As many as you can get your hands on!

I love Heuchera / coral bells & have several borders of them in various spots around front & back yards. I would consider sun & heat exposure of your spot when choosing varieties. Seems like darker colors hold up to sun & heat much better & definitely try to install a drip water system so can be watered from beneath & keep leaves dry. Well watered Heuchera stay more lush in heat. For a long stretch as you’re doing I'd also want to look at a plan for color scheme & mature size. I’d do color groupings for impact & definitely consider color of plants or house that this border might run in front of. . And, alternate placement in zig zag rather than straight line line formation. If you cut flower spikes as they dry up, flowering will continue all summer. Expect lots of hummingbirds!

ETA - also, do you know that heuchera is very easy to propagate in spring? If they get too woody as they mature, just break off a woody stalk section, stick in dirt & keep watered. Great way to get more of a certain color.

ETA: I think you’ll get lots of input if you also post your question in a couple of the gardening forums & it would be helpful to know your location. I'm in PNW - you might be in midwest - very different climate!

Thanks for the info! I'm in the midwest. This is for an eastern exposure, so sunny in the morning, less sun after noon. I want to use some heuchera richardsonii sp. and intersperse it with some decorative varieties for color.

Had to look that one up - looks like it‘s all green. I’d want to mix in some fabulous colors with that one. You’re in midwest so cold winters… here’s some of my colors in west facing back yard - along the paver edge. Thos is a fall picture obviously!

Looks like a rainbow, love it!

@faycosta Yes! Exactly why I love Coral Bells. For my locale, they’re year round color & love the Hummers they attract! As good as flowers only….

KW has offered good advice.

I am in central Ohio and have many heuchera - One lime green variety thrives in full sun and has grown to over a foot across. Several purple varieties (like Purple Palace) also thrive in full south sun. The more amber/orange/pink varieties have needed more shade, though, or more watering if in mostly sun (the full sun tolerant ones do fine with the natural rainfall, unless we've hit a midsummer stretch of little to no rain.