Um, nothing useful really - you'd have been better off with the variegated version for that only reaches 20 feet - the one you have wants to get up to 50 feet. They don't need pruning usually, so you'll just have to risk it if you're trying to grow it in the wrong place and keeping it small.

Hi Hick, they certainly do throw out water-shoots (which I guess is what you mean by poles) as a response to pruning, in fact mine does that periodically even without being pruned.

You can cut them back pretty much as hard as you need without risk of killing the plant, but the tiered growth shape, for which they are so well known, probably won't reappear.

Your best bet might be to cut back and watch carefully to see how it responds. Then, if it does throw up multiple new growth shoots, further remove all but one or two of these shoots to encourage it to restore it's tree-like shape.

Hallo Hick, apologies for picking up on an old thread but wanted to ask you about your Cornus and its growth rate - i'm tempted by a really good deal on a largish specimen (it's about 2m) and am wondering how fast it's likely to grow before I have to potentially ruin its form by pruning. Like you, by the time it hits 4m it'll have well outgrown its space. How long has yours taken to get this large? a reply would be much appreciated! thanks!