Living in the city has many upsides, but unfortunately forces us to give up the suburban pleasure of maintaining a garden and owning our own personal patch of green space. Or does it? Rooftop gardening has taken off in a major way across New York City, and, with some planning and preparation, you too can cultivate the garden of your dreams far above the bustling traffic below.
Before You Get Your Hands Dirty
Your first order of business should be to check in with your building to ensure that you have the right to access and grow plants on your roof. The last thing you want is to wake up one morning and discover that your beloved garden has been tossed out due to a misunderstanding over your rights to access the roof. During this conversation, it’s also worthwhile to check in and determine the weight-bearing capabilities of your building’s roof. Rooftop gardens can get heavy, and it’s useful to know ahead of time how much weight your building can accommodate. Finally, ask to see if there are any upcoming repairs due on the roof so that you can plan to relocate your plants if needed.
You should also take the time to evaluate the growing conditions your roof offers. Try stopping by at different times of day and taking note of which areas receive full sun (six or more hours of direct light a day) and which areas are more shaded. This will help you to determine which plants will fare best on your roof later on down the line. Temperature is another factor worth considering—dark rooftops tend to absorb a lot more heat than ones that have been painted to be pale or reflective. Make note of wind levels and investigate to see if your building has any natural windbreaks, such as walls, railings, or a stairwell structure, that you may be able to take advantage of.
Finally, you’ll need to assess what kind of access to water you’ll have on your roof. Some rooftops come with a spigot and hose, which makes watering a breeze and means that your growing options are pretty much unlimited. If your rooftop does not have this amenity, you can consider installing a rain barrel on your roof to collect rainwater runoff that you can use. Otherwise, you may simply have to make use of whatever water you can carry up from your apartment in a watering can.
Laying the Foundations
Before the planting itself begins, you’ll need to think about exactly what kind of garden you want. Are you looking for a chic spot to host cocktail hour? Your own miniature farmstead? An untamed green escape from the concrete jungle? Each is possible, but each comes with its considerations.
Since you won’t be planting directly in the ground, you’ll need to get your hands on some planting containers. If you’re interested in establishing a specific aesthetic for your roof garden, there are plenty of planter styles available to choose from. You can explore using raised beds at various levels to add visual interest to the space. It’s important to make sure your containers are not too heavy for your roof to bear but are sturdy enough that they won’t topple over, especially if they’ll be holding tall plants or exposed to a lot of wind.
It’s generally a good idea to invest in some pot feet for your planters. By elevating your plant containers a few centimeters above roof level, they allow for better drainage and improved air circulation around your plant’s roots and also protect the surface of your roof from being damaged by water buildup.
Since you’ll be planting in containers rather than directly in the earth, it’s best to go with potting soil rather than garden soil. For rooftops where weight is a particular concern, there are even some lightweight varieties of potting soil available. Potted plants require more frequent fertilization than earthen beds, so if you have enough room on your roof, it may be worth investing in a compost bin and learning to generate your own compost!
Depending on how many plants you aim to grow and how you aim to use your garden, it may be important to leave room for furniture in your ground plan. If you make space for a table and chairs, your lush green roof can be the perfect setting for a rooftop soirée or a dinner made with homegrown produce—or, if you feel like getting fancy, you could even consider installing a hammock or outdoor bar.
Flexing Your Green Thumb
There are no strict guidelines about which plants grow best on rooftops. Each roof is its unique geo-climatic zone, and the height and positioning of your specific building will impact growing conditions based on sun exposure, wind levels, temperature, and other environmental factors. As such, determining which plants thrive on your particular roof may require some experimentation.
One good rule of thumb is that plants that grow naturally on mountainsides tend to do well on rooftops, especially the higher up you get. After all, the elevation and wind levels aren’t too dissimilar! If your roof gets a lot of sunlight, drought-tolerant plants like cacti or succulents may be a good option; if your roof is largely kept in shadow by the surrounding buildings, you’re better off sticking with shade-loving plants like Hosta or lungwort. Bear in mind that weather conditions will become more severe as the seasons change, and it may be necessary to have some of your more sensitive plants overwinter indoors.
Those who are big on home cooking should consider planting lots of fruits, veggies, and herbs that they can bring downstairs into the kitchen. Flower-lovers can plant blossoms to their heart’s content—but they should be aware that long-stemmed flowers are susceptible to wind damage and that they may be better off sticking with low-growing flowers like thyme, violets, or lily of the valley.
Tall, sturdy plants like trees or bamboo can be a great way to maximize the vertical growing space offered by your roof and can also help block unsightly rooftop views or even give you some privacy from your neighbors. Climbing vines such as clematis are also great for this purpose and can even be used to separate a dining or relaxation area from the rest of the garden if grown using a trellis.
Ultimately, your garden can be whatever you’d like it to be, and labor and price point should be no barrier to creating your rooftop paradise. You don’t necessarily need designer planters and the rarest bulbs—cobbling together a garden with a couple of lettuce plants and a repurposed kiddie pool can be just as rewarding an experience.