I have used this for many years, it gets the job done 100% every year. Spraying is typically January and February, effective for 8 months, by then the grasses and weeds in our region have stopped production, and we are good until the next January.
I was looking for someway to control winter annuals such as henbit and chickweed in flower borders and in the rows of crape myrtles that surround my property; as well as under the electric fence around my garden and orchard. A weed killer alone did not do the job, these seedling continue to germinate from August until a hard freeze. When I learned about Surflan and that it could be mixed and sprayed with roundup, I decided to give it a try. I sprayed a mixture of roundup and surflan in the same tank, saving time and effect of not having to put down a weed killer and then a pre-emergent. I have not noticed any new weed seedlings germinating since using the product. I have enjoyed seeing weed free areas around my borders and along the rows of crape myrtles, two double rows of 175 shrubs and tree types. Also, there are no weeds under the electic fence. The real test will come in the spring when chick weed and henbit take over all bare areas of my property. I used the higher concentration of Surflan to extend.
I did a test plot with this since it's the first time I used it, and it has kept the weeds out good the other plots I've been spending my weekends pulling and spraying