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Roof Gardening: Exploring the Pros and Cons of a Roof Garden

People in urban environments lack the property to grow their own food. Therefore, they rely on the availability of reliable suppliers, and it’s incredibly expensive/difficult for them to access healthy/organic food. At least, this is what some people choose to believe.

In reality, where there’s a will, there’s always a way. People in urban environments use their rooftops and terraces to create small private gardens. This can provide them with urban greenery, improve air quality, reduce noise, and boost recreational and relaxation capacities.

Even more importantly, a roof garden can be used to grow vegetables or herbs, which can be used in your diet. You can also set up a rooftop oasis (a mini-park) for rest and relaxation.

With that in mind and without further ado, here are a few considerations for those thinking about a rooftop garden.


Pros and Cons of Roof Gardening

Roof garden on top of an apartment building

Advantages of a Rooftop Garden

The idea of a rooftop garden sounds complex and compelling. In other words, before you attempt to undertake this ambitious project, you need a good enough reason to make an effort.

With that in mind, here are some of the biggest advantages of considering this project.

Urban Greenery

Urban greenery is scarce and invaluable. This is why, on a sunny day, all the parks are crowded. There are numerous environmental benefits to each shrub, tree, and patch of grass in an urban environment. These plants absorb harmful gasses and release oxygen, thus purifying the air.

Greenery helps people reconnect with nature, improving their physical and mental health. You see, humans are meant to roam the forests and planes, and while living in major metropolitan areas has numerous quality-of-life advantages, it’s not the same. This way, the negative aspects of urban living can be slightly mitigated.

Not to mention the many social and community benefits of having a garden where an entire building or neighborhood can gather to chat, play chess, or watch children play.

All in all, it’s a project that can bring a community closer together. However, it also takes an entire community to run.

Food Production

There are two types of rooftop gardens: park–like (mini trees, shrubs, hedges, vines, etc.) and vegetable/herb gardens. The latter is far more pragmatic and can be used for health- and budget-related purposes.

One of the biggest challenges in agriculture is finding more space. Well, rooftop gardening is the epitome of utilizing underused space. Sure, it requires some investment, but it allows you to utilize the unused space in the best way imaginable.

Another thing it does is improve food security. Of course, on the one hand, it won’t be able to produce that much, but it’s something. If you can harvest just one herb/vegetable off the roof, that’s one fewer thing whose shortage you’ll have to fear.

Regardless of its function, all the above-discussed benefits still apply. A vegetable garden can be highly aesthetic and a much better place to socialize with neighbors than any indoor location. The beauty of the backdrop alone would be unparalleled.

It’s also worth mentioning that with concepts like hydroponic systems, this rooftop food production yield may become far bigger than you would expect.

Benefits of Roof Gardening

Increased Property Value

Every additional feature boosts the property value of your home, but when it comes to rooftop gardens, the difference is simply astronomical. There are many reasons behind this.

First, the aesthetics of the building go drastically up. Even more importantly, this is a relatively rare feature, which means that while your apartment has access to its own roof garden, other apartments of the same size and setup won’t. When you control the supply, you control the market, and few such options are available.

Community benefits always go into the value of the apartment unit. It’s like selling a home that has a pool on the rooftop. It doesn’t take an economic mastermind to determine why this apartment would sell well. Add the social aspect (we’ve also addressed it), and you’ll get a huge difference.

Bigger Picture of Having a Roof Garden

Many studies suggest that when a single house installs solar panels on its rooftops, other homeowners in the neighborhood follow suit. There’s no reason why this wouldn’t be the case with rooftop gardens.

A sole roof garden, while great enough to help with the nutrition of one family or even supplement the nutrition of the inhabitants of that apartment building, isn’t enough to introduce much change. However, if the entire block followed suit, it could positively impact the local economy.

The same thing goes for the air quality. A single building with a rooftop park is better than no rooftop garden; however, what if the entire neighborhood decided to do so? This could make a massive difference. Either way, it represents starting a positive trend.

Now, one of the biggest concerns people are expressing is the issue of cost, but this could also change over time. As more neighborhoods embrace this trend, the demand will grow, which means the industry necessary to catch up with this trend will also increase.

The materials, equipment, and skilled labor will become more available. With more companies performing these services, the competition will grow, positively impacting the market’s cost and quality.

Disadvantages of a Rooftop Garden

Now, not all are ideal with a garden rooftop either. There are some problems, obstacles, and difficulties that you need to take into consideration before engaging in this ambitious endeavor.

