That is a tough question to answer because if you are having problem with getting anything else to germinate its probably a bigger problem then just gophers. The plants you describe (lavender, catmint, marigolds, and rosemary) should all help in making the garden less appealing to rodents so that is a step in the right direction. Activity around the garden on a regular basis will also deter pests since they don't like all the commotion, especially if people bring their dogs with them :)

Its a little hard to make out from the question but are you having problem getting plants started, this is how I interpreted the question but I'm not exactly clear. When transplanting from a greenhouse or your own starts, set them out on a cloudy afternoon or two before putting them in the ground, so they get use to the direct sunshine. Plant in the evening or a cloudy afternoon too so they get more time in the ground and out of direct sun to help get those roots established. Mulch so that the soil remains cool so the roots can grow and the plant doesn't get heat stressed. As for seeds, you can soak those listed the starting the night before to improve germination. Again, they will need plenty of water moving forward since rain is becoming more hit and miss this time of year.

Then the next question I need to ask is whether the seeds won't germinate and transplants do ok or if transplants die in the soil once they are transplanted? If transplants are going in the ground, and they are watered daily, and still all die? Then there could be a herbicide in the soil...and if that is the case there isn't anything that can be done until it naturally degrades. If you think this is the case (that someone before you used a systemic herbicide or brought in contaminated mulch) I recommend you contact the Parks and Rec department.

https://extension.usu.edu/planthealth/ipm/ornamental-pest-guide/vertebrates/pocket-gophers

Otherwise good luck with your garden!