I think you don't understand. When ferts build up in the soil, through overferting or just over time, they lock out the ability of the plant to absorb the water and the ferts in it. You see the combination of elements that feed your plant are salts which carry a tiny electric charge that attracts and repels other compounds. The salts grab on to water just like when you eat salty foods, and your plants soil is wet but it can't properly absorb the water or the nutes in it.
Flush, flush, flush, you should give just water every second or third watering anyways to let the plant use up any extras laying around.