The climate in the northeastern United States has always challenged residential gardeners and professional landscapers alike. For most people the chill of fall means pulling out fun collections of sweaters and coats. For the gardener it’s time to shut down the garden. Pulling weeds, shutting down irrigation and covering furnishings are all part and parcel of landscape maintenance. However, a temperature and weather shift associated with climate change has really changed the timetable for many.
While many people still debate climate change and it’s impact, surely we have noticed the effects. A white Christmas is becoming harder and harder to come across. February is dipping lower and lower on the thermometer. We’ve noticed a lot of loss amongst shrubs and perennials that used to be quite hardy and resistant to cold snaps. Colder winters are also compounded when your garden might be on a 22nd story roof deck. Strong winds wick away ambient moisture and temperatures dip even lower than they do at ground level. So your hardiness zone might not be what you think.
Our general rule at J. Mendoza Gardens (a division of blondies treehouse), after the first ten stories, for every ten stories you ascend, your garden steps back a hardiness zone. New York City is considered to be zone 7 city-wide, but when we design for terraces that are 15 or 20 stories high, we’ll pick plants that are more common to a zone 5 to ensure hardiness. One commercial client of ours has their office on the 34th floor. We went with plants that could handle zone 4 hardiness.
For the urban gardener, a Property Manager responsible for a large common roof deck or a hobbyist with a few planters on a terrace, the lesson we’d like to share is that if you’ve lost some perennials, do not replace in kind. Our recommendation is to transition to plants with higher tolerance to the cold.
Suggested Plants (by Genera)
- Eryngium (select species)
- Ligularia (select species)
- Phlox (select species)
Good place to search for plants – “MBG – Plant Finder”
University of Minnesota – “The best plants for 30 tough sites”