As Ella and Louis will tell you, Autumn in New York is a romantic time for enjoying a warm cup of tea indoors or the golden hues and colors of the outdoors. With some careful planning and design, it’s possible to bring those two beautiful worlds together with a green roof.
Green roofs (well, more like golden roofs in this blog post) can bring the fall colors normally seen in parks up onto green rooftop gardens. And, with a little bit of proper preparation and maintenance, green roof plants will survive through the winter and flourish again the following spring.
Green Roofs in Autumn
Without further ado, here are a few of our favorite images of the autumnal green roofs that our team has installed in the greater NYC area:
Midtown Manhattan Commercial High-Rise
Brooklyn Botanic Garden
Amagansett (Long Island) Residence
Plant Species Selection
Unlike annual gardens, green roofs are meant to be an perennial system. They can be supplemented with annual plantings and flowers, but for the most part, green roof are designed to last through the winter.While there are a few other tricks we use to ensure a healthy hibernation (see below), a green roof’s ability to survive a winter mostly comes down to plant species selection way back during the design phase. The best plants for any green roof are those that are either native to the area or are readily adaptable to the area. To help with this selection, you can consult a Plant Hardiness Zone Map like this one. (Note: because rooftops tend to be much harsher environments, bump your hardiness zone up a couple of notches for green roof plant selection. For example, a roof located in a 7b zone should go with 6b zone plants.)
Preparing Green Roofs for Winter
For the most part, green roofs should be able to withstand their local climate without much winterizing fuss. This is why sedums are such a staple in green roofs. They are tough, sturdy and don’t require much in the way of water, light, nutrients, or maintenance. A truly sustainable green roof shouldn’t require a lot of extra energy, water, time, money, or other resources to live. Raise ’em right and then kick ’em out to get a job and pay their own rent. 🙂 Let nature take its course!
But there are few extra things you can to help a roof along:
- Install a frost-free hose bib to prevent damage to your pipes
- Shut down exterior irrigation system prior to the first winter freeze in your area
- Blow out the irrigation hoses to make sure no water remains in the lines
- If your roof has lots of flowering perennials, in some cases you may want to put it to bed by cutting down the foliage that’s spent (but you can leave grasses in tact until spring)
- For example, with Echinacea you should cut the foliage down so that it doesn’t get moldy and spread around
And then in the spring…
Once winter retreats and the weather warms, follow these steps. They will help your green roof spring to life again, better than ever:
- Resume irrigation ASAP but only once the freeze cycles are finished, to avoid pipe damage
- Take soil samples and have them analyzed to determine the nutrient balance
- Fertilize based on the findings of the soil analysis to replenish lacking nutrients
- Mow the tips of the sedum plants to spread the cuttings around and encourage more growth and coverage
In New York, we can install a green roof as late as mid-November, and it will come up green in the spring! And then the following year, come October, you’ll have your own golden-orange outdoor carpet like the images above.
If you’d like to learn more about how to ensure green roofs are healthy throughout the colder season, please feel free to reach out.