Growing Habits of Grasses

On this Page:

• Cool Season Grasses vs. Warm Season Grasses

  • Warm Season Grasses

  • Cool Season Grasses

• Clumping vs. Running Grasses

  • List of Running Grasses

• Hardiness Zones

Cool Season Grasses vs. Warm Season Grasses

Grasses are classified as warm season or cool season, depending on when they are in active growth.

Warm Season Grasses:

These grow when temperatures begin to warm up in the spring. They flower and set seed in summer and fall and become dormant with the onset of winter. Most warm season grasses turn a different colour in the fall, providing colour in the garden before going dormant. Their winter silhouettes, though dormant, can be very attractive and can provide habitat for wildlife. They need to be cut back in late winter or early spring before new growth begins.

Miscanthus sinensis 'Cosmopolitan' (September)

Miscanthus 'Purpurescens' (Fall Colour)

Cool Season Grasses:

These begin growth in late winter or early spring. They flower from winter into early summer and become dormant or slow growing in summer, resuming active growth in the winter. In areas of mild winters, cool season grasses may continue growing all winter. Many are evergreen and require trimming or the raking out of old foliage rather than cutting back.

Calamagrostis acutiflora 'Karl Foerster' (June)

Deschampsia flexuosa 'Aurea' (April)

Classing Grasses based on Clumping vs. Running Grasses

Two other common ways to classify grasses is by their growth habit. Grasses are categorized into either clumping grasses or running grasses. Clumping grasses grow in tufts or clumps. Running grasses spread by aboveground stems or by underground stems called rhizomes. While some running grasses can be invasive, most spread slowly and are easily contained.

The following is a list of running grasses that we grow. A * indicates that they can be invasive:

Hakonechloa macra 'Aureola'

Imperata cylindrica 'Red Baron'

Leymus arenarius 'Findhorn' *

Leymus condensatus 'Canyon Prince' *

Liriope muscari 'Big Blue'

Ophiopogon planiscapus

Ophiopogon planiscapus 'Nigrescens'

Phalaris arundinacea 'Feesey Form'

Sesleria autumnalis

Spartina pectinata 'Aureomarginata' *

Hardiness Zones

Hardiness zones are often used to help determine what plants will be suitable for the winter conditions in your area. Any plant with your zone number or lower will be suitable for your area. This should be used as a general guide, as there are many other factors that may affect the overwintering of grasses and other perennials. These factors include reliability and depth of snow cover, soil moisture levels, and micro-climates of the site.