The past two summers, my collection of heucheras was largely chewed down to the veins. These included Paris, Georgia Peach, a small one w/white and green leaves, heucherellas and various others, excepting Caramel which was mostly ignored. These plants are located in varying degrees of partial shade in a tiered flower bed. Other plants in the bed include campanula, Japanese ferns, ajuga and astilbes left untouched. The plant bed is about 6' by 8' and is located between the house and a small stand of oak trees with the ground covered by English ivy and organic debris.
Both years I began treatment with beer in 5 small dishes spread around, suspecting slugs but found no bodies in the dishes after several days. Next, I tried to spray w/insecticidal soap. This was impractical as it is almost impossible to cover the underside of the leaves because they are so close to the ground.
I enjoy the variety of colors, shadings and blossoms of these plants and don't want to give up on them. Can you help?