Added Weight to the Roof

The first problem you’ll encounter is the added weight the roof structure will carry. This is something that you will have to consult a roofing constructor about. You see, the roof of an apartment building is heavy as it is. Now, imagine adding the weight of the vegetation and the soil needed to support it.

Not just that, but also the soil needed to provide nutrients and the construction to create these garden beds. Then, there’s the issue of rainwater which will soak the soil, further adding to the weight.

Ultimately, you may also keep some gardening equipment up there, and a rooftop garden will receive more visitors than a regular roof would.

Have you ever heard a story of a library that started sinking because the architect did not consider the added weight of books? While this is more of an anecdote and an urban legend, it’s worth considering.

Rooftop Garden Maintenance

Friends working on their rooftop garden

Perhaps the biggest problem with a rooftop garden is the maintenance you’ll have to invest to make it functional. The thing is that a rooftop environment is not suited for farming or gardening.

While you can make this work, it takes time, effort, and resources. Finding another outlet for your ideas might be best if you’re not ready to commit to them or do this without community/family support.

Another thing you should understand is that accessibility may cause a serious problem. In other words, you need to get all that equipment out there, and you won’t be able to do it all by stairs/elevator.

If something gets broken or needs to be replaced/discarded, you have to repeat the process. This, too, makes your maintenance significantly more difficult.

Pest control is also a huge issue. Where there’s plant life, there are pests. This garden may attract them, and they may infest the rest of the building. You need to be extra vigilant in your maintenance effort to avoid allowing this.

Liability and Insurance

Another thing to understand is that the presence of a rooftop garden increases your insurance premium. This is an additional liability since so many things can go wrong.

The pest infestation that we’ve mentioned is just one of these things. There’s also more plant debris. Since people will spend more time on the rooftop, the likelihood of an accident will also grow.

This is why the property manager must talk to their insurer before any work on the rooftop gets done. This way, if there’s a need for an additional policy or a reassessment, it can be done simply and elegantly.

How to Build a Roof Garden

Making a good roof garden is not a simple project at all. You must figure out what equipment you need, how to get the most out of limited space, and sort out some technical issues.

For instance, what’s the best soil type for a roof garden, and how much soil (depth) do you need? Let’s see if we can answer some of these questions.

How to Build a Roof Garden

How Deep Should a Rooftop Garden be?

There’s no universal answer to this question. It all comes down to your intentions. For instance, if you plan intensive roof gardening, you’ll need a slightly deeper soil profile. We’re talking about 12 to 36 inches.

This is in a scenario where you plan to plant shrubs, small trees, and perennials. If you want one of these plants, consider a more robust root development, hence… you need deeper soil.

On the other hand, extensive rooftop gardening (for sedum, grasses, and succulents) won’t require more than 2 to 12 inches. These plants also require less irrigation and maintenance.

One of the most innovative rooftop gardening methods is the so-called sub-irrigated planters. These require 8 to 12 inches of depth (depending on the plant). The best thing about this method is that it offers more efficient water and soil usage.

Once again, the amount of soil you use will affect the weight of the farm, so make sure to consult a contractor before making any changes.

What’s the Best Soil for Rooftop Planters?

When choosing the perfect rooftop blend, there are a few characteristics that you’re looking for. First of all, the density of the soil changes with the variety. Therefore, you’re looking for lightweight and well-draining soil.

Also, since it’s not in the ground and isn’t as easy to resupply with nutrients, you want the soil you’re using to have a high starting amount of nutrients.

Just remember that this probably won’t be enough on its own. Instead, you’ll have to find the right organic fertilizer and learn how to make compost.

The next important thing is the pH balance. The soil must be within the appropriate range, but if you plan to go for just one type of plant (for instance, if you want to grow tomatoes), you might want to check the best soil acidity in this scenario.

Lastly, you want to use sterilized soil to avoid pests and diseases. This will eliminate the pathogens and weeds within the soil and make your job a lot easier.

Wrapping Up Our Guide to Roof Gardening

If you have available roof space, an interest in rooftop gardening, a solid roof structure, and the means to set up this operation, there’s no reason to avoid or postpone it.

The thing is that some of these obstacles may be too big for a lot of apartment or apartment building owners to overcome. Other than that, it’s hard to find a better way to repurpose your roof space than to start a roof garden.

About the Author Lane Perry

Lane shares her knowledge and creative ideas with our audience at Sumo Gardener as an exterior decorator. She has previously worked as an exterior decorator on home renovation projects across the west coast USA, adapting to different environments for both large and small homes. When it comes to transforming your outdoor entertainment space or coming up with creative ways to enjoy your garden, Lane is our expert.

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