Bob Mugaas, University of Minnesota Extension Educator
This is the third and final article in a series of articles related to choosing and selecting the best MN adapted lawn grasses for this area. This last topic will address the topics of what to do when you can't locate the particular grass varieties you've identified, how to read a grass seed label to know what you're really buying and some suggestions for the kind of grass seed mixes to use in various locations around our home landscapes. The previous posts are listed here:
Series: Choosing and selecting the best MN adapted lawn grasses
Tips for selecting the best available grass seed varieties
Photo 1: Kentucky bluegrass seed sold in bulk. Karen Jeannette.
Selecting and then finding specific varieties of grass seed is not always as easy as you might think. Unlike the relative ease of finding your favorite tomato or marigold varieties through seed catalogs or the internet, looking for specific grass varieties can be much more challenging. It can be quite frustrating to go to a local garden center expecting to find at least some of your particular grass varieties but not see one of them listed on any of the grass seed labels carried by that retail outlet. Instead there are varieties listed that are completely unfamiliar to you. So, what's a person to do?
First, it's important to remember that not all varieties from a seed grower/supplier available in the marketplace will have gone through one of the state and/or national evaluation programs mentioned in last month's article. Indeed, seed growers and some supply companies will have also conducted their own independent variety research. From that research, they will make determinations about what varieties would be suitable for use in mixes to be packaged and sold in the retail or wholesale market.
Second, availability of particular varieties can also be a function of supply and demand characteristics. In some cases, the demand for a particular variety or varieties for use in larger wholesale markets (as well as for sod production) can exceed the supply of those varieties leaving little or none left to be packaged into the homeowner available quantities. In other instances, the availability of seed from particular varieties may be quite low for that year due to a number of possible causes (e.g., poor seed production, adverse weather conditions, etc.) Once again, those particular varieties may not show up either in commercial wholesale mixes or in the seed mixes available at local garden centers or retail outlets.
Finding recommended grass varieties, or the next best thing
So, that still leaves us with the question of "What's a person to do when they can't find the particular varieties they've identified?" One thing that can be done is to jot down the names of the varieties that are listed and go back to the resources mentioned in last month's blog and see if you can find anything about those particular varieties. As with many other things that we purchase, cheaper prices can mean lesser quality. The same would also be true for purchasing grass seed. In general, high quality, 'clean' seed will generally cost more but will almost always provide better results. Staying with reputable, highly regarded name brands of grass seed is usually a good first step even though the specific varieties you were looking for don't seem to be contained in the packages. In other words, the suppliers will most likely still try to provide good quality cutivars that will in turn help the end user, you and me, to achieve good results with their seed mixes. It's also important to remember that seed cost is usually going to be the least expensive item relative to the work and preparation needed to ensure the conditions necessary for successful seeding. Buying cheap, poor quality seed, can jeopardize a project's success no matter how careful all of the preparation work might have been done.
Interpreting the grass seed label
The next logical question one might be asking is "How can I tell if I'm getting both good value and quality in a seed mixture?" That question can best be addressed by examining the different parts of a grass seed label for information that can shed some light on grass seed quality.
Determining what is high quality seed need not be that difficult. Purchasing high quality seed can be easier if you understand a few basic terms on the grass seed label. Figure 1 is a fictitious grass seed label that will be used to discuss the various components of a label. All labels must provide information about the grass seed purity, its germination potential, crop seeds present, weed seeds present, noxious weeds present, and inert components in the package.
Much of the grass seed available in Minnesota comes from the west coast states where climates are most favorable for seed production. However, the very northern reaches of Minnesota are also home to a number of large, well established grass seed production farms. Seed from that area is also available through various outlets in Minnesota. Below Figure 1 is a list of terms you will find on grass seed labels and what they mean.
Terms Found on Grass Seed Labels
- Lot number. This identifies the larger seed lot from which this particular seed came from. If there are issues related to the purity or growth of this mix, the lot number can be very important in tracing back to where problems might have originated.
- Test date (month/year) It is always important to buy 'fresh' seed, that is, seed that has been tested within the year when it is purchased. This information tells when the seed was tested and determined to have the characteristics described further on in the label. It is also a useful date when one is trying to determine how long a particular bag or box of grass seed might have been stored and whether it will still grow or not. In general, it is usually better to buy new, fresh seed if more than two or three years old. This will be especially true if the seed has been stored anywhere else other than in cool to cold, dry storage. In most cases storage in garages or basements will not provide the necessary storage conditions to retain good seed viability. Again, in the bigger scheme of things and relative to the seeding preparation investment, the purchase of fresh, good quality seed is likely to be the least expensive part of the project. Bottom line: Always purchase and use fresh seed!
