How to Maintain Ornamental Grass in Edmonton

How to Maintain Ornamental Grass in Edmonton – And When is the Best Time to Cut Back Ornamental Grasses

The two most common questions many of our clients ask about how to maintain ornamental grass is… “when is the best time to cut back ornamental grasses?” and “how and when should I DIVIDE my Ornamental Grasses?”


Fact is… we have been introducing Ornamental Grasses into our Edmonton Landscaping OutdoorSpace Designs for a number of years, as they provide a “natural” look and really compliment certain types of hardscape features such as Ponds and Waterfalls. With that said, Ornamental Grasses can fit into almost any Edmonton OutdoorSpace Landscape Design theme. They are also quite hardy due to their tolerance to drought like conditions, so they are quite popular if irrigation is a concern.

Ornamental Grasses vary in height depending on the species and they add color to the landscape throughout the different seasons. Along with the proliferation of Ornamental grasses have come a host of questions on how best to care for them.

In order to shed some light on these amazing plants, we have created some general rules to follow when cutting back and dividing Edmonton Ornamental Grasses.

Grasses are generally classified as “Cool Season, Warm Season or Evergreen” and the rules change slightly depending on which type of grass you have.

Cool Season Grasses

Cool Season Grasses put on most of their growth in spring before temperatures begin to get hot (exceeding 24 degrees Celsius) and in the fall when temperatures cool down. They generally maintain good color throughout the summer but won’t grow too much when it’s hot.

Cool Season Ornamental Grasses

Warm Season Grasses

Warm Season Grasses don’t start growing until mid to late spring or even early summer. Their major growth and flowering happens when the weather is hot and they will usually turn “shades of brown” for the winter.

Warm Season Ornamental Grasses Warm Season Ornamental Grasses

Evergreen Grasses

Evergreen Grasses are plants that “look like grasses” but are not actually classified as “grasses”. Examples are “Sedges” and “Carex”.

Evergreen Ornamental Grasses

There are a few (general) rules of thumb that pertain to the maintenance of most grasses.

When is the Best Time to Cut Back Ornamental Grasses?

Rule of Thumb #1 – Cut-back “Warm Season Grasses” in the fall or by early spring

Warm Season Grasses turn shades of brown as the weather turns colder. Once your warm season grasses turn brown you can trim them back at pretty much any time.

Fall is typically the best time to cut them back when you are cleaning up your OutdoorSpace and preparing it for the coming winter. If you prefer, you can leave the dried grasses and seed heads standing for the winter.

Some of our clients prefer to leave their “Carl Foerster Feather Reed Grasses” as they add some additional “dimension” and “colour” to their snow covered and otherwise bare OutdoorSpace during the long Edmonton winter months. The only drawback, given that these grasses typically stand 4-5 feet high, the stems and specifically the ones with heads have a tendency to break and lean over with the accumulation of heavy snow. This doesn’t look so good in the spring when the snow and ice melts, so that’s why some clients elect to cut them back in the fall and save the mess.

When is the Best Time to Cut Back Ornamental Grasses?

If you would prefer to cut them down in the spring, you need to do this after the snow and ice pack has melted and just BEFORE the new growth starts to show its face.

Word of caution: if you leave it too long, the cutting back process will essentially “change the shape of the new growth”, which will result in funny looking grass blades as a result of the tops being straight instead of pointed. At OutdoorSpace we like to refer to this as subjecting your grasses to a “Mohican” haircut. Trust me… your grasses won’t like that!

How to Maintain Ornamental Grass in Edmonton

In order to encourage and stimulate new growth, it is recommended to cut them down to about 6 inches above the ground. We also recommend the “thinning” of the dried stumps that are left. If you take your hand and gently squeeze your fingers around the stumps and pull upwards, clumps of dead stumps will easily pull out.

Word of caution: Be careful not to pull on anything that meets with any type of resistance, as you may pull the root base with you in the process.

Rule of Thumb #2 – Cut-back “Cool Season Grasses” in very early spring

Cool Season Grasses tend to look good even as the weather cools and we head into winter. Leave the foliage in place until spring and then as soon as the snow and ice pack has melted you can cut them back. Once again, do this before the new growth starts to show its face. Leave about 1/3 of the plant in place.

Word of caution: Trimming Cool Season Grasses too aggressively can severely harm the plant!

