- Sensitive Fern-Onoclea Sensibilis Hardy Planting Zones-4-9 Sun or Shade-Part Sun/Full Shade Mature Height-36" Mature Width-48" Bloom Season-Summer (May to August) Gardener Status-Beginner
Sensitive Fern - Onoclea sensibilis
Sensitive ferns aren't the kind that curls up when you touch them. Rather, these exuberant green fronds are sensitive to frost. Despite that sensitivity, the ferns are prolific throughout the lower-Midwest and the Northeastern United States where they are found growing throughout hardiness zones 4 through 8. They only suffer when frosts are early, but they manage to rebound nicely if kept in optimum conditions. The ferns do best in consistently moist soils, to include clay soils. Though they prefer lighter soils, they can tolerate heavy clay and are adaptable to loam soils so long as the soil is kept moist. These bright green, upright ferns display triangular-shaped leaflets with serrated edges. They grow up to four feet high with a three- to four-foot spread. Many gardeners place these ferns in natural gardens and rain gardens. The plants do not bloom, but they bring a pop of spring-green to otherwise purple-dark shade gardens. When conditions are right, sensitive ferns will stay green throughout the summer months but will die back when the weather turns cool. Fortunately, sensitive fern does not attract pests or disease, a rare feature for a moisture-loving plant. In wet areas, replace problem plants with sensitive fern. Gardeners also place containers near water features, koi ponds, and natural streams. Though the plants can be taken indoors to be overwintered in atriums and greenhouses, they are more remarkable and striking when left to overwinter naturally.
Sensitive fern's growth rate is typical for outdoor ferns. After a few growing seasons, they will become a resplendent ground cover. Under extremely wet conditions sensitive fern easily reach their full height, if not more. Under these same conditions, the perennial plant will spread via rhizomes and spores. To slow growth try planting in containers along decks and walkways where the foliage will drift with the breeze.