Kat,
Ultimately, YOU are in control of how big it gets - they can get very big, like any other willow, but my own personal preference is to whack corkscrew willow back to the ground every couple of years, and keep it as a multi-stemmed shrub. The vigorous shoots that come up each time you prune it may grow 5-6-10 feet in a season, once it's well-established, but those vigorous shoots are much more eye-catching than is a big old curly willow, which will, from a distance, look not unlike any other old streambank willow.

I've had corkscrew willows for about 4 yrs now and they never get a chance to "mature" So many peaple want starts off them that I'm constantly whittling away at the main trees and rooting the cuttings in water I have one in a 2 gallon pot, sitting on the east deck just for peaple who come in and want starts. Strong

Don't throw out the water you root the cuttings in. Save it for a rooting medium for other plants. The willow gives off something that stimulates plant growth. I've used it and loved it. I keep me corkscrew willow about 6 feet tall. Good luck. Mary

When is a good time to cut it back? Mine's getting pretty scraggly lookin'!

I have been looking into to getting a Willow Tree for my yard. I have heard that the Willow Tree's root system is very destructive and will break water pipes, septic systems, natural gas line (?) etc. Are the roots of a Corkscrew Willow Tree this bad. Will I run into the same problem.