Onoclea sensibilis was originally given the common name sensitive fern because the fronds are highly sensitive to frost. Sensitive fern is native to both the eastern United States and east Asia.
Sensitive fern is a fern of swampy places and prefers persistently wet conditions.
In shade, Onoclea sensibilis can withstand occasional dry conditions, but in sunnier locations, it must have moisture. In forested woodland with plenty of canopy, I have absolutely seen sensitive fern happy and healthy in areas with average soil moisture.
Ferns such as sensitive fern and cinnamon fern can withstand surprisingly sunny spots in the garden, but continuous moisture at the roots is a must in such situations.
I have grown or attempted to grow ferns in many circumstances, and I find I almost always fail, not immediately but inevitably, if I try to push them outside their limits. It just doesn’t pay to be a risk taker with ferns that demand moisture.
Sensitive fern is hardy zones 4-8. The green fronds can grow to three feet and are sterile..there will be no spores on the backs of these fronds as seen in many other fern species. The fertile fronds are narrow with sporangium that have the appearance of tiny grapes or beads. Sensitive fern is also known as ‘bead fern’ (see photo directly below).
Growing Sensitive Fern (Onoclea sensibilis)
Sensitive ferns grow to three or four feet in height. The most important criteria is adequate moisture. Cool, wet, shady spots are excellent. Should you provide optimal growing conditions, Onoclea sensibilis can become aggressive. It spreads by both rhizomes and spores. Soil should not be stagnant, and Onoclea sensibilis prefers acidic pH.
Sensitive fern is an answer to a question: If you ask yourself ‘what plant would fit into this shady spot with soil that is always wet’, then sensitive fern is the answer. If you have a bog garden, sensitive fern is the answer. If you have average soil moisture in woodland habitat with plenty of shade, sensitive fern is the answer.
On the other hand, if you ask yourself ‘would sensitive fern grow in this spot’ as you survey some location in your garden that is clearly borderline (afternoon sun, dry), choose a different plant.
Should the soil dry out where you end up planting Onoclea sensibilis, the quality of the foliage will diminish as summer rolls on. There are few things in the garden as depressing as leaves curling brown.
Should the fronds of Onoclea sensibilis make it in good health to that first frost for which the fern is named, leave the now-withered fronds on the plant until spring. They will help protect the plant through winter.