Rooftop gardens have been gaining popularity lately, and are slowly turning grey, industrialised city roofs into green paradises. While many people understand that rooftop gardens contribute to air quality by creating oxygen and are useful for growing edible plants, the full scope of benefits is not well known.

Rooftop gardens can help improve your health and wellbeing, as well as cut back on climate control costs within the home. Some cities in France, Switzerland and Canada have laws that stipulate new and renovated flat roofs must be ‘greened’. Read on to understand the ins and outs of adding a garden to your roof, and how you can contribute to the evergrowing environmental trend.

Fixing the Future

Rooftop gardens hold multiple benefits for the surrounding environment. A common problem in cities is that they experience what is known as the ‘urban heat island’ effect, which is caused by the sun warming up manmade products like concrete and asphalt to make an ozone layer of heat that permeates the city year-round. While that doesn’t sound like such a terrible issue in winter, it can be dangerous in the warmer months.

Australians have long been told our temperate climate is one of the best in the world, but with an increase in city density, the urban heat island effect can make living conditions dangerous and expensive by increasing the temperature drastically. The installation of a rooftop garden can significantly lower the amount of heat that radiates on your rooftop, which lowers climate control costs for the inside of the home.

Control The Flow

An issue that affects cities all over the world is the amount of stormwater runoff that accumulates from rooftops, even after light rain. The runoff flows into streets and drains, which can cause flooding and contaminate the bodies of water it’s directed through. Stormwater can carry many different pollutants including oil, fertiliser and everyday litter, which creates a major environmental problem that is expensive to fix. Rooftop gardens can retain 40–90 per cent of stormwater runoff, which in turn helps the environment.

Clear The Air

Air quality is a serious and deadly issue in many countries around the world. The countries worst affected are India and Pakistan, where the dangerous PM2.5 pollutant found in smoke and dust is at 153 micrograms per square metre, with anything above 35.5 micrograms per square metre considered unhealthy.

The PM2.5 pollutant, carbon monoxide and nitrogen oxides all contribute to what’s been labelled the ‘sick building syndrome’. This syndrome is the root of the rise in allergies, headaches and fatigue among city dwellers and can also cause cancer, nervous system disorders and even death.

Air pollution doesn’t just affect our bodies – it can also reduce crop yields while harming fauna and flora. As Australian cities grow denser, the inclusion of rooftop gardens can help relieve some of the increasing air pollution, as plants generate oxygen and trap dust.

Miracle Plants

Plants that remove pollutants (such as benzene, formaldehyde and trichloroethylene) from the air include the peace lily, florist’s chrysanthemum, red-edge dracaena and the barberton daisy. The areca, lady and bamboo palm trees are also great options that improve air quality and encourage a tropical atmosphere.

Spending time surrounded by nature has the ability to boost our physical and mental wellbeing. Even before there were scientific studies to prove it, we felt the emotional benefits instinctively. While scientists can’t quite figure out the reason behind it, studies have concluded that those who spend more time in nature tend to feel better than those who don’t.

Mentally, time spent around plants can help improve short-term memory and alleviate stress, while also reducing mental fatigue and the symptoms of depression. Our creativity, concentration and vision are all enhanced, while inflammation is reduced and our immune systems are boosted. All of this can be accomplished by simply spending some time in a rooftop garden, which aids in longevity and overall happiness.

Take Your Pick

Green roofs are the most popular type of rooftop garden, as they can be customised to accommodate almost any structure. There are three main types of green roofs that require low to high maintenance. The lightest option – which is best suited to weaker roofs – is called the ‘extensive’ green roof, while the heavier ‘semi-intensive’ option has denser soil and requires a sturdier roof. The ‘intensive’ green roof is only suitable for very durable, well-supported rooftops as it contains large amounts of soil and vegetation.

The Extensive One

The extensive green roof contains 7–13cm of soil, which supports mosses, sedums, succulents, herbs and light grasses. After its short initiation period of a few months, this garden will need little upkeep. This option is widely used as it contributes to the environment while being cost-effective, as well as acting as a cover to extend the life of your roof by up to 40 years.

A container garden makes a great addition to an extensive green roof. This inexpensive type of garden is easy to maintain, can accommodate small- to medium-sized plants and is light enough for weaker roofs. It can be crafted out of any kind of container, ranging from recycled Tupperware or pots to wooden vegetable boxes, which will add colour and variety to the roof.

The Semi-Intensive One

The semi-intensive green roof has become Instagram famous for its ability to cultivate sturdier greenery within soil that’s around 13–18cm deep, including little shrubs and select perennials. Unlike the extensive rooftop garden, flowering plants such as lavender and daffodils can be planted without the aid of containers.

The Intensive One

The intensive rooftop garden is the most high-maintenance and dense option, which is like having a full garden or miniature farm on your rooftop. They are generally found on large concrete structures like apartment buildings that can hold the added weight of 18cm to more than 60cm of soil, and accommodate heavy irrigation and large trees. Often, they double as parks and community farming areas. This option tends to be expensive and requires daily irrigation to support the abundance of greenery. That said, it can be the most beautiful option, as it takes up the entire roof with a variety of flowers and trees.

Make It Great

To grow your own rooftop garden you will need a suitable rooftop, which may be difficult if you’re renting. The first step is to confirm a rooftop garden is allowed by your landlord and local council. Having a professional check how sturdy your roof is before you start carting soil up is very important to avoid any mishaps or costly repairs.