Certified GKH Gardening Expert
Since it's a good idea to keep weeds down within raspberry patches, growing monkey grass should help, as this groundcover will eventually fill in empty areas. I do not think it will choke out your raspberry plants. Monkey grass is seldom an invasive problem, provided you have the clumping variety. However, I would make sure to keep the raspberry plants pruned as these can get quite large and unkempt in appearance without annual pruning.