Tips On Trimming Ornamental Grasses in St. Louis

In recent years interest and use of ornamental grasses has exploded. St. Louis ornamental grasses can fit into almost any garden theme, and they can lend height, movement and long season color to the landscape.

This proliferation of ornamental grasses has brought a very common question we hear here at Environmental, “Do I need to trim my grass back and if so when?”. “How and when should I divide my ornamental grass?” is another common one.

Grasses are generally classified as cool season or warm season (or evergreens, which are usually plants that look like grasses but aren’t, like sedges for example). The rules change just slightly depending on which type of grass you have.

Cool-season grasses put on most of their growth in spring before temperatures exceed 75 degrees and in the fall when temperatures cool down. They typically maintain good color through the summer, but won’t grow much when the heat is here. Warm-season grasses however won’t start growing until mid to late spring, sometimes even early summer. Their major growth and flowering happens when the weather is hot.

They will usually turn shades of brown for the winter, and are often cut down in the fall, though some will leave theirs in place as the dried grass and seed heads in the garden add winter interest. Snow or ice encrusted ornamental grasses can also be quite beautiful.

For both warm season and cold season grasses, the end of February and beginning of March is a good time to cut either of them back. Warm grasses can be cut almost to the ground (you can leave a few inches as well) before new growth begins. Cool season grasses tend to look good even as the weather cools. Leave their foliage in place until now before trimming. Also leave about 1/3 of the plant in place: trimming cool season grasses too harshly can irreparably harm the plant.

Dividing grasses is one way to increase the number of plants without spending more money. Occasional division will also help grasses remain active and growing and can help renew older grasses. Some grasses, over time, will die out in the center and dividing will rejuvenate the clump.

You can divide warm season grasses anytime spring through mid-summer, for cool grasses spring or early fall is the best time. 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 they won’t establish a good root system. 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 will tend to bloom in mid to late summer.

After you have trimmed your ornamental grasses, this is also the time of year when you want to head out and prune back any broken or unwanted branches from dormant trees, so they look their best when springtime gets into full swing in a few weeks.

And now is the time to do one of most enjoyable tasks of the year – going through your outdoor spaces and imagining all of the new possibilities this year with new plantings, all kinds of design changes, water features, landscape lighting; the full list of things we offer that can make your home and property look better than ever before!

So now is the time to contact your St. Louis landscape professional for scheduling your spring maintenance or your landscape installation for this year.  Please give us a call at (636) 225-3848.