard ....

but you do have a solution if she insists ... and then whip out a bunch of fake flowers from hob lob.. and stick them in the bird bath ... tell here they are extraordinarily long lived.. and if they get dirty .. she can swish them around in a pail of sudsy water .. then dont need watering ... or any other care ...lol ..

ken

ps: if you did it without telling here.... might she ever notice???

Well, a smallish container in the middle (like 6" deep) that I could hide with rocks and/or plants is very doable! I could potentially stack up some larger river rock around the pot, then ice plant, creeping thyme, or portulaca in between the rocks?

Watering is a little bit of an issue, though, because I know her; she'll go through periods of excitement where she waters everything WAY too much, then she'll get busy (or depressed) and forget for a week or two. I would obviously drill drain holes in the birdbath so there wouldn't be an issue of too much water, but it could definitely dry out if we got for a period of no rain and she doesn't remember to water.

Hahahaha @ken_adrian Adrian MI cold Z5 , that's not the WORST idea!! LOL She did insist on some pink flamingos in the garden I made for her, so in all honesty she probably wouldn't even hate the fake flowers. I know that she really just likes bright colors...

What if I DON'T drain the bird bath, but put a container in the middle and surround it with rock. Then I could plant morning glories and moonvine in the container and let them trail down.

I agree with the idea of a pot or container (or a couple of them) in the center, although even these will have to be checked for water. I think I would go with annuals - this would give her a longer bloom period (i.e. longer period of color). Unless you use, as you say, a creeping sedum around the edge, and I love the idea of portulaca. These are little bloom machines for me, along the edge of the asphalt road, in shallow, sandy soil, even growing in the cracks in the road.

Maybe, looking at your last idea, don't drain the birdbath, put a container in the middle and maybe cut the bottom out of it to facilitate water uptake, and then plant your trailing plants to go down over the rock and the edges.

I think the problem here is that you don't have either a neglectful gardener (like me!) who forgets to water, OR a too-attentive gardener who overwaters, but a gardener who fluctuates between the two extremes, so it's hard to know which to plan for, drought, or overwatering. So it's a tough call as to what to plant.

I have to say, you got me googling this idea and I think I'm going to try this! I might actually buy a birdbath just for this purpose because I think it's a nice idea. Good luck with your mother-in-law's!

:)
Dee

The birdbath doesn't have drainage right? If you water it, you'll have to guess how much water is the right amount. And if she forgets to water it, 2-3inches of soil in full sun, that's pretty awful treatment of any plant you put in there. I'd say at the height of summer, she might need to water it 2x a day.

I have to agree with Ken, that you actually had the best idea, of using succulents. Don't they use them in roof gardens? They might adapt to those conditions, but, they might not either. Does a roof garden have drainage?

If you wanted to use your idea of potting up a morning glory or something, in a pot surrounded by rocks and let it trail, that could work if she can take the pot out, water it, drain it and put it back. But a morning glory takes quite awhile before it blooms.

The only other idea I have is that you change the location and put it in full shade. Plant up a fern/moss garden. A lot of ferns won't like drying out, but Japanese fern is better at that than most. Help her begin to appreciate plants that don't have flowers. You can use different foliage colors, add a heuchera or small hosta. I don't know if it will work any better in the shade, but I only know I wouldn't want the job of taking care of plants in a birdbath in full sun.

Anything you do, will be an experiment and as long as you are comfortable with how short lived it may be, then I'd think your ideas are just as good as anyone else's. The daylily with grasses is a nice idea, especially if you keep it in a pot that can be lifted out to water and drain and return. The portulaca idea that Dee had, they are really succulents, right? They may trail.

You could look at a list of rain garden plants - they are supposed to tolerate feast or famine conditions with water.

And this is going to be outdoors all winter? I grow Arborvitae that stay in pots year round and I remember having to look for shrubs that were 2 zones more cold tolerant than I was. I think Arborvitae are hardy to z3, so I had 3 zones and they have not had a problem at all. You might need to use plants that are hardy at least to z5. Maybe you could add some small bulbs to come up in a moss/fern garden, like Scilla or mini daffodils, or snowdrops.

Sounds like you and your MIL enjoy your relationship, hope you figure out something that is successful.

To riff on PM2's idea, I had been thinking if you move it to the shade you could try coleus. There's some very pretty foliage to choose. Now that I think of it, I wonder if heuchera would work - again, lovely foliage to choose from and I think shallow rooted, and may work okay in drier situations. On the other hand, maybe some impatiens would work. I've seen them do well in pretty damp situations, if your MIL overwaters.

But again, it comes down to not too much water or too little, but inconsistency....

:)
Dee