Buy a bag of composted steer manure or Rose Tone organic fertilizer or Alfalfa pellets (horse feed)

All Clematis take at least three years to mature, some more and some less. Hard pruning every early spring will encourage growth, sounds wrong that pruning encourages growth but it does.

Completely agree with Buyorsell with her advice to you. One other thing if you are trying to amend a large area is to use Humus. It is readily available at our local city works department and soooo cheap in comparison to top soil at yard supply companies. We used it to fill in a whole flower bed and wow do my hostas and clems grow well in it.

If your city doesn't offer it then call around to the surrounding municipalities. I am sure one of them will have it for you.

I, too, have sandy soil, though with no clay. Be thankful for that - clay has water retaining abilities and nutrients, something sand lacks!

You need to start by adding as much organic matter as you can to that area by top dressing with compost, mulch, really anything that can break down and get the microbial life in that sandy soil going. Grass trimmings, your neighbors' grass trimmings, kitchen scraps and coffee grounds from the local store - I've used it all in the past.

And you can put semi-finished compost on top of the soil. Just keep it away from the stems. It will break down quickly as the weather warms up.

I'm adding as much organic material as quickly as I can, starting with the heavy feeders like the roses and clems, but darn it, a girl can only drink so much coffee!! (I'm pilfering the office coffee grounds as well...don't think I don't get a few weird looks with that!)

I don't have a whole lot of clay, just enough to make it get r e a l l y hard in the summer.

Will they stand partially rotted horse manure (obviously kept away from the stems) as well? I have more of that than anything, but have hestitated to use it in any real quantity for fear of overkill. It's mixed with pine shavings for bedding.

Horse manure partially rotted should be fine if used as mulch. Ask your local coffee shop for additional coffee grounds! And your neighbors for their grass clippings. The more biological activity you can get in the soil the better the system will be so that the roots can take up nutrition.