Penstemon · Perennial
Slugs and snails: Use physical barriers like copper tape or apply iron phosphate pellets around the base.
Aphids: Squash by hand, blast off with water, or use insecticidal soap for severe infestations.
Powdery mildew: Improve air circulation and avoid wetting foliage; treat with a sulphur-based fungicide if necessary.
Grey mould (Botrytis): Remove affected plant parts immediately and ensure good air circulation to reduce humidity.
Leaf and bud eelworms: Dig up and destroy infected plants; avoid replanting penstemons in the same soil.