Cutting-Back Tips & Tricks

First things first, you need to find a GOOD pair of gloves, thick leather gloves are recommended as some Ornamental Grasses can have very sharp edges, plus there may be some unsuspecting “surprises” lurking in the foliage below. If you have ever grabbed a broken thorny Barberry stem by accident, you will know exactly what I mean!

For smaller grasses a pair of hedge pruning shears typically work the best. With that said, make sure the shears are sharp otherwise they will have a tendency to “rip and tear” instead of providing you with a nice clean cut. Trim about 2/3 of the plant for Cool Season Grasses. For many grasses we recommend that you tie the grass in a bundle before trying to trim, this makes it so much easier to make the cut, plus it makes it so much easier to clean up. This is best accomplished with the aid of an assistant. Grab and bunch the stems together. Once you have them bunched together you can tie them together with garden twine or electrical tape. Trust me, it makes the cutting and clean-up process so much easier. If you don’t do this, you will have a MILLION pieces to pick up after you are done. Trust me… it’s NOT much fun!

If you have a large established clump of grass, we recommend cutting them down in smaller clumps. Electric or gas powered hedge trimmers work great if you have one of those machines, but they tend to leave a bit of a mess. Once again, tie the stems together. You can toss the bundles in to your compost pile or bag them and have the city garbage crew pick them up for you.

Dividing Tips & Tricks

Dividing grasses is one way to increase the number of plants without spending additional money. Occasional division will also help grasses remain healthy and can help regenerate older mature grasses. Some grasses, over time, will die out in the center, so dividing will definitely help to rejuvenate the clump and prolong their life.

All Ornamental Grasses should be divided when they are actively growing but not while they are flowering. If the plants are dormant when they are transplanted there is a good chance they won’t establish a good root system and will eventually perish.

Warm Season Grasses generally start growing in late spring or early summer and have their active growth period during the heat of the summer. Warm Season Grasses such as “Little Bluestem and Pink Muhly Grass” tend to bloom in mid to late summer as they flourish in the heat.

Cool Season Grasses are actively growing in spring as they prefer the cooler temperatures. When it starts to get hot these grasses typically go “dormant”, often browning (drying) out. These grasses can be transplanted at either time of the year but early spring is probably the best time to divide them. If you do divide them in the fall, be careful that the freeze/thaw cycles of winter don’t impose an adverse (heaving) effect that essentially will “lift” the plants out of the ground. This will expose their root system and will likely result in the plant dying altogether.

Evergreen Grasses never go dormant. Dividing plants wounds them to some degree. For Evergreen Grasses this wounding will really affect their ability to make it through a cold harsh Edmonton winter.

How to divide Grasses? For smaller grasses it is very similar to dividing a perennial. You dig up the grass clump and then use your hands, a pair of pruning shears, a knife, a sharp shovel or trowel to cut or pull the clump into several (smaller) pieces. Make sure that each piece has some roots attached. Be sure to replant them before the roots dry out. If you don’t plan on planting them right away, make sure you keep the root base moist and covered until you are ready to transplant them.

Word of caution: Grass leaves can be VERY SHARP, so please wear gloves to protect your hands! I can tell you from personal experience, grass cuts are similar to paper cuts… they may be small, but they can REALLY HURT!

For larger grasses you can use the same basic principles for dividing, but due to the sheer size and toughness they can be a lot harder to handle. It can take a strong back (or two) to get some of these very large grasses out of the ground due to their mature and established root base. Dig or pry the clump out of the ground using a garden spade and then divide it into pieces. Once again, making sure each piece has some roots attached. Extreme caution must be exercised when removing the root base, as you want to extract the plant from the ground with plenty of soil attached to the roots. I prefer to utilize a very sharp shovel, but you can use any number of tools such as a reciprocating saw to divide the plant into smaller pieces. Remember… the bigger the plant, the tougher they are to handle!

If you’re concerned about the soil falling off and if your main clump is still looking quite healthy, you can replicate the plant by removing small chunks of the grass from around the outer edge. This may be easier than removing the entire plant and far less stressful on the plant.

Once you have the pieces removed from the main clump, trim off any dead material, replant the pieces as quickly as possible making sure to fertilize and water-in the plants thoroughly.

Word of caution: newly divided grasses will need frequent watering until such time they become established. Once they are well rooted you should be able to decrease or quit watering altogether.

We trust you found this article about how to maintain ornamental grass both informative and educational?

Should you have any questions on how to maintain ornamental grass, or if you need some help with your Ornamental Grasses, we would love to hear from you!

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