They don't like a lot of salt spray either.

I live in the Tampa Bay area of Florida. We have a nematode problem and really sandy soil, but lots of people grow hibiscus everywhere around here. I haven't tried it myself though.

You won't find a nemacide anywhere, I've tried! They quit making any for the home gardener, only ones that can get anything have to have a licence. Unless you know someone of course, but then you should be very cautious cuz they are very strong an can harm the enviroment. I'm trying the solarization method now for them. Won't know if it worked till fall when I pull the summer plantings.

Shrimp shells are suppose to be good for nematodes. I was always told to run them through a blender and mix into the soil. Never tried it but then I have never had a need. Wish you luck and good fortune solving your problem.