This blog is co-written by Cristina Senjug, Next Level’s communication manager along with Dr. Karen Liu, Next Level’s green roof specialist who was present when Cristina’s residential green roof was installed more than a decade ago.

The Maintenance Pay Off

Summer is a celebration of nature! Everything is full of life. Flora and fauna are flourishing in the long days, bright sunshine and warm air. The extensive green roof on my studio in Toronto is in full bloom of dazzling colours, attracting bees and butterflies galore, absolutely buzzing with life.

We even brought our newly hatched members of the family onto the roof for a supervised play session!

My small investment in spring maintenance is now paying off dividends in a big way.

Here are some additional maintenance tips to help keep your green roof healthy and happy over the summer. 

Weeding 

Weeding and watering are the key tasks in summer. Green roofs are exposed to weed seeds via wind or birds. Weeds grow and reproduce quickly and can choke out desirable plants. Many weeds take only four weeks from germination to flower/seed. Because of the short lifespan, multiple generations can happen in a single growing season. Therefore, weed regularly to break the life cycle and control the spread. 

For mature vegetated roofs, Next Level Stormwater Management recommends a minimum of four maintenance visits in the summer, once in each of June, July, August and September. Remove weeds and their roots entirely. If seed pods have already formed, remove the plant carefully taking care not to disperse the seeds and place it in a bag immediately. 

Easy access to water is required.

Watering 

Extensive green roof plants are typically heat and drought resistant. Native plants are adapted to the local climate. Succulents like sedum store water in their leaves, stems and roots. However, they can experience water stress during prolonged heat and drought. Dried plant biomass can also become a fire hazard. 

Next Level Stormwater Management recommends a hose bib on the roof to provide easy access to water. Irrigate the green roof deeply but infrequently in the summer to promote deeper root growth and resilience. The water requirement is project specific and depends on many factors. Check out Green Roof Irrigation for more details. 

Drains need to be kept clear of growth and debris.

Drainage 

Vegetation around the roof drains can imped drainage and cause ponding. This can become particularly serious during heavy rainstorms in the summer when the rapid buildup of water may overload the roof. Therefore, cut back or remove overzealous growth around the drains regularly. 

Summer storms may also wash loose growing medium and fallen leaves to the drains and cause clogging. Inspect the roof after major storms and clean out debris around the drains to keep drainage paths clear. 

Fertilization 

Check for disease and pest, treat and replace damaged plants if needed. An annual application of controlled release fertilizer in spring is sufficient for most extensive green roofs, although urban agriculture green roofs could benefit from additional fertilization over the summer to boost harvest. 

Need more info? Please check out the LiteN’Less™ maintenance guidelines and handy check list. 

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