can you post a pic..

and can you define what 'fuller' means ... to you ...

i doubt you can kill them if you run them over with the truck.. but beyond that.. i cant give you an answer ...

ken

I prune my barberries, especially three big old ones, almost continually. Just keep trimming it up and it will produce denser and denser growth. Let that harden, and then do it again. I started with some very big straggly bushes and now they are quite rounded and dense (you can no longer see the inside much when foliated), after about three years of chipping away at it. Don't expect immediate results. You can also occasionally prune out up to a third of the oldest stems from the bottom to encourage new bottom growth, which I have also been doing. Think of it as a combination of rejuvenation pruning (you can google it) and shearing. These are very, very tough shrubs.

I hack about a foot off my 'Crimson Pygmy' barberries every spring with hedge shears. They aren't so small for me, 4' x 4' They just get denser and grow more after I shear them. You can't kill them by pruning.

When you do prune, wear strong gloves. The thorns are extremely sharp!!!

I just lightly pruned some crimson pygmy barberries and was surprised to see that the areas where I pruned are now green. Will these areas darken to purple or will I have to wait for new growth? The shrubs look pretty odd right now with patches of green and purple.

The sun will darken them.

The hort guy at the U. said the right time to prune anything is when you have your pruners in your hand. I tend to agree, when it comes to things you can hand prune. If it was a sapping tree, like a maple, it might be different.

I replaced all seven of mine with knockout roses. If I was going to have to prune something that thorny once a year (or more) it had better deliver something worthwhile.