General Culture:
Easily grown in average, dry to medium, well-drained soils in full sun. Appreciates some light afternoon shade in hot summer climates. Too much shade, however, may impede leaf drying and promote the onset of disease. The woolly leaves of this plant tend to trap moisture, and in humid climates such as the St. Louis area, plant leaves are susceptible to attack from rot and leaf spot where too much moisture is present. Plants are generally drought tolerant. Avoid overwatering. If mid-summer foliage decline occurs, pick off damaged leaves as needed. Spreads by creeping stems that root as they go along the ground and can be mildly aggressive in rich soils. Site starter plants 12-18” apart for use as a ground cover. Divide when necessary. Flowers are not particularly showy, and many gardeners prefer to remove the flowering stems as they appear to enhance the ground cover effect.
Noteworthy Characteristics:
Notwithstanding its unusual cottony flowers, ‘Cotton Boll’ is primarily grown by many gardeners for its foliage. Dense rosettes of tongue-shaped leaves (to 4” long) are a woolly gray-green and will form a foliage mat of 4-6” tall. Leaf shape and texture resemble a lamb’s ear, hence the sometimes used common name. Plants are frequently grown as a spreading ground cover. Leaves are evergreen in warm climates, but will depreciate considerably in harsh winters. Erect, small-leaved flowering stems with unusual flowers that resemble cottony balls are the signature of this particular cultivar. Flowering stems appear above the foliage to 10-15” tall.
Problems:
Cultivars of Stachys byzantina tend to rot and develop leaf diseases in humid summer climates. Well-drained soils are essential in order to combat potential rot problems. Even with well-drained soils, some summer die-out may occur where high humidity and/or moisture on foliage is present. ‘Cotton Boll’ reportedly performs better in humid climates that most S. byzantina cultivars.
Uses:
Foliage provides interesting texture and color to the border or rock garden. Effective edger or small area ground cover.
© Missouri Botanical
Garden, 2001-2010
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