If you'll mow your bermuda frequently as short as you can, it'll get dense & thrive while the SA will weaken. Your bermuda will dominate in no time -- also keep your watering to a minimum, that'll help too.

You absolutely don't have to put sod down.... most Home Depot clerks are just that.... clerks..... and most don't know what they're talking about.

My 2 cents,

Dan

Usually it is the other way around. I've never heard of augustine taking over bermuda. Try some fertilizer.

St augustine can overtake bermuda under ideal condition... Mow high... water deeply when needed... plant trees...

Floratam st augustine will kick bermuda's butt.

What you could do is establish a "no grass zone", a little strip that is regularly maintained with roundup or even a chemical soil sterilant.

You might also consider putting in some landscaping at the borders of your property. I don't believe neighboring lawns should touch one another.

I've never heard of augustine taking over bermuda.

You're new here. I've been saying that since I got here. If you mow it high and water weekly, you will have a St Augustine lawn. If you mow it low and water weekly, you will have a bermuda lawn with St Aug weeds.

There are two ways for bermuda to win.
1. Stop watering and the St Augustine will die.
2. Pull the St Augustine

I would suggest a concrete barrier between the two yards. There are people who will come in and pour it for you.

This is easy to answer. As stated the best way is just cultural practices of mowing, watering, and feeding. Practice Bermuda grass maintenance and the SA will not stand a chance.

Otherwise if you want quick results, like a week, just use a post emergence herbicide containing 24D and MSMA. A good one is Trimec and made for Bermuda grass. It will not hurt the Bermuda grass, but will kill the Saint Augustine in a hurry.

what if it takes over zenith zoysia!!!

I believe if you water it normally and mow high, St Augustine will march through and take over almost every grassy plant with the exception of some weeds which have slightly coarser blades and also grow tall. Crabgrass can get a hold and hang on toe to toe, but bermuda and other fine bladed grasses seem to have absolutely no chance against St Aug. Here are two pictures of my current back yard. I have not purchased any St Augustine. At first there was a thin line of it surviving against the concrete patio. I nurtured it along and you can see the results after 5 years.

2014

2019

The St Augustine stops at the line about half way between the dog and the bottom of the picture. I mow the weeds low and the St Aug high, so the line is fairly clear. This year it is down to the bottom of the picture and still spreading. The original "lawn" was a mix of dormant bermuda and prairie grasses like buffalo and the ubiquitous King Ranch bluestem.

We are trying to pull up the neighbors' St. Augustine so it won't spread and kill out our zenith zoysia! It is a difficult task.

The grass that has moved into our yard that is, haha!

I have been told by grass specialists that you have to round up it then put a mulched area in so you can see when it moves over and pull it. Otherwise it will not stop!

If you put in a solid barrier at the surface, that would give you something to mow and trim against. It could be a metal barrier but a concrete curb barrier would be easier to deal with. These people used concrete to separate their lawn from the neighbor.