Talking ferns

The Greenhouse Management team recently spoke to Dr. Raymond Kessler, a professor at the University of Auburn in Mobile County Alabama, about his work with ferns and some of the trends he sees developing with the plant.
 

Greenhouse Management: First, what are some of the major varieties of ferns?

Raymond Kessler: Hardy ferns, perennial ferns, are ones that are more or less grown in a nursery setting in one gallon containers or quarts or something like that. Tropical ferns, like Boston ferns or European table ferns, are produced in a greenhouse setting. In the South, we grow a lot of Boston fern hanging baskets. I just wonder what black hole those things disappear into at the market. We have specialty growers and that’s all they do.
 

GM: Do you have any tips for cultivation? How are growers doing it near you?

RK: Production of ferns in Mobile county Alabama (where Kessler is located) is going to be different than in other areas. But here in Mobile county:

• They’ll bring in liners from some place, most typically Florida.
• They’ll pot them up in 4-inch pots for six to eight weeks, just to fill it out.
• Then in the fall, they’ll put one 4-inch pot in a 10-inch basket.
• They more or less, grow them while it’s warm but to save on heat, they’ll cut it down to the mid-40s F.
• They’ll hold them and then, in the spring, they’ll bring the heat up some to finish them for late April, early May.
   

That production style is a little bit different because of the temperatures here. I’d say that for the vast majority of the East Coast though, it’s generally a fall planting of a liner and then grow through the wintertime and target that spring market. Some ferns are a lot faster. The time frame is a lot shorter. They’ll bring them in that spring and finish them that same spring. It can be variety dependent.
 

GM: What are some common diseases and pests of ferns?

RK: There aren’t many and they don’t appear very often. Some of them are common greenhouse pests like fungus gnats and mealy bugs. Under really hot conditions you might attract spider mites. I wouldn’t say anything is super specific to ferns. Pythium root rot can be a problem if you over water.

If you take a small Boston fern liner and put it in a 10-inch pot, it’s very difficult to water correctly. That’s why many growers go to a 4-inch pot first and establish a larger plant. So they’re bringing in something like a 72 plug flat and transplanting to a four inch and getting some good size on it, growing it there for six to eight weeks and then transplanting that 4-inch into a 10-inch pot.

If you put a 72 directly into a ten inch pot, it’s very easy to overwater.
 

GM: Have you noticed a trend in fern popularity?

RK: Fern popularity is steady. Perennial ferns seem to be on a slight upswing.

When I was growing up, a lot of people would keep Boston ferns in big pots on their front porches. And they used them in weddings and funerals, and stuff like that. In the SouthEast it’s a long tradition but I’m not sure where it originated.

I remember growing up in a Southern town and some of the homes would have shady porches. And on the porches would be these enormous terra cota clay pots of Boston ferns. It’s kind of a Southern tradition.

I do a lot of work with the Boston fern, which is really a selected cultivar from the Florida sword fern which grows in Southern Florida. It’s a native plant. It was selected by a grower in the late 19th century in Boston, Mass. There are lots of cultivars out there but there are maybe a half dozen that are widely grown within the Boston fern line.
 

Three questions with John Mickel

Greenhouse Management also spoke with John Mickel, a senior curator emeritus at the New York Botanical Garden, about ferns. Mickel’s New York Botanical Garden page notes that he’s been studying Mexican floristics for 40 years. However, his other passion has been the history and development of ferns. He was the founder and only secretary for the New York Fern Society and the founder of the American Fern Society’s bulletin, the Fiddlehead Forum.
 

GM: How long have cold hardy ferns been around?

John Mickel: Tough to say but over a hundred million years. If we’re talking how long they’ve been in cultivation, I would say since the Victorian fern craze in the late 1800s in England.
 

GM: What is the biggest misconception about ferns?

JM: I think the biggest misconception is that ferns are very sensitive and difficult to grow. But consumers prefer cold hardy ferns, I believe, because they are relatively easy to grow in light shade, they don’t require much care and they are deer-resistant.
 

GM: How do cold hardy ferns differ from other ferns?

JM: Cold hardy ferns differ from other ferns only in their tolerance of cold weather. They occur naturally in temperate regions of the world — northern North America, northern Europe, China, Japan, and even high-elevation tropical America (e.g., Dryopteris pseudofilix-mas, Mexican male fern, from Oaxaca, Mexico, ca. 9000 ft elevation).