I am re-landscaping a house. In the front the shrubs are old, but nice. The problem is there are huge bunches of iris. The customer wants these thinned out, but it seems they all will have to be dug up and re-plant about 1/4 of them. Would using a tiller to dig them up be a bad idea? I tried digging some up today, but there are so many it will take 2 days to do it. Any help will be appreciated. Thanks in advance.