Yes. This is certainly doable.

Keith

Doable, but best practice? I say no. From my experience, if the upper graft takes and the lower one fails, then you have an unsightly and sometimes diseased portion below your good graft. Not the best situation.

Here's my suggestion - graft a little high to start with. Then if grafts fail you can reuse the understock and try another graft lower down. This avoids the problem mentioned above, since the top will eventually be cut off anyway. If you're worried about scion wood, cut some extra and store it in the fridge for up to a month. Just put a small piece of mostened paper towel in a zip-lock bag with the scion and place in the crisper drawer. Works great! I reused a bunch of understock last year using this method.

Good luck!

My understanding is that I should do the graft when the buds on the understock begin to swell. It will then take a few weeks to know if the graft "took". If at that time I realize that the graft failed is the understock to far along to graft lower with a refrigerated scion?

The understock stays graftable much longer than the scion. I have re-grafted understock 2 months after the initial graft failed, and it worked fine.

Grafting should be done when the understock is coming out of dormancy. I don't look for bud swell, I look for white root tips. Just lift the understock out of the pot and look for new, white root tips. This means the plant is coming out of dormancy. Also, be sure to cut the top few inches off the understock and allow it to bleed for 4 or 5 days before grafting. And don't water the understock. You want it to be relativly dry when you start grafting, or sap will bleed into the graft and ruin it. If you lift a potted understock it should feel relatively light in weight. A heavy pot means the soil is water-logged and the graft will bleed excessively.

After grafting, keep the whole plant on the dry side. I give mine, which are in 4" pots, about 3 tablespoons of water twice a week. After the grafts have healed and the scions begin to sprout, you can increase watering, but not too much. Its still possible to drown the graft for a few more weeks. Once the leaves have really started to unfurl and the graft is looking more like a little tree, you can start regular watering. This may be a whole month after you see the first signs of growth. The grafts need to be in a protected, high humidity environment for a couple of months and then gradually weaned off the humidity. If you don't have a greenhouse, you can make little tents out of bamboo skewers ($1.00 for 100 at Wal Mart)and baggies that will do the trick. This works well for me. I also mist regularly and use a humidifier.

Hope this helps!

There's a pretty active thread going on this subject over on the UBC Forum, if you're interested.

http://www.ubcbotanicalgarden.org/forums/showthread.php?t=60036