Choosing the right plants for your green roof is essential. There are plants that need more sunlight and some that need less. Some are more resistant to extreme weather conditions, while some are more fragile and need to be grown under specific conditions. Some plants need lots of watering, while some can get by with weekly or monthly watering, and for some, even just the water they get from rain is enough.
Below, I’ll go through some of the main considerations for you to keep in mind when it comes to selecting the best plants for a green roof in a cold climate.
General ideas to consider
When you’re deciding on your ideal plants, there are three general ideas to consider that’ll make the maintenance of your garden much easier:
Try to plant native species – Natives are those plants that are indigenous to your area and are already accustomed to its specific conditions (the climate, the types of soil, and the amount of sunlight and rain), which makes them more resistant to damage.
Consider drought-resistant plants – They’ll need less water to survive, and it’ll be easier to take care of them as opposed to the more sensitive ones that require more water and care.
Investigate pest-resistant plants – These are a great idea since they’ll require the application of little to no chemical pesticides, as they’ve already developed defense mechanisms against certain pests. A couple of examples include species such as rosemary and sunflowers.
In regard to plants that are specifically well-suited for cold climates, here’s a helpful list of examples—including two succulents, two grasses and a groundcover plant—to get you started.
Succulents are quite low-maintenance, and we can even call them self-dependent to some extent. They’re an ideal choice for your green roof for three reasons:
- They’ll cover a large area of it
- They don’t need a lot of soil to grow
- Their water needs are minimal
Apart from that, there’s also a wide variety of colourful species available that can liven up your roof.
This is a clear-green type of succulent, also known by the name of gold moss stonecrop. It’s good for colder climates because it’s an evergreen and can last for a long time. During summer, it has a special yellow-coloured inflorescence.
Sempervivum means “live forever” in Latin, and that’s also one of the names this plant goes by, along with houseleeks and hen and chicks. It’s a perennial succulent plant that can live for a long time with little maintenance.
Sempervivum plants are ideal for cold climates since they don’t need a lot of sun exposure. They come in a range of colours and can spread easily.
Most types of grass need a significant amount of watering and care, and aren’t very suitable for green roofs and cold climates. However, there are a couple of types that are, and they can make a great addition to your roof garden.
Carex flacca or Carex glauca
This grass species is also called blue sedge and functions as an ornamental plant. It’s damage-resistant and is therefore a good choice for various types of soil and climates, including cold climates. With its blue, round-shaped leaves, it’ll be a great addition to your roof.
Carex elata “Aurea”
This grass is also called Bowles’ golden sedge. It’s yellow and doesn’t need any particular kind of maintenance. It can grow in moist and wet soil, so it’s a good choice for rainy and humid areas as well as cold ones.
A significant characteristic of groundcovers is that they grow horizontally and spread very quickly and easily, preventing the spreading of weeds. This makes them ideal for green roofs.
Ophiopogon japonicus or mondo grass is grass-shaped, but it’s actually a flowering plant. It grows vertically up to 10 centimetres high. It’s an evergreen, which makes it ideal for cold climates, and it’ll give your roof a nice touch of colour. It can grow in the shade or in partially sunny places, and needs moist or wet soil.
Green roofs can flourish almost anywhere
Green roofs or roof gardens are a great sustainable addition to any home, regardless of the climate, especially if you’re unable to have a traditional garden on the ground in your backyard.
If you make an effort to choose your plants carefully and ensure that they’re suitable for colder climates, you too can have a successful and flourishing green roof just as people living in warmer climates do.
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image: Wikimedia Commons