All this talk about rooftop gardening makes me want to climb up onto my own roof to get started. That’s right! Believe it or not, my roof is naked; bare membrane all the way. How could this be? It’s simple. I lived on a 3/4 acre lot in peri-urban Philadelphia neighborhood for several years, with a sloped roof and backyard garden. A few months back I migrated closer to Center City, and now rent an apartment with a shiny new roof that’s flat as a pancake. Tabula rasa.
How will I turn this blank slate into a garden? Here are my top 7 rooftop considerations:
1| Access: Getting up to the roof is a cinch thanks to my apartment’s headhouse, or pilot house. Local building codes require that I access my roof regularly through this rooftop vestibule and door that connects to a staircase below, so I’m in the clear. I’ll be thankful for the staircase when I’m hauling compost and veggies up to and down from the roof. I may even be able to store a few small tools – hoe, blunt-nosed spade, hand shears – at the top of the stairs.
2| Weight: Veggies and herbs grown in wet soil can be heavy. When designing my garden layout on paper (after all, I am a landscape architect), I’ll be conscious of where the heaviest loads will be located. My brownstone is strongest along the parapet and where my building meets the neighbor’s building, so this is where I’ll site the heavier planters.
3| Edge condition: Strangely, no knee walls exist between my roof and the neighbors’. I’ll need to make sure that my guests and I don’t walk off my property or take a tumble, which technically means installing a guardrail. This infrastructure exceeds my budget, so I’ll likely get creative with raised planters secured to one another along these compromised edges.
4| Penetrations: Thank goodness this photo (left) shows my neighbor’s roof and not mine! This field of pipe penetrations and mechanical units would create a “Swiss cheese” roof garden as containers dodge the rooftop clutter. My roof contains only a few penetrations that are luckily grouped together. I’ll keep my garden away from this potentially leak-prone area.
5| Membrane protection: Protecting the roof’s waterproofing membrane from punctures and foot traffic wear and tear is essential in maintaining a dry apartment down below. I’m considering laying thick rubber walk pads over the roof with addition protection under the planters. A 30 mil polyethelene sheet would not only protect the membrane from roots penetrating the waterproofing, but it would also add a thin layer of protection between my spade and the roof.
6| Water access: Sadly there is no hose bib on my roof, and I don’t have the authority to hire a plumber to install one. My garden will be watered the old fashioned way: with a watering can. I’ll keep this added effort in mind when deciding how big the garden will be.
7| My landlord: As renters, my boyfriend and I must work within the bounds of our landlord’s wishes. Interestingly, when our landlord first showed us the apartment he took us onto the roof and said, “You can grow vegetables up here if you want.” He had no idea who he was talking to. Neither my boyfriend nor I had mentioned my expertise or book, and instead just smirked at one another. “Okay, we might try that.” And with that, we enjoy our skyline view from our naked roof, and will enjoy it that much more once it’s planted with vegetables this spring.