Thursday, April 8, 2010

Growing Grasses in Cold Climates

If you live in Zone 4 or colder, you would be wise to consider not just the hardiness of the grass, but also whether it can be expected to bloom in your short growing season.

Warm Season Grasses

Warm season grasses tend to have more spectacular blooms, but they also bloom late in the season. If you have a short growing season they may only be just starting to bloom when a hard frost hits. Miscanthus is finished once that happens. The blooms that have opened will remain, but the leaves turn beige and no more blooms are produced.

Here is a list of warm season grasses:
In a climate where the soil does not warm up until mid May or later, there will not be any signs of life from warm season grasses before then. You will be emailing us and telling us your plant(s) have not survived the winter! But they are just waiting for the soil to warm up before they send any leaves up. They thrive in hot weather.

So the use of warm season grasses means that part of your garden will look very bare well into the spring. If you have a lot of garden space planted in warm season grasses, your garden will not show any greenery before late May or maybe even well into June. In a climate with a short growing season you may feel a little cheated. Pennisetum is especially suspenseful because it is the very last to grow, waiting until well into May or even June in a Zones 4 or 5.

Cool Season Grasses

The cool season grasses are much better suited to cold climate gardens. They are in a hurry to produce offspring, so they are up and growing and blooming as quickly as they can. They like the cool weather. So they bloom early, meaning that frost won't ruin the blossoms. Many have blossoms that hang around until winter.

Here is a list of cool season grasses:
Cool season grasses, for the most part, bloom in cool weather and shut down in the heat of summer. If they are not allowed to dry out too much they continue to look good, but they are usually done blooming. Seslerias heufleriana and caerulea bloom with the daffodils!

The four champion/pretty-well-fool-proof grasses in the cool season category are:
  • Calamagrostis, particularly Karl Foerster, our top-selling grass
  • Deschampsia - very hardy and Goldtau is absolutely lovely
  • Festuca - many to choose from
  • Helictotrichon - its evergreen in most climates, so that's a real bonus!
So in climates colder than Zone 3, we recommend only cool season grasses. In Zone 3 we suggest about 80% cool season and in Zone 4 about 60% cool season grasses.

On our website we state the blooming time for a grass. The earlier blooming warm season grasses are the ones to choose in a cool climate. For instance Panicum blooms early and is hardy, so it is a good choice.

Of course we understand a gardener's love of pushing the boundaries, so these are only suggestions. Even I do it. In my Zone 5 garden with early sunset of 5pm, I have a Pampas grass that I have nursed back from near death (because I transplanted it at the wrong time!). Last year it started to look happy, but didn't bloom. Maybe, just maybe it will this year....?