Grasses in the Landscape

General Guidelines for Grasses

Compared to many ornamental plants, grasses need few inputs to perform well. While each grass is different, there are some general guidelines when using and managing them. Check individual plant profiles for specifics.

Growing conditions:

1. Most true grasses prefer full sun. Some will tolerate partial shade, but growth and flowering will be reduced. For shady areas, sedges offer more options.
2. Grasses tend to be tolerant of variable soil and growing conditions. They're seldom picky about pH levels and will do well with a range of soil textures.
3. Most do best in well-drained soil. Some will tolerate wet feet, but for others, poor drainage can decrease survivability, especially in winter.

Planting

1. Soil preparation depends on the grass. Many prairie species prefer poorer soils with low fertility and moisture levels. Amending the soil, adding fertilizers, and irrigating beyond the establishment phase can cause problems. Conversely, other species such as Pennisetum thrive with additions.
2. Grasses are sensitive to soil level. When planting, do not bury the crown. Keep the soil at the same level as it was in the liner or container.
3. Supplemental irrigation helps with establishment, but many grasses won't need irrigation once established.
4. Avoid late-season planting with selected warm-season grasses, such as Muhlenbergia capillaris and Pennisetum alopecuroides.

Managing:

1. For many grasses, there's no need to fertilize. Some varieties will grow larger and fuller when fertilized, but others may put on lax growth that will flop. 
2. Grasses tolerate most pests and diseases well. They are more likely to have problems in nursery or greenhouse settings—where monoculture conditions prevail—than in the landscape. Good horticultural practices (e.g., providing good air circulation, removing diseased debris, and diversifying plantings) will reduce the risk of pests. 
3. For grasses, cut them back once yearly; late winter is ideal.
4. With sedges, especially Asian varieties, cut back only if aesthetically necessary. Carex are slower to recover than grasses when cut back.

Covering Ground with Grasses and Sedges

We think about covering ground literally—planting over bare soil—and in the broader sense of making our landscapes more ecologically sound. A few bare patches in the garden help support wildlife, but too much invites weeds and erosion. Mulching requires regular applications and is resource intense. Our landscapes can be better when we choose a living mulch and cover the ground with plants.

Why? A living mulch will help:

• Capture rainwater before it reaches the ground, slowing runoff and reducing pollutants and sediment that flow into waterways
• Increase water infiltration, recharging groundwater and making it available for plants
• Retain soil and reduce erosion
• Support wildlife, including pollinators
• Reduce weed competition

Grasses and sedges are made for the job. Branching, fibrous root systems hold soil in place while also increasing water infiltration. Dense crowns and abundant foliage slow and filter runoff. Planting densely reduces weed competition, which lowers labor costs and reduces herbicide use. Native grasses and sedges also help support wildlife with food, cover, and nesting material. Landscapes can function better and be more beautiful when we cover the ground. It's a low-resource practice that will supercharge your landscape.

Different Ways to Look at Covering Ground

We find it helpful to think of covering the ground using two general techniques: with large sweeps of one or two kinds of plants or as part of a matrix in a layered, designed plant community.

Large sweeps include what most of us think of as ground covers. They’re plantings of one, maybe two, species that are allowed to grow naturally. They might be cut back once a year in late winter to freshen them and allow for new growth. Lawn alternatives are also large sweeps, but they’re typically mowed periodically (2-3 times a year) to keep them uniform.

A matrix is the base layer of a more complex planting. Grasses and sedges may be mixed in with other herbaceous species to form a matrix at ground level. Larger, taller perennials and woody plants are interplanted in the matrix to give the design coherence and structure. It’s a technique that uses multiple layers to build a designed plant community. There’s a helpful discussion of “the matrix” in this blog post at The New Perennialist.

Choosing the Plants

We’ve curated a list of our plants that fit these techniques and included them in a helpful chart. Our Covering Ground chart includes grasses and grasslike plants traditionally thought of as “ground covers,” along with some not-so-obvious selections. We won’t be picky about definitions. One person’s ground cover is another’s lawn alternative or matrix plant.

As you narrow choices using the chart, we suggest consulting the individual plant profiles in our plant database to finalize your selections. Lastly, note that we cover “lawn alternatives” specifically in our Plants for Green Infrastructure Chart. Check there if you’re interested in selections that can be mowed periodically.

Liners in the Landscape Make Sense

Landscapers and designers often turn to Hoffman Nursery when projects specify plants that are hard to find in larger sizes. Our liners, while smaller than gallons or quart sizes, are well-rooted, and they’re ready to take off when planted in the ground.

There’s a good reason liners do well when planted in the landscape. The soil volume in a small container is limited, yet plants continue to photosynthesize. That excess energy is stored for future use in the root system. When liner plants are freed from their container, this stockpiled vigor bursts into action. Liners typically catch up to larger, finished plants in one or two growing seasons.

More good reasons to use liners:

• They’re cost-effective, especially for mass plantings where you need coverage and easy installation.
• Healthy, high-quality liners establish quickly. Worry less about replacement costs.
• If planted early in the fall, the plants will perform well the following spring.

Hoffman Nursery can custom grow grass and sedge liners for landscape installations. If you need a plant or size that is not in our catalog or on website, let us know. We’ll be happy to give you a quote.

Fall Planting and Winter Survival

Perennial grasses in the landscape generally overwinter with no special treatment. That assumes they’re hardy in your zone and have already established root systems. However, planting warm season grasses too late in the fall can be dicey and may lead to plant loss.

Newly planted grasses can be vulnerable if they are exposed to prolonged periods of severe cold and wet conditions before they’re ready to handle winter. Here in central North Carolina, we recommend planting warm-season grasses before the end of October. Your cut-off time may be earlier or later depending on your climate.

Muhlenbergia capillaris, Pennisetum alopecuroides ‘Hameln’, and Sporobolus heterolepis are three popular grasses that can suffer if planted too late in the season. On the other hand, we’ve planted Panicum species and cultivars (Switchgrasses) in December with no ill effects.

As with all of our growing recommendations, this advice needs to be adjusted to your specific climate conditions.

Cool-season Grasses

Cool season grasses shine when their warm season pals are just getting started or are winding down. When soil and air temperatures are mild (soil 50°-65°, air 60°-75°) and the soil is relatively moist, the cool season grasses are most efficient at their photosynthetic process. They respond with a burst of growth, followed by a flowering period. 

When temperatures rise and rainfall decreases, these grasses have a tougher time getting the sunshine-converting job done. They must open their stomata during the daytime to take in CO₂, and they lose moisture more rapidly than under cooler, moister conditions. All this causes physiological stress, which leads to slower growth and full or partial summer dormancy. 

For those of us with four distinct seasons, cool season grasses usually have two periods of growth—spring and fall. Some species will continue to grow at a lower rate throughout winter. New growth typically begins in late winter or very early spring. A full head of foliage shows up by early spring, and blooms appear sometime in late spring or early summer. 

Once summer hits, with higher temps and drier conditions, the grasses go fully or partially dormant. When cooler temperatures and more moisture arrive in fall, the cool season stars are at it again with renewed vigor and bright, new lush growth. In areas of the country with mild winters, many of the cool season grasses are evergreen or semi-evergreen

For more information, see this comparison between cool and warm season plants and see a list of cool season plants we grow.