Sensitive Fern

sensitive fern onoclea sensibilis wisconsin native ferns perennial bead ftimg

Sensitive Fern

Onoclea sensibilis

Description & Overview

Bearing its name from its sensitivity to frost and drought, Sensitive Fern capitalizes on wet and humid environments. The large textured leaves create a grand green expanse to an under-story or the north side of a foundation. Sensitive Fern is the perfect addition to a shady native garden, along the roadside or bog.

Core Characteristics

Mature Height: 1-2ft
Mature Spread: 1.5-2ft
Growth Rate: Perennial
Growth Form: Clump-forming
Light Requirements: Partial Shade to Full Shade
Site Requirements: Moist, well-drained, prefers rich soil with plenty of organic matter
Flower: No flower, reproduces by spores
Bloom Period: Releases spores summer to fall
Foliage: Soft green, coarse-textured, pinnatifid with triangular leaflets. Fertile fronds are stiff and tall and will brown late summer, then carry bead-like spores through winter.
Fall Color: Not Significant
Fruit Notes: Reproduces by Spores

Suggested Uses:

Sensitive Fern’s fan-shaped leaves create a perfect flowing mass for a wet-shady understory, it does well in swampy areas, along rivers, or in bogs, to name a few options. The light, soft-green foliage makes it a great companion to flowering shade plants. Sensitive Fern, as its name suggests, has strict siting requirements. It cannot withstand drought or frost. Therefore, the planting location should be a sheltered location, void of prevailing winds and direct sunlight. It is crucial to check soil moisture during the dry months of summer to ensure the fern is receiving enough water.

Sensitive Fern will colonize a location; however, this happens slower than most other ferns. The root system is comprised of a hefty rhizome with numerous fibrous roots. Although, not necessary, it may be beneficial plant in a visible location.

Throughout winter, bead-like spores cover the showy fertile fronds awaiting spring. And as a sure sign of winters end, observe pale red fiddleheads emerging in Spring. Cut fronds can also be a wonderful accent to a floral or container arrangement.

sensitive fern onoclea sensibilis wisconsin native ferns at johnson's nursery in menomonee falls

Salable size #1 container. Picture taken June 1.

Wildlife Value:

Sensitive Fern has a surprisingly significant impact on native and non-native wildlife. Since this fern is only tolerant of specific humid sites, it attracts many animals with the same opinion. Salamanders and frogs will take shelter underneath the foliage and in the cool soil. Above the foliage, birds will take advantage of the fertile fronds still standing with a great snack of spores.

Some aphids and moth larvae will suck on the juices of the fern, but it poses no health concerns. Sensitive Fern is poisonous to horses if eaten in large amounts. Deer like to nibble on the infertile fronds, but usually not to a debilitating extent.

Maintenance Tips:

Sensitive Fern doesn’t require much maintenance in optimal locations. Over time, the fern can begin to get crowded, in which case, space it out by separating the rhizomes in the spring and re-planting. This can be a good routine to execute every couple of years to prevent any unwanted disease from taking advantage of the dense, humid environment. Once the first frost comes and the fronds wilt, you may cut and dispose of them. Or, simply do nothing – let them drop and become part of the fern-understory and an addition to the organic matter in the soil. This is very subjective and can depend greatly on the visibility of the ferns in you landscape. The upright fronds should be left over winter, so the spores release and afford birds a winter snack.

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Onoclea sensibilis has no major pest or disease problems. Many common problems develop overtime because of the consistently moist environment. In which case, thinning the fern out can provide more air flow. The vibrant green foliage may begin to fade during the hot months of the summer; this is normal seeing as though this fern is sensitive to any amount of drought.

Leaf Lore:

The Sensitive Fern is monotypic, meaning it is the only species in the genus Onoclea. Another name for the Senitive Fern is ‘Bead Fern’, which originates from the appearance of the bead-like spores that appear on the fertile fronds over winter.

Companion Plants:

Many other native plants can go along with Onoclea sensibilis; native plants that do well in “rain garden conditions” are a perfect fit. This includes prospects such as: Milkweed (Asclepias spp.), Asters (Aster spp.), Purple Prairie Clover (Dalea purpureum), Purple Coneflower (Echinacea pallida), Joe-Pye Weed (Eupatorium spp.), Spiderwort (Tradescantia spp.) and many other perennials. A couple other larger shrubs that could be paired with the Sensitive Fern are: Dogwoods (Cornus spp), Ninebark (Physocarpus opulifolius), Common Snowberry (Symphoricarpos albus) and Viburnums (Viburnum spp.). There are many plants that are tolerant of the same conditions as the Sensitive Fern and that would look great when paired with the delicate fronds and early emerging color to the landscape.

Sensitive Fern Onoclea sensibilis benchcard