we only have a half acre of ground and obvously it is not all flower bed, and i don't put down the stuff you talked about to prevent weeds from growing (don't think i could since i don't know where all my perennials will come up half the time) but i am awash in weeds and i don't know how you are keeping your humungous garden weeded, with you being a cripple and all, gabz.
First thing I thought when I got off of the airplane yesterday...WHO LEFT THE SWAMP COOLER ON????!!!!
My prayers are with you. We went through this last spring. It was awful.
coolbreeze called me a little while ago to tell me he is going to be late egtting home from work because of the T'storms knocking out power all over the MD eastern shore. He was in Food Lion over on Kent Island fixing a register when it took a near direct hit and wiped out the self serve register....he said the woman at the machine actually screamed, because she had already scanned nearly a full shopping cart of groceries. From there he had to go to the Holiday Inn, because their server took a hit and then he has to head for one of the TV stations in Salisbury because they took a hit. 
 
I hear you about the weeds.........coolbreeze actually has taken a machete to them. 
 
Even not knowing where all your perennials will come up shouldn't preclude you from using some of the stuff I used this year...........in fact it gives specific instructions on the package for us in existing perennial gardens. I don't remember the name of this stuff, but we got it in WalMart. I think it was $13 for a 3foot by 20foot roll and it is more of a fabric type stuff than a plastic, and has a 10 lifespan to it (so it claims). You start laying it down, and then cut x's in it to go over the existing plants. 
 
Once I've got shade on the kitchen side of the house, about 3:30, I'm going to limp my way out to attack the weeds in the herb garde, and tackle my humongous crop of basil :)
 Any excuse to call the lawnboys, eh? ;-)