aerialz:

You are correct that nearly all cherry trees sold by nurseries are grafted. (Although budding is also a technique that can be used to propogate cherry trees). The graft should be visible as a suture a few inches above where the roots begin to appear at the bottom of the tree. If you look carefully you should be able to see where these two components (rootstock and scion) were joined and grew together. The graft should always remain above the soil line when a grafted tree is planted to take advantage of the qualities imparted by the rootstock. If you plant a grafted tree too deep, it is possible to bury the graft, at which point the scion may also begin to throw roots.

The best way I can think of to avoid planting another sweet cherry would be to learn to graft, and add an additional variety to your existing tree. You may think grafting is way beyond your capabilities, but in fact it is not if you give it a good try. Grafting advice and scion exchanges are frequently offered right here on Gardenweb.

Of course, I am the one who told you it is likely to be hard to raise sweet cherries in your particular climate, but you never know when you might get a good year a good crop. You will, however, have to watch for diseases, dormant spray your trees, and prune out disease cankers when and if they appear.

Don Yellman, Great Falls, VA

Cherries are hit and miss in much of California. Black Tartarian have a chilling requirement of 700 hours which may be a problem for you. Call your county extension office for the average chilling hours where you live. Most cherries have a similar chilling requirement. Black Tartarian is a very soft sweet cherry, my favorite for eating right off the tree. They don't keep well or ship, but are great for the home gardener. Al