What is the natural soil like? Clay? Silt?

There is no need to dig out 4' deep, or even 2' deep unless there are large rocks. But if you will already have a backhoe there, might as well have them look for rocks down to 2'.

Roses do not need or want fast drainage. To check drainage, dig a hole 16" deep with fairly straight sides. Fill it and let drain to pre-wet the subsoil, unless it is already wet. Fill again, and if it drains 1" per hour, that is good drainage for roses. 1/2" per hour is tolerable but less than ideal.

If you have clay loam or silt loam, that may seem too heavy to you, but it is probably better than what you can buy at the nursery. You can get a soil test via county ag extension, or search on jar test and soil handling test to learn how to ID soil types.

Often the best course with heavy soil is just to dig 3" of manure into the top 12", leave the bed slightly raised above the surround, and keep it mulched with organic material. If you avoid digging or stepping on it when it is wet, it will improve over time and develop a crumbly structure.

All the above advice is good, I just have to reiterate that removing your native soil and replacing it with fill is usually detrimental to the health of your future garden. If it were me I would line the new bed with some sort of decorative edging so that you can build up the soil a few inches with amendment and mulch the way Michealg describes.

If you aren't in a hurry to get started, topdressing with half-composted material and then covering with mulch and letting the area sit until fall should improve the soil greatly. Worms come up to eat and do a very good job of loosening and enriching the soil. I've noticed with the clay soil in my area that when I do this it makes digging and planting much easier than when I just go straight for the shovel.

This post was edited by peachymomo on Tue, Apr 16, 13 at 11:08

Digging out some of the soil and adding compost in it's place is a good idea, but don't dig out 4'. It will settle and you'll be left with a canyon. I would dig up maybe the top foot or so and mix with compost.

Thanks for your answers. Your suggestions will make
the new bed a little more work, but substantially less $$$.

Andrea K

Wow! The responses to the original post are so enouraging . It doesn't appear that I need to do all that much with my native soil (clay and minimally sandy). Conflicting advice that roses need a huge hole 2-3' deep and wide, native soil replaced with a soil mix, loads of organic material (at least 1/2 native to 1/2 organic), fast draining soil, etc., caused me to almost panic about the best approach for planting my container roses in ground. The advice given debunks at lot of what I've been told and read--thanks to all who took the time to reply to andreark!