For attaching, you can use those suction cups.

I have read that the same plants in planters may not attract the hummers as well as those plants being in ground. Maybe size plays a factor.

But for some plants that reputedly attract the hummers, petunias should work. I haven't seen them feeding from the petunias I have, even right next to a feeder that they come to. Empress of India nasturtiums also should attract them.

But I did see an interesting idea. There are some mini-feeders that hang on hooks which can fit into planters (stick the mini-shepherd's hook into the potting mix). You could have a pot of red flowers that grow well in pots, and then hang those feeders in it.

my best success. Has been with a small bird feeder attached by suction cup to a second story window above a trumpet vine the hummingbirds like. Not sure if they feel safer being high up or come for the trumpet vine and go to the bird feeder if it he vines isn't in bloom.

Considering a mix of petunias, foxglove, and bleeding hearts basedartly on local availability and price,.

We get only ruby-throated hummingbirds where I live. I don't know where you live or which species you have. In my experience, while the rubies look at petunias, they don't feed from them. I don't think petunias have any nectar available for them. I wouldn't put foxglove or bleeding hearts in a window box because they only bloom for short periods and they are large upright plants.

Which direction does your window box face? Is it shade, part shade, or full sun?

If your window box is shaded and if fuchsia does well in your area, it might be a good choice. Most of the modern fluffy hybrids don't have much to offer a hummingbird, so besides the right climate, you need specific varieties known to have nectar. The honeysuckle fuchsias, F. triphylla, get used by my hummers, but my local places only carry upright triphyllas. You'd want trailing fuchsias for the dangly look. I had a simple-flowered one named "Dainty" that the hummingbirds enjoyed. I haven't tried "Marinka" yet but other hummingbird gardeners have recommended it.

In sun and heat, fuchsias are doomed. There are more options for sun.

Lantana can be a large plant but also comes in window-box sized versions. Check labels to get an appropriately sized one. Some varieties dangle a bit but the overall shape is a mound, and it's more of a butterfly plant. I have seen the hummingbirds use it a little though.

Calibrachoa aka Million Bells trails beautifully. Some people have seen hummingbird use. The birds ignored it at my house. Probably depends on the specific variety and the food preferences of your local birds.

Would you be content to have upright plants for the birds, and cascading plants for looks?

Salvia coccinea does not dangle at all. But the hummingbirds love it. The "Summer Jewel" series is bred to be more compact and that's the one I'd try in a window box.

Salvia greggii is sold as a perennial to plant in the ground, and grows as an upright bush. I had one in a window box last year and it did very well. The hummers used it regularly.

Cuphea "David Verity" is a hummingbird favorite but gets huge. Not a window box plant at all. The new Cuphea "Vermillionaire" looks similar, is supposed to be smaller, and might work, but since it's new this year no one knows yet how it rates with the hummers. Random other cupheas are more likely to be useless than not.

Great information, Edie. Especially useful about fuchsia, as I tried it last year unsuccessfully. Now I know why. Thanks.

To add to the list, Bouvardia ternifolia is a brilliant clear red, hummers love it. Blooms non stop in either sun or shade and naturally flops. Available from Logees and Plants Delight has one that is more vigorous and hardy in Zone 7.

The location is coastal Massachusetts, Zone 6. Still trying to decide where to put the window box, but probably facing Northeast or Southwest and in full sun. Not sure of the species of the hummingbirds, but I suspect ruby ruby-throated.

The theory is the flowers will be a big flag to attract the birds to the window we have the feeder at. We've noticed a lot more birds come to the feeders that are near flowers hummingbirds like.

I 2nd Edie's recommendation of Salvia coccinea Summer Jewel series. I have both pink and red. I planted them in my containers about 2 weeks ago and the hummers hit them a couple of days later. I have had some red SnapDragons Montego series that the hummers visited last year.