HI. I don't believe that chlorine builds up in the soil. Chlorine is a gas,and
while it might temporily contaminate your soil after watering,it should
quickly dissapate. what does build up in the soil are salts from the fertilizer
being used.to reduce this build up,first use one quarter the recommended
application of plant food.(This applies to potted plants.) secondly an
occasional warm water flush will help leach out salt build up.