Looking great in the garden is the superb fern hybrid, Adiantum x mairisii. We received our first plant in 1993, as a gift from the late fern collector Nancy Swell of Virginia. The similarity in name to the Chinese native Adiantum mariesii, has caused a good bit of confusion in fern collections. This sterile hybrid, however, is a cross of the circumpolar North American native Adiantum capillus-veneris and a yet unknown baby daddy, with the most probable candidated being Adiantum raddianum or Adiantum aethiopicum. It was discovered around 1885 at the UK’s Mairis & Co. Nursery and subsequently named by Chelsea Physic Garden Curator and fern collector Thomas Moore.
Adiantum x mairisii performs like a vigorous clone of southern maidenhair fern but with reportedly better winter hardiness. In five years, we expect see a 3′ patch. We have found this to thrive in both half day sun as well as light, filtered shade in everything from average to moist soils. In our zone 8a climate, the foliage usually remains looking good through the first of the new year, before finally going dormant.
I am really enjoying Adiantum x maresii. Its beautiful, dense foliage looks especially lovely draped over the edge of a rock wall. Our past 2 winters have been especially tough on plants due to occasional single digit temps, as well as week-long stretches below freezing. This fern has not been evergreen for us, but it comes back enthusiastically during the spring and seems unfazed by hot, humid summer months.