Rediscovering Karl Foerster: Why This Overplanted Ornamental Deserves a Second Look

Walking through Minnesota this first week of September, it's impossible to miss the golden spectacle of Karl Foerster feather reed grass in full bloom. Those distinctive wheat-colored plumes are catching the late summer light everywhere you look, from strip mall landscapes to suburban gardens. And I'll be honest – until recently, that ubiquity had soured me on this otherwise spectacular grass.

Karl Foerster (Calamagrostis x acutiflora 'Karl Foerster') has become the landscape equivalent of that overplayed song on the radio. You know the one – initially catchy, undeniably well-crafted, but beaten into submission by constant repetition. For the past two decades, this reliable performer has been the go-to choice for commercial landscapers, and you'd be hard-pressed to find a strip mall, office building, or chain restaurant without a regiment of these grasses standing at attention.

A Tale of Two Plantings

My perspective on Karl Foerster got complicated during a recent lunch with my son. Walking into the restaurant I witnessed both the best and worst of what this grass has to offer, and it reminded me why plant placement matters as much as plant selection.

The "worst" was painfully familiar: a lineup of Karl Foerster plants marching in formation along the street median, each exactly spaced, creating what I can only describe as a living fence of monotony (see the second photo). This military formation approach has become the default installation method for commercial landscapes, and while it certainly provides structure and uniformity, it reduces this beautiful grass to mere landscaping filler – functional but utterly uninspired.

But just steps away, I spotted something that stopped me in my tracks – a gorgeous grouping of Karl Foerster plants arranged in a natural, organic cluster. What made this planting truly special was the height variation: the rear plant stood a good six inches taller than its companions, creating natural depth and visual interest that transformed a simple grass grouping into landscape art. The closer spacing of about 16 inches allowed the plants to flow together as one unified mass while still maintaining their individual character.

Creating Height Drama with Karl Foerster

That height difference got me thinking about intentional ways to create elevation variation with the same grass species. While that restaurant planting might have been a happy accident, I have an idea for achieving deliberate height differences that I'm planning to test this fall.

Mini-Terrace Approach: My theory is that creating a small, elevated planting area using larger stones, pavers, or boulders could provide permanent height variation while maintaining proper planting depth for all specimens. Picture a raised planting zone about 16 inches square and 6-8 inches high for the background plants, built with softball-size or larger rocks that can actually hold the soil in place. This approach borrows from rock garden design principles, where elevation changes are commonly used to create visual interest and improve drainage.

The beauty of this method is that each plant gets planted at its proper crown depth for optimal health, but the elevated growing zone creates permanent height differences that won't equalize over time. Plus, the improved drainage on the elevated area would benefit Karl Foerster, which appreciates good drainage despite its moisture tolerance.

I'm planning to try this technique this fall and will report back next year on how it works in practice. It's still an ideal time to plant cool-season grasses like Karl Foerster in Minnesota – they have plenty of time to establish before winter. The window for warm-season grasses has likely closed, as they need more warm soil time to develop strong root systems before dormancy.

Growing Karl Foerster Successfully in Zone 4

Despite my initial reluctance to embrace this overused grass, I have to admit that Karl Foerster earned its popularity through sheer reliability. This cool-season ornamental grass is perfectly suited to Minnesota's challenging climate, thriving in our zone 4 conditions where many other grasses struggle.

Karl Foerster is remarkably adaptable when it comes to soil conditions, performing well in everything from clay to sandy loam, as long as drainage is adequate. It prefers full sun but tolerates partial shade, though flowering may be reduced in shadier locations. One of its greatest assets for Minnesota gardeners is its moderate moisture needs – it's drought tolerant once established but doesn't mind our occasionally wet springs and summers.

The grass follows a cool-season growth pattern, which means it begins active growth early in spring when soil temperatures are still relatively cool, unlike warm-season grasses that wait for hot weather. This characteristic makes it one of the first ornamental grasses to green up each year and one of the last to go dormant in fall. The timing works perfectly with our Minnesota growing season, providing structure and interest from April through November.

Maintenance and Care

Proper maintenance is refreshingly simple with Karl Foerster. The key timing issue is spring cleanup: cut the entire plant back to 4-6 inches from ground level in late March to early April, before new growth begins. This cool-season grass starts growing earlier than you might expect, so don't wait too long or you'll be cutting through fresh green shoots.

The grass is essentially sterile, producing no viable seed, which means no unwanted seedlings spreading throughout your landscape – a definite advantage over some ornamental grasses that can become aggressive self-seeders. This sterility also means the attractive seed heads persist well into winter without dropping and creating a mess.

For long-term success, plan on dividing your Karl Foerster clumps every 3-5 years to maintain vigor and prevent the center from dying out. Like most ornamental grasses, Karl Foerster can live approximately 10 years without division, but the clumps will gradually develop hollow centers and lose their full, robust appearance. Regular division not only rejuvenates the original plants but also provides you with new specimens to expand your ornamental grass collection or share with fellow gardeners. The best time for division is early spring, just as new growth begins to emerge.

A Change of Heart

Standing there outside that restaurant, watching those naturally arranged Karl plants sway in the September breeze, I had to admit my resistance was softening. The fault isn't with the plant – it's with lazy installation.

When planted with some thought, Karl shows why it became popular in the first place. Those golden September plumes are genuinely spectacular, and the grass delivers true four-season interest: fresh green growth in spring, full foliage through summer, glorious autumn plumes, and solid winter structure.

Companion Planting for Zone 4

Rather than abandoning Karl entirely, I'm advocating for creative partnerships. This grass pairs beautifully with other zone 4 hardy ornamental grasses to create dynamic displays. Try combining it with the burgundy foliage of prairie dropseed for color contrast or pair it with the fine texture of little bluestem.

For a prairie-inspired look, group Karl with 'Northwind' switchgrass and 'Dallas Blues' switchgrass. These panicums grow 5-6 feet tall and offer striking seed head contrast – their open, airy plumes against Karl's tight, upright columns. The different heights, textures, and bloom times create a naturalistic display that changes throughout the growing season. Add native wildflowers like purple coneflower and black-eyed Susan for a low-maintenance landscape that provides wildlife habitat while looking spectacular from spring through fall.

Breaking the Military Formation

My recommendation: resist the temptation to plant Karl Foerster in strict rows unless you genuinely want that formal, hedge-like effect along a fence line or property border. For most applications, consider groupings of three or five plants with slight spacing variations and intentional height differences.

The result is a landscape that feels organic and intentional rather than institutional, with all the reliable performance and seasonal beauty that made Karl Foerster famous.

Your Ornamental Grass Paradise Awaits

I'm warming up to "Karl" again, but with conditions. (That's what we call it at the garden center - “Karl” - a friendly nod to its ubiquity.) Plant it with some thought, give it companions, and create groupings that make sense. When paired with complementary zone 4 grasses and planted with creativity, Karl becomes part of a dynamic, ever-changing landscape.

Have you spotted ornamental grass plantings around Minnesota that caught your eye? Bring your photos to Green Valley Garden Center in Ramsey, and we’ll help you identify the grass varieties and design a plan to create your own ornamental grass paradise. All of the outdoor sales consultants here enjoy helping gardeners move beyond the ordinary.

Fair warning: we're currently sold out of Karl – have been for about a month now. It does sell out despite (or maybe because of) its reputation. And I tell everyone I see buying it the same thing: please don't plant it in a military row. Your landscape doesn't have to look like everyone else's. Together we can bring your vision to reality.

Good growing!

Dave