Rent increase notice if lease already signed?

[Maria M.]

Hello, I have a question about the procedure for rent increase. Since l had to increase rent for a tenant, l first talked about it via phone and text message (it’s very difficult to communicate with them via email), then signed the new lease.
My question is, if they already signed a lease with the new amount stated, do I still need to notify them via certified mail? I am in Florida, which requires written notice for rent increase. The lease is a standard lease and doesn’t mention anything about how notices have to be delivered. Thank you!