Several weeks ago I planted a little hydrangea (Strawberry Vanilla) that also looked like two sticks. First, I soaked it overnight in a pail of water, the next day I planted it in the ground in amended soil, and I watered it deeply and well. For the next week I made sure it didn't dry out and I provided it with some shade in the afternoons.

The result: that little sucker has been growing like crazy, lots of green leaves, etc. There's nothing for me to do now but make sure it doesn't get too dry if we don't get some rain soon.

That's all you really need to do, especially with those little ones. Arborescens are willing growers, judging by my Annabelles.

Kate

Thanks Kate, that sounds promising. How about pruning it now? Will this encourage branching?

Here is the baby (in the original pot):

Myself, I would say absolutely do NOT prune it. It needs as many leaves as possible to soak up all that sun-drenched chlorophyll that will make it grow. Besides, I don't believe pruning encourages branching on hydrangeas--at least, not as far as I know.

Your little fella is looking good. However, that pot seems a bit small. What you want right now is lots of good root growth. Wouldn't a larger pot facilitate that? (On the other hand, I never grow my plants in pots, so what do I know?)

Kate

Thanks again Kate! It is a 3" pot in which the plant arrived. I already potted it up into 2 Gallon pot with some bone meal to stimulate root growth. My experience shows that potting up small shrubs and perennials is better than planting them directly in the garden. I'll keep it potted till fall.
Thanks for your help!