Very bad white staining on Acer leaves
Vendée, Western France
Before you put down any stones, make sure you add a layer of well-rotted manure around each tree a sthey need food as well as water but, as indicated above, keep it a couple of inches away from the trunks.
Then lay your weed suppressing fabric and lay stones or gravel on that so no light can get to the soil below. I suspect white stones will be very stark so consider chipped slate or stones in a colour which is sympathetic to your house walls or other hard landscaping in your garden.
"We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
so how so how often should I water during winter months ?
Central Norfolk UK
I don’t water anything outside in the winter ... hardly anything is actively growing.
“I am not lost, for I know where I am. But however, where I am may be lost.”
Winnie the Pooh