Answer: As I mentioned in my response to your previous question, it's hard to maintain perennials in containers in cold climates, and ferns are no exception. I was a bit discouraging, though; it can be done! It just requires special attention to preparing plants for the cold season. It's best if you can find a way to provide them with at least dappled shade (hanging baskets of trailing annuals, for example). Those that stand sun best are hay-scented fern (Dennstaedia punctilobula) and Japanese Painted (Athyrium niponicum), and sensitive fern (Onoclea sensibilis). Carroll Gardens (444 East Main St., Westminster MD 21157; ph# 800/638-6334) has a wide selection.
Ferns perform best in an acidic (4.5-5.5), woodland-type soil that drains well yet retains moisture well. A good approach, according to Joan Puma's book, "The Complete Urban Gardener" (Harper & Rowe, 1985; ISBN #0-06-091106-9), is to "fill a large container, such as a half whiskey barrel with tow to four inches (depending on the height of the container) of drainage material. Mix together 2 parts top soil, 2 parts peat moss and 1-1/4 parts vermiculite (don't substitute perlite, it doesn't retain moisture as well) and add a 1/4 cup of cottonseed meal for every gallon of mix. Dust the soil with a light coating (1/8") of the superphospahte mixture (composed of equal parts superphosphate, ammonium sulphate and powdered sulphur). Now you've completed your bottom layer of soil. The next lqayer should consist of 2 parts peat moss, 1 part top soil and 1 part vermiculite...add 1/4 cup of cottonseed meal per gallon of mix...if possible add a handful of natural wooldland soil to the mixture. This will introduce the tiny bacteria and fungi that can survive and flourish in such acidic conditions and which woodland plants find so beneficial. Fill your containers within 4" of the top and again add the superphosphate mixture and cultivate lightly. On top of this place a one-inch layer of organic material. Well-rotted leaf mold or humus is preferable, although some peat moss can be substituted." Mulch moderates soil temperatures and moisture, and annual topdressing in spring with rich compost or leaf mold will keep plants happy. I highly recommend Joan Puma's book to you - you'll find her informative and inspriring, I'm sure! Another fine container gardening text for beginners is "Container Gardening for Dummies" by Bill Marken & the Editors of National Gardening Magazine (IDG Books; http://www.dummies.com). Enjoy your garden this season!
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