It's hard not to find rooftops in metropolitan areas speckled with gardens. That's because in an urban setting, space is limited and gardens are becoming the norm for recreational hot spots in the hustle-and-bustle scenes. A roof garden is an ideal place to get away from everyday reality and enjoy greenery and tranquility.

In addition tothe idea of a getaway, it serves many purposes. It allows building owners to save energy, reduce wastewater, and protect a building's roof. In this article, you will learn more about what roof gardening is, the purposes of a roof garden, and how to set one up.

What Is a Roof Garden?

Roof garden with boxes in garden bordering

Image via: Flickr

A roof garden is, as the term implies, a garden that grows on the rooftop of a building. The gardens are human-made and can usually be found on top of industrial, commercial, or residential building structures. The reason people build them is usually to have a living, green recreational area for either the public or private enjoyment.

The concept of a roof garden can be split into two categories: extensive and intensive. An extensive roof garden is a garden that requires little maintenance and exists typically on top of family residential buildings. An intensive rooftop garden is a garden that requires more upkeep usually because of the plant varieties that are grown; they find their homes on top of commercial buildings. 

The Significance of a Roof Garden

Besides the visual and reverie pleasures a rooftop garden can offer you, there are many benefits to reap from having a green roof. The main advantages are energy savings, structural support, and stormwater management.

Roof Gardens Save Energy

Typically, urban areas are hotter than suburban and rural areas. This is because of all the asphalt, concrete, and various man-made materials that absorb solar radiation through the process of conduction. This results in much hotter temperatures in the summer. This spike in heat places pressures on energy bills for many buildings.

A rooftop garden attenuates the energy bills by a cooling effect via the shade it produces on the concrete of a building; it can reduce the rooftop temperature of commercial buildings by upwards to 80 degrees Fahrenheit on a sunny day. It can also reduce the average daily energy demand of an air-conditioning system and save over 75 percent in costs.

Garden Roofs Protect the Physical Structure of a Building

Roof gardens keep the actual rooftop of a building in equilibria. Without a rooftop garden, when exposed to cooler temperatures, roofs tend to shrink; when exposed to hotter temperatures, they tend to expand. This state of constant fluctuation can shorten the lifespan of a roof. The exposure that bare roofs of buildings, far above the Earth's surface, experience daily changes in temperatures around 83 degrees Fahrenheit. Adding a rooftop garden can add decades of vitality to a roof.

Roof Gardens Manage Stormwater

Another benefit of a roof garden is its ability to manage stormwater. One research study found that roof gardens reduce the amount of runoff from stormwater by about 75 percent and delayed the rainwater running off the roofs by almost an hour. The reason why roof gardens can do this is that the leaf-covering of the variety of plants in a roof garden as well as soil's capacity to hold water. This is good news for environmentalists: the soil can filter out harmful pollutants from a rooftop before it runs off.

How to Get Started with a Roof Garden

Preparing Your Roof

The first step in starting a roof garden is to assess how much weight your building's roof can support. It's advised to find an engineer who is licensed to consult on rooftop gardens; it's a legal requirement in the United States. An engineer can help create preliminary designs, navigate around limitations, and assess the total weight of your garden and the carrying capacity of the roof.

Review with your city's building codes and ordinances; some areas may not allow roof gardens. Sometimes there are legal limitations and restrictions on the height of a rooftop garden, on the spatial usage of a commercial or residential roof, and decorative appearances. If you are planning to create a roof garden on your house, ask permission from your landlord. In some cases, you may have to ask permission from your neighborhood association or district leaders.

Before you grow a garden, monitor the amount of sun and wind exposure your roof receives. Note the patterns of sunlight that reaches your roof over weeks or months. This is an important consideration because the variety of plants you grow require certain amounts of daily sun exposure.

Concerning wind, higher altitudes tend to experience more wind than ground level. It may be a good idea to create a structural scaffold that can support your plants. Some plants can quickly die from strong wind exposure. Additionally, since wind can dry out water more readily, plan to water your plants often.

After all of these considerations, map out a rough sketch of your garden so that you keep your rooftop organized as you construct your garden. Scale the design on graphing paper and then draw in measurements of what you plant to have on your roof.

Purchase Plants

Try to purchase plants are native to the area of your building. This ensures that the ecosystem remains stable: plants of the native climate already have a place in the climate and attract native pollinating species like certain birds and bees. Ask the local farming and gardening community about which plants are native to your area for your options.

Additionally, for longevity-sake, look for drought and heat-tolerant plants; they are better suited for exposure to extreme heat and wind. Look for trees or plants that have larger surface areas on their leaves; they add shade plants less tolerant to hot weather.

Plan to plant small trees and shrubs. Small trees and shrubs exert less weight on your roof and can protect windbreakers and plant support structures. If you do choose to plant trees, trim your their roots every few years to prevent them from growing larger.

If you choose to plant large-leaf plants, try to find species of plants with that is wind-resistant. Alternatively, you can choose smaller-leaved plants or pines. They grow particularly well on a garden roof.

Creating Your Garden

Unless you live in Seattle, use hose or sprinkler system to water your garden will be most space-effective. The easiest and most reliable method to water your plants is to set up an automatic irrigation system. Be sure to plan out where you place your sprinklers; in the long run, it will prevent you from having to hire someone to water each plant. If you can't set up an irrigation system for whatever reason, look for a faucet or water line around your roof, and attach a watering hose to them.

Planting Methods

Plant is well planted on a flat type of pot

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Set up a variety of planting methods: use both soil beds and planting pots. Refer to your graphing paper when placing your planting pots and beds. The right pots and gardening beds should be deep enough to allow your plants' roots room to grow. Once you have figured this out, place your seeds or seedlings in your soil, or transfer plants grown from local gardens in your soil.

Be sure to install trellises to keep your plants alive during harsh weather. You can either build trellises yourself or buy some pre-made at your local home improvement stores. Afterward, place them where they are optimized to break the strength of the incoming wind. Finally, place plants that like to latch to objects, such as cucumber and crawling ivy, or other plants that you think may be fragile.


Plants planted on a big square pot on a roof garden

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Once you know where you will place your pots, beds, and trellises, plan what you will do with your open spaces. Think both vertically and horizontally. Placing objects on a vertical plane will give your roof garden more room. Placing too much on emphasis on the horizontal plane will make your garden less roomy so plant vertically wherever possible. This can give you more ideas on how to use your open space; you may build a walkway or pond, or perhaps add furniture to add to the recreational value of the garden. 


Rooftop garden with village theme

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For aesthetic purposes, create a theme for your garden with focal points as the centerpieces of your garden. An excellent focal point might be a coffee table with seats, a koi pond, or large tree; anything that stands out from the other parts of your garden. However, don't get carried away by adding too many focal points; it can create a distracting effect.

Additionally, try to create a sense of harmony in your garden. Simplicity and balance will go a long way in your garden. Everything you add should serve its purpose. Find benches, chairs, or bird fountains that compliment the theme; consider decorations that are taking up space and now complimenting the theme or focal points.


Rooftop garden with wire nets to hang the plants on

Image via: Flickr

A roof garden is a lovely place for you to escape and it doesn't require much effort into creating one. If you have the desire to grow a garden on your roof, start by looking into city ordinances then measuring the sunlight and wind received on the part of the roof you want to build it. Before you know it, you will have the satisfaction of a garden at the top of your place.


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