Winter Lawns Gone a-Rye

Winter Lawns Gone a-Rye

Ryegrass can use twice as much water as St. Augustine and it can weaken other grasses. So unless you enjoy spending money on your lawn during the winter — and possibly having a sparse lawn next spring — don’t plant winter rye.

Every year we get requests for irrigation variances or advice on ryegrass. We pleasantly, but firmly say no to any type of irrigation variance. And our advice for ryegrass is: never touch the stuff.

Of course, golf courses over-seed (apply seed on top of existing grass) each and every year, often to the detriment of their existing grasses. It’s their business model to have verdant tee boxes, fairways and greens. But that doesn’t have to be your model.

In fact, unless you enjoy spending money on your lawn during the winter and your sewer bill throughout the following year, then you should consider another model.

What is ryegrass?

Ryegrass (Lolium spp) is classified as a cool season, temporary grass. In other parts of the country, it may be grown together with bluegrass and fescue during the spring and summer.

In Texas, we don’t begin to over-seed until the nights are consistently in the low 60s and daytime temps don’t exceed the high 70s. Generally this is early November.

To initiate germination, ryegrass must have cool temperatures, sun and moisture. The latter generates the requests for irrigation variances if we are in Drought Stages. Because of the limited (if any) benefit to the environment or community, we firmly say no.

There are several different species and selections, but only two are commonly used for turf grass: Italian (L. multiflorum) or annual ryegrass, and perennial (L. perenne) ryegrass. Generally speaking, the Italian is used for agricultural and erosion purposes, whereas the perennial more frequently for landscape purposes, but this is not mutually exclusive. Elbon rye is an entirely different species (Secale cereale) and is used for wildlife feed and cover, as well as for home gardening as an organic method of capturing nematodes.

“Perennial” and “annual” are relative terms. Italian, perennial and elbon ryegrass are all temporary in Texas. As the weather approaches the mid-80s, ryegrass begins to wither away regardless of species.

Why do we view it with disdain?

Putting aside the esoteric arguments of growing a non-native species during a season in which all of nature is dormant, it’s also not a good idea to apply excessive amounts of water on turf that will die in April and May. The warm season grasses, i.e., Bermuda grass, St. Augustine grass and zoysia, go dormant to semi-dormant in the winter and require little to no supplemental water. Not so with ryegrass — it may require twice as much water as St. Augustine if the winter is dry. Some homeowners may even fertilize this ephemeral grass.

Depending on the weather, ryegrass may also have a detrimental effect on other grasses. A cool wet spring will encourage ryegrass to the detriment of Bermuda grass, thereby delaying its early growth. If this occurs over several years, the warm season Bermuda grass may never recover.

There is also some evidence that ryegrass, like other species in the Poa grass family, produce allelopathic chemicals that inhibit growth or are toxic to other grasses. In combination, weather and allelopathy rapidly weaken and thin the existing turf and come April, the homeowner is left with mostly bare dirt. Golf courses frequently have to re-sprig the tees and fairways every 3 to 6 years because the ryegrass has weakened the Bermuda grass to such an extent as to deplete the population.

An indirect, but notable detriment of ryegrass is that during the months it’s growing and requiring irrigation is the same time that SAWS is determining your sewer fee for the following year. It’s called winter averaging and it monitors the amount of water you use during three complete billing cycle from mid-November to mid-March. No logical homeowner would water plants or lawn during this time since this would cause their sewer rates to rise significantly.

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Mark Peterson

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Mark Peterson

Mark A. Peterson is a conservation project coordinator for San Antonio Water System. With over 30 years of experience as an urban forester and arborist, Mark is probably the only person you know who actually prunes trees for fun. When not expounding on the benefits of trees and limited lawns, you’re likely to find him hiking San Antonio’s wilderness parks or expounding on the virtues of geography and history to his friends.