As donmajicjuan's post explains, the landlord has very limited access rights once he has rented the property. He must give notice and he must have a legitimate reason. He is not allowed to enter the property at will.
However, if you are growing illegaly and you have an intrusive landlord, this doesn't help. If he does enter the apt and discover your grow he may be breaking the law but if he goes to the cops, I think that's all they need for a search warrant.
Yeah, I think that's about right.
Your landlord may not have the legal right to enter your apt when you're not there, but frankly, what are you going to do about it?
Complain to the cops?
Try to sue him?
If you really have a nosy landlord, you've got limited options:
a. Stop growing.
b. Move somewhere else.
Incidentally, while you *might* be able to find a landlord sympathetic to your growing, unless you're living in hippie-land like CA or Oregon, I wouldn't count on it.
In most of the USA growing pot is still illegal under State law and worse, in some jurisdictions property used in the commission of drug offenses can be seized WITHOUT DUE PROCESS.
In other words, in some jurisdictions a landlord could lose their property if a tenant is caught growing pot on it. . .even if they had no idea it was happening.
So even if a landlord doesn't really care if you smoke or grow pot, he may have pretty good reason not to want it happening on his property!