Our products are designed for water. The fertilizer will stay on the yard regardless of watering or rain. The weed control, on the other hand, may be affected. If you get heavy rain after a weed control application, keep an eye on your weeds and if you don’t see them dying off after 7-10 days, give us a call and with our Green Oasis Promise Guarantee, we will come out and reapply for no charge.