By Gary Jones
By Gary Jones
When we think of container growing, we typically default to considering
pots, flats and other plastic vessels in which we place growing media
and a selection of plants that provide esthetic beauty.
When we think of container growing, we typically default to considering pots, flats and other plastic vessels in which we place growing media and a selection of plants that provide esthetic beauty. This year’s CanWest Show exhibition provided an opportunity to view new developments in coco-fibre pots and other containers such as fibreglass impregnated with concrete (which looks fabulous!), and coloured, textured steel planters for larger projects on the patio.
But there were also some interesting products that used building roofs and interior walls as their containers. Take for example the “Sempergreen®” vegetative growing blanket being offered by Paridon Horticultural (check out www.paridon.com).
While this is not a new product (it’s been around since 1996), its simplicity offers an easy entry point for those interested in exploring the green roof concept. Sempergreen is a 100 per cent biodegradable blanket containing up to 11 species of sedum growing in a substrate mix that is built into a rollout coco-fibre mat. This mat offers guaranteed 85 per cent coverage upon installation, thereby improving the chances of success, and the rollout format reduces installation time and maintenance costs.
INSTANT FOLIAGE FOR ROOFTOP PROJECTS
Another interesting product is the MGV GroRoof™ (www.mgvgroroof.com). Interlocking modules contain a customized, lightweight growing medium (Metro D-Lite™) composed of organic materials and minerals. Pre-vegetated, like SemperGreen, these provide instant foliage cover to a new roof installation. The interlocking sidewalls prevent soil loss during planting and establishment, and once installed these sidewalls can be removed to provide 100 per cent soil integration from day one. As part of the system, the MGV GroMat™ is made from 100 per cent recycled polypropylene, absorbing and filtering rainwater. Built-in reservoirs store water, and interlocking channels connect each group of reservoirs. For the opposite drier climate, channels in the base allow for drainage of excess water and for air circulation through the same drainage holes.
So, just how big are the “containers?” For this, given the systems we’re talking about, we need to think of the container as being a roof. A Kwantlen student project1 early in 2011 investigated the potential for green roofs in Langley, B.C. The benchmark was a roof size between 2,000 and 3,000 square metres (approximately half to three-quarters of an acre), since this is similar to the dimensions of the widely proclaimed Lufa Farms green roof (vegetable) initiative in Montreal.
The student project used “Geo Cities,” a geographical mapping program, to apply that benchmark to rooftop outlines within five kilometres of Kwantlen Polytechnic University in the City of Langley. A total of 25 rooftops were measured as being above this size. Measurements are approximate, but 15 rooftops appeared larger than 3,000 square metres, for a total of 63,016 square metres and with an average size of 4,201 square metres.
CASE STUDY: ASSESSING GREEN ROOF POTENTIAL
A further 10 rooftops measured between 2,000 and 3,000 square metres, totalling 23,880 square metres (an average of 2,388 square metres). So, there is clearly significant opportunity for application of such green roof “containers” if size is the only criterion. Note, however, that from an overhead perspective, the pitch of these roofs is not considered, merely the overall footprint. So, too, roof suitability for retrofit green roof installation has not been considered.
If going on the roof is not your cup of tea, Northern Innovators in Langley was exhibiting the new “Smartwall,” due for launch in January 2012 (www.smartwall.ca). This is described as “an innovative self-watering vertical garden for interior spaces.” Flowering plants can be “mix-and-matched” into colourful murals (the display at CanWest used stunning displays of pots of begonias and gerbera, for example) or indeed can provide fresh herb gardens for restaurant kitchens or even a company cafeteria.
And, crucially, should plants start to fade or their health deteriorate for any reason, individual pots can simply be removed and replaced in a matter of seconds – it really is that simple. If there are 87,000 square metres of large rooftops in a small city like Langley, think just how much interior vertical wall there is just waiting for its share of container plants.
1 Colligan, Cynthia (April 2011), “Are there rooftops large enough for greenhouse applications in the City of Langley?” HORT 2372 poster presentation.
Gary Jones is Chair of Production Horticulture at Kwantlen University, Langley, British Columbia. He sits on several industry committees and would welcome comments at Gary.Jones@Kwantlen.ca.