Toomany nutes causes a salt build up, yes thats what your seeing around the pot.. whatare you growing in soil. If so, its harder toget rid of nutes from soil, hydro you flush and you can get away with these problems. But with soil, its best to use soil amendments mixed into the soil tosee the plant through a fair amount of its life, relying on plant food to finish them off if you must use plant food. With soil ,you can just top dress with good wormcast and a potting soil mix, this willgive you the extra nutes needed for the flowering period, along with some seaweed solution it works great. You need to look into the organics section for that.
just some potting compost then plant food will also do you proud. Just look into flowering and grow th foods