I have never frostseeded, but I have drilled it and all I can say is it is all about getting the seed to germinate and controlling competition. If you can;t control competition your results are going to be poor. Cool season grasses in particular are going to become active well before the switch can germinate and thus shade out the switchgrass. I had to spray and mow mine in the dead of summer to give the switch a fighting chance to get established. Once you get it established your fine, but getting to that point can be a real challenge. If you want to plant this fence row I would suggest taking this year and kill off all the weeds and the like - you may be able to retain the shrubs, but any exisiting weeds and grasses will need to go. Then you can frost seed or plant your switch. Your still going ot have to control other weeds that will pop up in the establishment year as well. It can be a decent amount of work that first year. NWSG are not a toss the seed and walk away sort of thing.....even with switch.