You need to figure out what plant(s) makes you sneeze (skin test is an option).

Then you'll need to wear a face mask every time you get close to that plant (it has to be suitable for filtering small pollen particles).

If you don't want to use a mask, you'll need to take antihistamines but they may be too weak and you'll sneeze anyways or they may be too strong and you'll be sleepy.

If someone has a better option I am all ears, sadly it seems that medical knowledge is very very limited, so there is currently no cure to allergies. I will be very happy to be proven wrong!