Creating Roof Gardens

Roof gardens can be created in even a small amount of rooftop space, but container gardening on roofs presents a definite set of challenges (although the end result can be well worth the effort!!) More and more people who live in the cities are creating their own urban gardens, or green roofs, as they are commonly called. They allow people who by choice or necessity live in urban areas to experience the creativity of gardening, and even better, have a living, growing refuge to go to at the end of the day! Urban gardening on rooftops can give you the both of best worlds, as long as you keep several practical considerations in mind.

While small, this rooftop garden has been filled to capacity with
an abundance of beautiful flowers and greenery! Green roofs have
become a welcome feature on rooftops of all shapes and sizes,
from resorts and hotels to apartment buildings.

© Ifeelstock |

On the larger side of the scale, this incredible resort in Singapore
features a modern roof garden complete with a swimming pool
on it’s cantilevered platform.

© Ximagination |

Whether you use planters, pots, or build yourself some flower boxes, you must use a container of some sort to when you are creating a roof garden. This of course means that those containers, and the soil, plants, and tools you use must be raised up to the roofs surface. Keep this in mind when you consider the size of the roof gardens you want to create. If you’re having to climb a set of stairs, or (even harder!) some kind of ladder, you’ll probably want to keep your garden small. Even using an elevator, carrying materials to your rooftop can be a lot of work, but if you’re up to it, (or can afford to have it done!), a rooftop oasis full of beautiful flowers and foliage will reward you with a place of peace and serenity above the busy world below.

If you have limited or awkward access to your rooftop, you may want to
keep your roof garden on the small side, as this gardener has done by
using railing planter boxes and smaller pots at the railing’s base.

© Graça Victoria -

This rooftop has plenty of room, and since the floor has been finished with ceramic tile, it probably has elevator access. It also appears to have been fitted with a watering system, as indicated by the pipes at the base of the round containers. Regardless of whether it is a private residence or a hotel, it took a great deal of work to build, but on nice, sunny days this urban garden would be a wonderful place to read a book and enjoy a drink!

© Kenneth Summers -

Before you start, find the closest source of water. If you’re lucky enough to have a spigot on the rooftop, the problem is taken care of! But if not, think again! How many trips with a watering can are you willing to make up and down at least every two to three days? (a good investment to consider might be a large rain barrel!)

Seeing that this gardener has more than a couple of plants to water, if no spigot is available she’s going to have her work cut out for her! Multiple trips with a watering can can be time consuming and physically challenging, (unless you consider it a part of your daily exercise program!)

© Harald Jahn -

One of the most important considerations for rooftop container gardens is the size and weight of the containers that you will use. Most rooftops are sturdily built and will bear the weight of the majority of your containers, but its a good idea to check with an architect or builder and/or have a structural survey done to determine how much weight the roof can support and to identify any weak spots.

Planters this large would probably need to be lifted onto a building’s rooftop by a crane. Roof gardens that are specially built on buildings such as hotels and other commercial buildings have the weight of the containers planned
out in advance, and that’s why you can often find such beautiful and large garden features, including fountains and pools, on them.

© Hansenn |

Larger containers, (particularly over-sized pots) can become very heavy when filled with dirt and plants, especially when they are watered. For this reason it’s a good idea to place these heavier containers near the edges of the rooftop space, where the floor has greater support.

Placing the containers around the edges of this small rooftop garden not only takes advantage of the additional stuctural support, but also allows for more available open space in it’s center. Notice that the owners are lucky to have a hose that is connected to the side of the building by the door.

© Stanko07 |

If your green roof is structurally sound towards it’s middle, you can place your containers in more creative arrangements, using them to divide spaces and placing pots at different levels to create interest. You can lighten large pots and planters by using either lightweight containers or filling heavier containers partway with fillers. (If you do this, be sure to not plant them with a taller plant, as it will make it top heavy and susceptible to toppling over, especially on windy days).

