A Quick Guide to Green Roof Maintenance

While installing a green roof is a major investment, it pays off in more ways than one. 

A green roof can keep buildings cooler, reduce energy bills, and help the environment. 

But to make sure you're reaping the benefits of your green roof, it has to be healthy and in the best working condition.

Without expert care, irrigation can fail, plants can die, weeds can spread, and drainage systems can clog. Pests and harsh weather can also cause damage. 

That's why regular green roof maintenance is essential. 

Routine inspections and audits, watering, and repairs can help the roof last longer and work properly. 

If you want to enjoy your green roof for years to come, make sure to read this article on how to maintain it.

How to Maintain a Green Roof? 

Green roofs come with a multitude of benefits. 

From reduced energy bills to improved mental health, there are different reasons to install a green roof.

But for your green roof's longevity, health, and performance, maintenance is key. 

Maintaining your green roof doesn't only make it more beautiful. It also contributes to environmental benefits, like improved air quality and reduced urban heat when the garden is in pristine health.

Green roof maintenance is key for:

• Sustaining the roof's health
• Ensuring plant vitality
• Preventing leaks and water buildup
• Prolonging the lifespan of the green roof
• Maintaining the aesthetic appeal 
• Ensuring the structural safety of the roof
• Saving money in the long run

To maximise these benefits, regular upkeep is key. 

To keep your green roof thriving, you need to adopt a regular maintenance plan. Necessary green roof repairs are also essential.

We can divide these maintenance tasks into ongoing and seasonal tasks. 

Ongoing tasks are done regularly, while seasonal tasks prepare the roof for weather changes.

Ongoing Green Roof Maintenance Tasks

Ongoing maintenance tasks are performed regularly throughout the year. 

They can keep your green roof healthy and functional. 

These tasks prevent small issues from becoming major problems. They ensure the green roof continues to provide different types of benefits.

Ongoing green roof maintenance tasks may include:

1. Watering
2. Weeding
3. Fertilisation
4. Drainage
5. Plant care
6. Inspections

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Watering

One of the most important tasks in green roof maintenance is watering.

Regular watering ensures plants stay green and functional. 

Remembering to water your green roof is especially important during the first few weeks after installation. 

Plants need time to establish their roots, which is why regular watering is important in this period.

Irrigation alone won't provide 100% water coverage for plant establishment in this important phase.

Watering should be done daily for the first two weeks. If there is no heavy rainfall after that, a regular schedule is recommended.

How often you should water your green roof depends on:

• The type of green roof you have (extensive vs intensive green roofs)
• The plants
• The local climate

In some cases, extensive green roofs can thrive without constant watering. 

Choosing the correct plants helps these types of green roofs survive with just rainwater and minimal irrigation inputs.

But you'll want to pay special attention during warm and dry periods. 

Intensive green roofs need regular watering as plants have higher water needs.

Always check the moisture level of the soil before watering.

Weeding

Weeding is a crucial part of green roof maintenance. It prevents unwanted plants from taking over. 

Weeding is important because it:

1. Prevents weeds from competing for nutrients and water 
2. Reduces the weight load of your green roof
3. Protects plant health
4. Keeps the green roof looking good
5. Ensures proper drainage 

In other words, weeds can reduce the effectiveness of the green roof.

You should inspect and weed your green roof every two to four weeks during the growing season. This will prevent weeds from flowering and dispersing seeds. 

This routine secures the health and structure of your green roof.

For newly installed green roofs, you should check for weeds weekly. But for established green roofs, do a weed inspection on a monthly basis.

During peak growing seasons, you should check more often since weeds grow faster.

Fertilisation

Fertilisation is a key part of green roof maintenance. It ensures plants receive the nutrients they need to stay healthy and thrive. 

Nutrients in the soil can be depleted over time. This is especially true for extensive green roofs with shallow substrates.

Proper fertilisation helps:

• Maintain plant growth
• Improve resilience
• Reinforce the roof's environmental benefits

Fertilisation should occur at least once a year for extensive green roofs. Ideally, in spring and optionally late summer or early autumn. 

You should choose a slow-release fertiliser to complement the plants used.

Soil tests may reveal that there is no need to fertilise your rooftop garden so frequently. In that case, it's okay to decrease it after three to five years.

Intensive green roofs should be fertilised every two to three months during the growing season.

When it comes to newly installed green roofs, you should fertilise lightly to help plants establish roots.

Make sure to use organic fertilisers where you can, like compost or organic matter. 

Drainage

A well-functioning drainage system is very important for your green roof. 

Without proper drainage, water can pool on the roof, leading to plant damage, leaks, and structural issues. 

Maintaining drainage ensures that rainwater is absorbed and directed away efficiently.

It keeps the roof lightweight, stable, and functional.

A green roof's drainage system consists of several layers that help manage water flow:

1. Growing medium (soil layer) – Absorbs water and provides nutrients for plants.
2. Filter fabric – Prevents soil and debris from clogging the drainage layer.
3. Drainage layer – Channels excess water to drainage outlets (can be made of gravel, plastic, or drainage mats).
4. Waterproof membrane – Protects the building structure from water leaks.
5. Gutters and drains – Collect and remove excess water from the roof.

