They do fine, depending of course on what, exactly your clay is like. If it puddles you need to put in drain lines or plant in raised beds filled with coarser soil brought in for the purpose. Do not plant in pockets of amended backfill, especially in a heavy soil as these may attract and collect water. After the amendments decompose (sometimes within a year in a hot climate) then you are left with the same soil conditions you had in the first place.

throw all the coffee grounds to that clay area that you can get your hands on. Check with Starbucks, Krystal, Waffle House, Cracker Barrel, et al, and keep them coffee grounds coming. The worms will come and they will work your soil.

P.S. By this time of year, I have quite a bit of corn meal left from all the cornbread, dressing, hush puppies, taco shells, burritos that I never cooked, and I mix that in my soil also.

Ask your county extension agent if gypsum works to lighten your clays.
Do you have topsoil above the less organic rich clays?

If you can't do the entire bed, then I usually do a 2 ft wide and 2 ft deep hole. I think back fill the hole 1/2 way with the loosened soil. I mix in bone meal and a topsoil mix. I usually mound my roses somewhat.

I have clay, but in most parts it's pliable enough. You'll also want to mulch very well after planting. This helps keep clay cool and moist.

Clay is actually a great starting medium for roses, but it does depend on whether water collects there or if it's on enough of a slope to drain slightly. Generally you will want to amend by layering the organics on top of clay (either as the top part of a wide, shallow hole or entirely above grade, again depending on drainage) rather than by working them into the existing soil, which tends to be counter-productive. Mulching on top of that will help reduce moisture loss, plus it keeps the soil cooler, which helps your amendments to last longer.

I have always heard 18" x 18" would do for rose. As for the clay, I have hard clay soil, and I think the roses like the clay because it holds water. Now I did amend the soil with old horse manure dirt mixed in with the clay, but you could amend with other stuff also. I personally think the sandy soil idea for roses is wrong.

With large plants like trees and shrubs amending small planting holes is basically always counterproductive, better results from plants in unamended holes on same sites in organized studies pretty consistent. Anything that puts a plant in a pocket of one soil texture surrounded by a different texture is likely to produce problems with how water moves into and out of the amended area. During wet conditions on heavy soils a new plant is likely to be sitting in water, during dry conditions the unamended soil around the hole may attract water away from the plant. The stresses created by these adversities result in less growth than if there was the same soil texture throughout. Amending the entire potential rooting area of the new plant can give it a uniform soil texture, but there is still the problem of the organic amendments decomposing and disappearing well before the shrub, tree or perennial is no longer being cultivated on the site.

Placing good topsoil on top has the advantage of a mineral component (sand, silt, clay) being part of the material used, the whole thing is not going to subside and leach away. Likewise structurally stable materials like sand can be used to break up a soil throughout an entire bed and keep it that way, but huge amounts must be used in order to produce the desired effect - unless the existing soil already has a fairly high sand component.

Where berms or mounds of topsoil are not adequate wetness is best dealt with by installing drain lines, with new plantings going into the existing soil afterward. Organic matter can be supplied as a mulch, as nature usually does it.

How about clay that's full of rocks---many of them large? I don't think a layer of amendments is going to solve my problem.....

Colleen

Plants don't mind rocks in their soil as a general rule. If you find you can't drive a shovel down deep enough to plant in the first place, then you could consider mounding up significantly with new soil above that. The rose roots will probably find their way down into the clay and rocks from there. Planting above literally solid rock is another story altogether, of course, and there you basically need a raised bed.