Hybrid Prairie Lawns in Colorado

Turfgrass to the left, natural field to the right, in front of residential complex in Broomfield, CO. The field is actually closer to the complex, which is to the right.

One of the things that has most impressed me during my stay here in Colorado has been the way they have managed to integrate natural components into the suburban and even urban landscape.

The so-called Open Spaces is one aspect of this. but I also found smaller examples that were even more immediate and accessible to people.

Turfgrass to the left, natural field in front of residential complex to the right

In many places I've visited, including Broomfield and Boulder, landscapers have integrated traditional lawn and ornamentals with natural fields of grass and forbs around residential and commercial buildings. In the picture above for example, traditional turf grass that remain cropped close to the ground stands next to an open field. 

Turfgrass lawn backstopped by natural grass field, in front of residential building

These hybrid prairie lawns (HPL) are quite attractive, and the natural fields pull the eye away from the rather dull and relatively boring turfgrass. Unlike turfgrass lawn, the natural fields changes in appearance over the course of the season, with more green tints in the earlier parts of the year, before the golden light browns of summer and fall as the grasses senesce. Another big positive is the significant savings to the property owner, since the fields are not irrigated, and mowing of the fields is kept to a minimum.

As far as I can tell, the fields in HPLs are kept quite natural, with most of the grasses being the usual naturalized exotics such as Bromus inermis, mixed in with natives such as Panicum virgatum and Sorghastrum nutans.

Bromus inermis, which is normally a big part of fields here

I kept wondering whether the HPL concept would fly in some other states. This part of Colorado is lucky because the area is naturally high desert, where open savanna and pure grasslands are natural parts of the landscape.

In a place like New Jersey for example, which does not normally have lots of natural grasslands, any space left untended would soon become a big mess of brambles and forbs and weedy plants, which isn't as "attractive" as prairies. Energy and money would be needed to maintain a "cleaner" look, and this would probably discourage landscapers from exploring possibilities.

I did notice even here in Colorado that parts of some natural fields have a proliferation of weedy looking forbs in them, but on the whole, the system seems to maintain a nice equilibrium of small and medium tall grasses, with some forbs mixed in.

This plus the heavily maintained turfgrass next to it proves that such HPLs are a great alternative to the more boring landscapes with pure turfgrass. 

 Now, that's a "lawn" that I would love to have all year round.

Panicum virgatum, another species that forms part of the field

Letting Your Lawn Grasses Flower

Stenotaphrum secundatum (St. Augustine Grass) flowerhead with orange anthers and purple stigmas

Notwithstanding the growing complaints about lawns, a lawn of turf grass has some aesthetic  qualities. Lawns are clean looking to some people, and they project a sense of ordered structure that a mélange of different plants squeezed together might not.

Paspalum notatum (Bahiagrass) with purple anthers and stigmas

But aside from a few weedy species like Poa annua that thwart the mower's blades by flowering close to the ground, the various turf grass species are kept from showing their full reproductive selves by the regular mowing that homeowners do. This incessant desire to keep the lawn grasses short prevents the grasses from pushing up flowerheads and scattering pollen and seeds to the winds, while making it difficult for homeowners to identify the grass from just their vegetative structures.

Zoysia matrella with tiny spikelike flowerheads

Most turf grasses have relatively tiny inflorescences, a consequence of the fact grasses are wind-pollinated and have no need to expend energy on unneeded colorful petals and sepals. In addition, turf grasses are usually species which have evolved to be grazed, so they eschew tall stalks and flowerheads and keep close to the ground. 

But it is still fascinating to see the usually colorful stigmas and anthers via some magnification, and by setting aside parts of the lawn as temporary no-mower areas, owners can finally see the turf grasses flower, as well as type them more accurately to species.

Eremochloa ophiuroides (centipede grass) with silvery stigmas and purple anthers

So take some time to see what the flowers of your own lawn looks like. Make at least some part of your lawn no-mow until the tiny flowerheads and seedheads rise up to scatter your lawn's grass seeds to the wind.

Say this 5 times fast: Stenotaphrum secundatum!

 A lawn in a lawn right?

But interestingly enough, the species of grass used to create lawns varies widely as one goes from one region to another in the USA.

In our home in New Jersey, our really old lawn (which I inherited from previous owners) is a mishmash of cool season grasses like Poa pratensis (Kentucky blue grass), Fescue spp, and Lolium spp (eg. Perennial Ryegrass). 

By Kevin Thiele from Perth, Australia

In Florida however, we were confronted by completely different species, those more adapted to the warmer weather all year round. In our case, a rhizomatous and stoloniferous grass called Stenotaphrum secundatum, which has the local name St. Augustine grass (and various other common names around the world).

From a distance, the major difference is probably the lighter color of the lawn. But when you actually look closely the change in habit is very obvious. S. secundatum is a creeper - its stolons or aboveground horizontal stems allowing it to "crawl" along the ground like some green hued centipede. This behavior is quite unlike its cool season brethren in the north, which at best have underground rhizomes. 

I was so taken by this creeping behavior that I potted one, set it down on our lanai, and attempted for a short while to see how far it would stretch along the cement floor in its search for soil. It grew by around 5 cm in 12 days before I had to stop the experiment due to eternal circumstances, but I may repeat the experiment again later.  

Potted grass as it crawls out of the pot and starts to search for soil

The composition of the lawn also affects how it is viewed even from far away sometimes. For example, in the image below, the lighter green areas are S. secundatum, while the dark lot is likely Paspalum notatum (Bahia grass). The border between the two species was amazingly straight most times, although S. secundatum seems to have the more pronounced tendency to encroach onto the other territory. In addition, I noticed various other plant species (aka weeds in lawn parlance, haha) had a harder time establishing themselves in the dense masses of culms and blades and stolons that S. secundatum creates. 

Lawns from high up

A third type of turf grass in the community is a very small, fine leaved species used for the golf areas, and the next time I'm there I'll be sure to take a sample and try to ID it. I know some people are quite ambivalent (or even hostile) towards turf grass, but after being in an HOA community that uses various species to populate the landscape, I have started to become quite interested in the ecology of lawn grasses.

More to come on this perhaps.