i have 4 ROS in same soil and sun

2 bloom , although less than they did in early june

1 bloomed copiously late spring but now has buds that won't open

1 bloomed copioulsy late spring but has had no buds for last 3 weeks

squirrel were eating flowers so i spray castor oil

i also fed them hibiscus slow release 15-30 -15 granules

what gives