Ornamental Grasses for New Mexico Landscapes

Southwest Yard & Garden by Dr. Marisa Thompson

 

Figure 1. Blue grama (Bouteloua gracilis), the state grass of New Mexico, photographed in November 2017 near Carson National Forest (photo credit M. Thompson).

Question: Do you have recommendations for native grass species for residential landscapes and how to care for them?

-        Otero County Extension Master Gardeners

Answer: Bigger ornamental grasses provide beautiful backdrops, hedgerows, and screens in our landscapes. Smaller species help fill in between broadleaf plants and make great garden borders. Both big and small grasses provide texture, contrast, and grace, all with minimal maintenance and zero fertilizer. In winter, when many of our ornamental plants have shed their leaves, grasses can be delightful, even though they’re dormant and brown.

When selecting native grasses for your garden, pay attention to plant height, space needed, and cold hardiness that matches your growing zone. To get you started, here are a few of my faves, organized by size from very big to small: giant sacaton, alkali sacaton (flowers smell like rancid butter in spring but in the best way possible), weeping lovegrass, big bluestem, little bluestem, sand lovegrass, Indian ricegrass, all the grama grasses (including blue, black, and sideoats), and buffalograss. Find more info about ornamental grass species selection below!

Several species are highly controversial. For example, some folks hate pampas grass (non-native) and others can’t stand needle-and-thread grass. Both are considered invasive in some parts of the country where they are not native. I’m a big fan of both. The pampas grasses growing in my apartment landscape in Albuquerque and in my Las Cruces yard were huge and beautiful. The only thing I didn’t like was those razor-sharp, barbed leaf blades when it was time to prune them back. Stipa neomexicana (needle-and-thread grass) is native in New Mexico, but just because it’s native doesn’t mean it can’t also be invasive-like. I like finding spots where it’s spreading in my yard as the new plantlets pop up. The problem I have with this species is that the seed heads get matted up in the late summer and can droop down in an ugly way. To get around this, I comb through them quickly with my fingers and disperse the seed clumps around the garden.

All too often, gardeners and landscapers prune back the clumps too short and too early. Unlike broadleaf plants that produce new (meristematic) growth on the tips, the origin of new tissue in grasses is at the base of the plant, so if they’re cut down too low to the ground, that meristematic region can be irreversibly damaged. And the timing of pruning is key because that above-ground mass of brown grass provides protection for the base through the winter.

It’s best to clip back the dead grass leaves in early spring so new green growth gets plenty of sunlight. If you have to prune grasses back earlier in the year, for instance, because they’re overflowing onto a garden path, consider cutting back minimally, or dig up the whole plant and move it to a space where it can spread all it wants.

Helpful tip: Use string (or a bungee cord) to belt the dead grass bundle before cutting to keep the mess down and make it easier to move the whole mass to the compost pile. Clippings make great mulch around other plants in the garden too. If you waited long enough to do this work, the seeds will have mostly fallen already, and you don’t have to worry about grass seeds sprouting in places you’ve mulched.

Clumping grasses, like miscanthus and many muhly grasses, tend to form a ring shape as the center dies over the years. This can be alleviated by dethatching that inner part when you prune. You can use your fingers and rake the matted grass out of the center or go at it with a gardening tool to aerate the roots in the middle. Alternatively, many perennial bunching grasses can be divided and propagated easily by digging sections out and replanting elsewhere.

In an ornamental grasses lecture given last February, UNM professor, garden author, and landscape designer Judith Phillips pointed out that native and adapted grasses are wonderful for our xeric landscapes because they are well suited for low precipitation, high summer temperatures, and tons of sun. Our desert soils tend to be low in organic matter and high in mineral salts, including calcium carbonate (aka caliche, not the custard kind), but many grass species thrive in these exact conditions. Their fibrous root structure acts as an excellent soil binder, which helps control erosion and improves soil health. As roots grow and die, they help with soil compaction and add precious organic matter.

MORE RESOURCES:
1) The NMSU Extension Guide "New Mexico Range Plants, Circular 374" includes a nice list of native grasses with descriptions: http://aces.nmsu.edu/pubs/_circulars/CR374_LG.pdf.

2) The Ladybird Johnson Wildflower Center also serves as a great resource when you narrow the search to grasses for New Mexico: https://www.wildflower.org/plants/combo.php?fromsearch=true&distribution=NM&habit=habit_grass&duration=

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the NM Desert Blooms Facebook page (@NMDesertBlooms)

Please copy your County Extension Agent (http://aces.nmsu.edu/county/) and indicate your county of residence when you submit your question!

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms (http://desertblooms.nmsu.edu/) and the NMSU Horticulture Publications page at http://aces.nmsu.edu/pubs/_h/.

Marisa Y. Thompson, Ph.D., is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, office: 505- 865-7340, ext. 113.