The Australian summer can be challenging for gardens and green roofs, with extreme conditions, heat waves and lack of water taking a toll on plants. Now more than ever, it is important to adopt a sound management strategy and maintenance plan which accounts for both seasonal change and the holiday period.
Since 1964, the total amount of rain that has fallen in Melbourne in the entire month of December has ranged from 0.8 to 148 millimetres, and for the entire month of January from one to 114 millimetres.
Wind speed and the level of cloud cover (which affects degree of sun exposure) also affect plants, and in December and January, both fluctuate considerably.
In the same months that these large weather fluctuations and heat waves become more prevalent, office buildings and businesses close for the holiday period. This is when gardens, green roofs and green walls feel the pressure. With staff away and Christmas on the horizon, landscape maintenance, like so many other tasks, tends to get put on hold for a number of weeks.
Fortunately, plants are resilient. With the right care, they can bounce back from some surprisingly harsh weather conditions. But their ability to do so varies significantly depending on the speed of response, the plant species and design of the green roof, the length of exposure, and, crucially, how the roof is managed in advance.
Of course, it is critically important to establish a management and maintenance plan plan for your green roof; doing so can help your asset to survive the summer holidays without excessive plant loss or damage.
An effective management plan should always include a strategy and process for responding to extreme weather conditions. For example, a severe storm or heat wave should trigger a routine check of plant health, irrigation and drainage systems, and landscape structures. These responses need to be communicated to both the green roof maintenance and building maintenance team, including any relief staff who replace regular staff members over the holiday period. Instructions on how to respond to extreme weather should also be included in the handover to these relief staff.
When there is no option to continue maintenance during the holiday period, there are a number of steps that can be taken to minimise risk during this time.
- Adjust the maintenance schedule to ensure the green roof is checked as soon as possible prior to and following the holiday period.
- Ensure that irrigation systems are tested and working correctly, and that the timing of irrigation is appropriate for the projected weather conditions. Installing irrigation systems that can be accessed remotely is a good management option which enables you to alter and adjust the watering schedule in response to variations in weather conditions.
- Ensure that green waste systems have been emptied or checked prior to closing the site.
- Reschedule any plant fertilisation to occur in the last maintenance check prior to the holiday period.
- Add mulch where appropriate to protect soil and reduce water loss.
- Check the projected forecast for any extreme or adverse weather conditions expected over the holiday period.
- Where appropriate, relocate pots or moveable gardens to more sheltered sites, or investigate shading elements to protect sensitive plants from sunburn.
While these measures will help to protect your green roof, wherever possible, building owners and managers should arrange for relief maintenance during the holiday period to protect against plant stress and reduce the risk of unnecessary plant attrition. This is particularly important for productive green roofs, as visits may be required to harvest fruit and vegetables, and deal with any pests that affect productive plants.
With good management and preparation, maintaining a healthy green roof over the Christmas period is entirely achievable. A little advance care and preparation combined with a relief maintenance check will ensure that your green roof continues to be an asset and sees the new year in good shape.