Mulch 

Soil solarization 

Grass barriers 

Weed pulling 

It may be backbreaking work, but you can get rid of grass in flower beds by pulling out weeds. 

Solarized soil works well for the following reasons: It's a low-cost solution that takes little work.  

First, solarize the soil. It helps control perennial weeds and keeps it moist. 

How to Get Grass Out of Flower Beds