Rooftop gardens are subject to extreme weather conditions, which definitely should dictate which plants you use in your pots and planters. The exposure to the elements is harsher on rooftops than on the ground, as there is nothing to shelter them from wicked winds, driving rains, or the hot glare of the mid-summer sun. If there is any structural protection on the roof, use them to help support and protect your plants, and if possible (or if you’re handy), building a partition, screen, or some other kind of windbreak will help to shield them.

The screening built onto the railings of this roof garden not only helps to
 block some of the force of the elements, but they also support the plants
and add privacy and intimacy to it.

© Alisonh29 |

If there is a wall or ledge on your rooftop, placing your containers at the base of them may provide a bit of protection to the pots at least, and if you plant them with trees and/or shrubs, the plants themselves will act as a screen and will help to improve conditions a bit. Not only will they eliminate some of the winds force, (especially if several containers are placed close together), they will also provide a bit of shade to block out some of the sun’s heat.

If you look closely, you’ll see how a frame has been built and covered with some kind of support that allows the plants to crawl up the side of it and spread horizontally across it, creating a shady area beneath it.

© Andre Nantel |

Trees and shrubs can easily be grown in larger containers, as long as they are watered and fertilized regularly. Choose specimens that will not grow too quickly, as they will soon outgrow their containers.

These containers are a good size for these small trees, giving them
plenty of stability for the plant to grow upwards and plenty of room
for the roots to spread downwards!

© Frank11 |

Buy plants that will not grow more than ten feet tall, as taller specimens may easily be blown over, unless the container is anchored well. (Again, keep the weight of the container in mind, and position it where it will have the most structural support.) Use containers for trees that are at least thirty-six inches wide, are deep, and have a sturdy base. For all your plants, try to stay away from tall, narrow containers, unless they are well anchored.

Depending on how big their containers are, these trees are just about the maximum height you'd want to use on roof gardens.

© June Cairns |

Surround your trees and bushes with plants with strong, woody stems, such as roses or lavender, or choose tough plants that have flexible or wiry stems. Plants with long and/or broad leaves can be easily shredded in high winds, and in some varieties the leaves will become brown if subjected to too much wind, regardless to how much they are watered. Use containers made out of materials that help to retain moisture as much as possible, such as plastic, resins, or glazed ceramics.

These flowering heliconia shrubs have tough stems and slender leaves,
which are flexible enough to withstand the strong winds they’re sure
to encounter on this redwood covered rooftop.

© Joanne Zh |

Medium height flowers and low growing plants have an easier time putting up with the wind, as long as they don’t have easily breakable stems. Choose plants that are sun and drought tolerant, especially if your roof garden has little or no available shade! Drought resistant plants will tolerate both windy and sunny conditions (although they don’t care for being overly wet). They work well because the soil in the containers of most urban gardens have a tendency to dry out quickly, again due to the sometimes excessive wind and heat. Plants that are not drought tolerant may need to be watered several times during the day on a hot, windy summer day!

These collection of low growing plants and flowers look lovely
against the white walls of this beautiful rooftop!

© Robert Lerich |

Placing containers of medium and low growing plants in groups and at different levels against your taller shrubs and trees will not only help to shield you from the elements, but will also help to block the view of your garden from surrounding, taller buildings and adjacent rooftops, providing privacy and intimacy to your rooftop garden oasis, and providing a safety barrier too! In effect, you will be building a wall made of containers and plants!

All the sides of this lovely roof garden have large bushes planted along them, creating areas of shade, blocking some of the wind, and making a natural privacy screen. Notice the bars placed along the width of the open spaces, which easily could be covered for additional screening!

© cronopio -

Creating roof gardens is definitely a labor of love, and if you plan on doing the work yourself, keep these considerations in mind. But also remember that even a small rooftop garden is well worth the effort...
a grouping of beautiful flowering pots placed next to a garden chair under a garden umbrella can be as much of an oasis as large urban garden at the end of the day, if it's your space and helps you to forget about the weight of the world below!

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