Due to its slow growth, Bahia grass does not generally take over weeds. In fact, the opposite can be true. Young Bahia grass is susceptible to being taken over by weeds. 

Likewise, in the cool season, Bahia grass goes into a dormant state that can allow weeds that thrive in early spring to get the upper hand. If you want to prevent weeds from taking over your yard, remove them by hand or apply a Bahia grass-friendly pre-emergent herbicide to your lawn before weeds have a chance to appear.

Glyphosate and other non-selective herbicides can kill orchard grass, but they will also kill the surrounding plants. Also, not all areas allow the use of glyphosate due to its environmental impact—which the EPA describes as a "potential risk to terrestrial and aquatic plants and birds, and low toxicity to honeybees." Consider mechanical removal to target the plants specifically.

Poison oak is similar to poison ivy in that it's in the same family of plants. Poison oak is identifiable by its rounded-off leaves and hairy leaf texture. Tree-climbing varieties live primarily in western states while low-growing poison oak bushes occupy the eastern states. Treat poison oak like poison ivy to get rid of it permanently.

The best way to prevent weeds is to use polymeric sand, which hardens and blocks weed growth when activated with water. If you're using regular sand, you'll need to refill and compact it more often. Keeping the surface clean and free of debris can also help prevent weed seeds from settling in the joints.