removing lawn from around cordylines

Good morning all,
I have 2 cordylines, ones about 12ft the other about 16ft, at the moment they're set into lawn. I need to remove the lawn around them, how would be the best way to do it? Will I kill them if I dig around them too much? :eek:

 

No shouldn't think so, they are deep, deep rooted. :D

 

I agree with pete. grass roots are only surface roots, best leave it where it is. fancy

 

Thanks Pete and Fancy,
It's crucial to my garden plan that the grass has to go. This gardening thing has unleashed a monster and now I have found hundreds of plants I just must have!