It's important to regularly check and clear your drainage system. If there's debris from gutters and outlets, make sure to remove them right away.

Plant Care

Proper plant care is key for a green roof to remain healthy, visually appealing, and functional. 

Plants play a key role in insulating buildings. They can also reduce stormwater runoff and improve air quality.

So, with plant care, your green roof will continue to provide these benefits.

Different green roofs need varying levels of maintenance based on their intensive nature. 

For semi-intensive and intensive roofs, more plant care is necessary. This includes:

• Inspecting the vegetation at least every two months
• Removing invasive plants and weeds manually
• Applying fertiliser annually or seasonally
• Trimming and pruning to encourage plant growth
• Replacing dead or weak plants
• Maintaining a minimum 80% plant coverage

Inspections

Aside from green roof maintenance tasks, regular inspections are also recommended. 

Doing so helps identify and fix potential issues before they escalate. For instance, clogged gutters and drainage problems.

Here are some inspections you should do to maintain your green roof:

1. Check the structural integrity of your roof
2. Monitor plant health to identify invasive weeds
3. Assess the functionality of your drainage system
4. Look for water stains or damp areas inside the building 
5. Inspect for any damage or required repairs

Basic inspections should be done every one to two months. Thorough inspection should be done twice a year, in spring and fall. 

It's very important to inspect your green roof after severe weather. Make sure to look for damage after heavy rain, storms, snow, or strong winds.

Regular inspections are important because they can save you a lot of money in the long run.

If you fix any issues early on, you won't have to worry about costly repairs.

Seasonal Green Roof Maintenance Tasks

Aside from ongoing maintenance, it's also important to maintain your green roof seasonally. 

Green roofs require seasonal maintenance to adapt to changing weather conditions.

Seasonal maintenance includes different types of tasks in the:

1. Spring
2. Summer
3. Autumn 
4. Winter

Each season brings unique challenges. For example, heat stress in summer, fallen leaves in fall, or snow accumulation in winter. 

Doing these tasks ensures that your green roof remains healthy, functional, and long-lasting year-round.

Spring

Spring prepares your green roof for the growing season. It's also the time to recover your green roof from winter damage.

Here are some spring tasks to maintain your green roof:

• Remove weeds by hand before they flower and set the seeds
• Apply slow-release granular fertiliser 
• Clear debris from drainage outlets
• Monitor poor growth areas and overseed if necessary
• Check and prepare irrigation systems
• Inspect the drainage layer for any blockages

Spring maintenance revitalises plants and prevents water damage. It also prepares the roof for warmer months.

Summer

Summer brings hot temperatures and rapid plant growth. During summer, watering and pruning become key priorities.

Summer care green roof maintenance includes:

1. Increasing watering frequency during warm months
2. Watering early morning or late evening to prevent evaporation
3. Continuing regular weed removal
4. Monitoring plant health and soil moisture
5. Ensuring proper drainage during heavy storms

Even though watering is necessary, it's also important not to overdo it. Water only when necessary to prevent excess saturation.

Extensive green roofs require additional water during excessive dry periods. Intensive green roofs need regular deep watering in summer.

Autumn 

Autumn maintenance tasks mainly include preparing for winter. 

As temperatures drop, autumn is the time to clean up your green roof and strengthen plants before winter.

This may include:

• Removing fallen leaves and debris from gutters and drains
• Performing final seasonal fertilisation
• Preparing plants for winter dormancy
• Clearing drainage systems
• Preparing for increased rain by testing water flow in drains
• Checking for roof leaks
• Inspecting the structural integrity of the roof

Winter

Winter green roof maintenance tasks include protecting your roof from excess rain and cold weather.

This may include the following:

1. Winterising irrigation systems if necessary
2. Checking for blockages in drainage outlets
3. Minimising foot traffic
4. Checking for leaks indoors

In colder climates, protect dormant plants. In warmer areas, continue periodic weeding to handle persistent growth. 

Additional Considerations 

These are some additional considerations to think about when maintaining your green roof:

• Safety and training
• Documentation and record-keeping
• Avoiding chemicals

When engaging in green roof repairs or maintenance, tasks should be carried out by trained professionals. 

These professionals should be familiar with both horticultural techniques and safety practices for elevated work.

You may also want to meticulously record all maintenance activities. This includes detailing tasks, resources used, and timings. 

This is key for warranty claims and future maintenance planning.

To protect the roofing membrane and warranty, manual control methods (such as hand weeding) are better than chemical ones. 

Avoiding herbicides and pesticides promotes long-term sustainability. It's also much healthier for the environment. 

Make the Perfect Green Roof Maintenance Plan

Taking care of your green roof is important to keep it working well and looking good. 

Regular maintenance helps plants grow, keeps water draining properly, and protects the roof from damage. 

Doing routine tasks like watering, weeding, trimming, fertilising, and checking the drainage will help prevent problems. 

Seasonal maintenance is also important to prepare the roof for different weather conditions. 

If you want to know more about how to maintain a green roof, Evergreen Infrastructure can help. 

We're a team of green roof experts, along with other green spaces in urban areas. 

Not only do we specialise in designing and building green roofs, but we also know how to take care of them.

Reach out to us if you have any questions. 

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