There are two types of green roofs when it comes right down to it – intensive and extensive roofs. Extensive green roofing is made up of one shallow layer of planting material, making the choice of plants a little trickier. Intensive roofing is made up of either a deeper planting base or several depths, so choosing plants for it becomes more about the fun than the depth. There are six major considerations to keep in mind when you’re choosing plants for an extensive green roofing project.
Obviously if your roof is pitched so that it is clearly visible to everyone who passes by and has to live across the street from it, you’re going to want to choose your plants wisely for your extensive roof. Many plants have periods in which they are dormant, brown instead of green. You can get around this by either choosing only evergreen plants, or by alternating them so that there are always some plants in their active growing stage so that the roof doesn’t look splotchy.
There are many functions that a green roof can fulfill, and these are also important to consider in your plant choice. If you hate bugs, you’ll want plants that don’t attract them. If you plan on spending any amount of time on your extensive roof, it may be a good idea to choose ones that are visually appealing and smell nice for your pleasure. Managing water during a storm, fitting in with your other green efforts in your landscaping, and even insulation – all of these can be functions as well, so it is important to think carefully before choosing.
Local Environmental Conditions
As much as you’d like to choose plants that only look and smell beautiful for aesthetic purposes, it is important to take your environment into consideration before doing so. Discovering your climate zone can be of help here, as well as considering the roof itself. If it points where the plants aren’t likely to get much sun, take that into consideration. If your plants are going to need to be resistant to drought because of long rainless periods, keep that in mind. Try asking a local horticulturalist or landscape architect for help with this step.
Growing Medium and Soil Blend
The material in which you will be placing your plants is also especially important to the types of plants you choose. With extensive green roofs the soil is often quite shallow, which will limit the variety of plants you will choose successfully. Try getting your growing media into a well-drained, light material that can hold onto the nutrients passing through it without being easily eroded away. Shallow soil means there really isn’t room for those pesky long-rooted weeds, while also drying out quickly, which needs to be considered as well.
Ease of Installation
There are several options available to you as you plant and grow your extensive green roofing. Pre-planted trays or mats of some kind are available for purchase directly from a manufacturer, but these are often so pre-made that you cannot really customize your roof as your own idea. You can grow or buy the plants you want to use as plugs and start them when they reach a level of maturity that is conducive to survival. Another option is to start the plants right on your extensive roof bed from seeds, which can be tricky but very rewarding. Try researching based on your desired plants, as some do not come in plug or tray form, etc.
Northcote Real Estate Agents