- Variety These will be the names (when possible) of the actual turfgrass varieties contained in the mixture. In some instances, you will notice a generic term for a species of grass but no specific variety listed. For example, you might see the term 'creeping red fescue, VNS'. The VNS indicates 'variety not stated'. In other words, you know that you are getting a percentage of creeping red fescue but not which specific variety it may be. One shouldn't necessarily consider the term VNS to mean that the grass contained in the mix is a bad grass variety. There could be a number of valid reasons for not being able to list a particular variety. In most cases though, good quality seed mixes will usually try to list specific varieties whenever possible.
- Purity (Pure seed) is the percent by weight of pure seed, crop, weed, and inert ingredients in the package. These percentages added together should total 100 percent. Purity is concerned only with quantity, not quality. That is, not all seeds present in the package are capable of growing. To determine the seed that will actually grow or what is known as pure live seed, the percentage purity should be multiplied by the germination percentage. In this example, 31 percent by weight is Kentucky bluegrass (purity). The germination percentage for that variety of Kentucky bluegrass is 80. If one multiplies the purity value times the germination value you will determine how much of the seed will likely grow (under favorable conditions). When carrying out this calculation you will come up with a value of 24.8%. In other words, of the 31% Kentucky bluegrass contained in the mix, 24.8% of it actually has the capacity to germinate and grow. It should be apparent that you should always seek to purchase the highest purity of grass seed compared to the other contents and the highest germination percentages as possible.
- Germination is the percent of pure seed that will germinate and grow in an ideal laboratory environment during a prescribed length of time. Since field conditions rarely duplicate these laboratory conditions, it is especially important to purchase seed with the highest germination percentage possible. As noted above, this is the percentage used to determine pure live seed.
- Crop is the percent by weight of seeds normally considered to be grown as an agricultural crop such as grain. This can include other types of grasses that may be undesirable in a lawn. This percentage should be as close to zero as possible.
- Weeds refer to the percent by weight of all seeds in the package that are not otherwise listed in pure seed or crop. It is not required to identify these weeds or how many there are since this is on a percent by weight basis. For example, one or two large seeds of a weed would pose no particular threat to the new lawn. However, even a small percent by weight of very small seed could account for thousands of weed seeds distributed over the area. This percentage should always be as low as possible.
- Noxious weeds are listed as the number per pound, not the percentage per pound. Noxious weeds are weedy plants considered by individual states to be very difficult to control and that could pose hazards to both humans and livestock. While this is often more of a problem in farm crop seed, one should always purchase grass seed without the contamination of any noxious weeds.
- Inert is the percent of material contained in the package that will not grow under any condition. Broken and damaged seeds, chaff, and empty seed hulls are just some of the more common inert material included. Obviously, this percentage should be as low as possible.
First Things First: Right Grass Seed - Right Place - Right Function
Photo 2: Side-by-side comparison of Kentucky bluegrass and fine fescue grass species. Bob Mugaas.
The final information in this article is intended to provide some help in choosing a particular mix of grass seed for particular areas and uses in our yards.
- Avoid the temptation of a one-seed-mix-fits-all approach to purchasing grass seed for your property.
- Pay special attention to site differences that may require a different mixture of seed to perform well. The most obvious of these conditions is for one area to be shady while the other part of the yard is in full sun.
- It may be necessary to choose multiple grass seed mixes for the same residential site in order to have the best adapted grasses planted in the different site conditions. Below is a guide to a number of possible grass seed mixes to fit various needs.
- Choosing the right plant for the desired location is of utmost importance for long-term plant health.
- Match the intended use of the lawn area with the proper types of grasses when choosing turfgrass varieties, blends or mixes. See below for site examples to help you match appropriate turfgrasses with the intended site and function.
Site Examples: Matching lawn site and function to seed varietiesSite1:
Full-to-partly sunny conditions with minimal traffic or wear, low-to-moderate inputs intended.
- 60% to 70% Kentucky bluegrasses, 20% to 30% fine fescues, ~10% perennial ryegrass.
Full-to-partly sunny conditions with moderate-to-high levels of traffic and/or wear, moderate-to-high inputs required for rapid recovery:
- 75% to 85% Kentucky bluegrass, ~15% to 20% perennial ryegrass.
Photo 3: Area well suited to Kentucky bluegrass fine fescue combinations such as those for site examples #1 or #3.Karen Jeannette.Site 3:
Shaded for a portion of the day or receives partial shade all day with minimal traffic or wear, primarily a dry shade:
- 65% to 75% fine fescue; 25% to 35% Kentucky bluegrass (shade tolerant cultivars); ~10% perennial ryegrass.
Shaded for a portion of the day or receives partial shade all day with minimal traffic or wear; a somewhat moist shade:
- <30% to 40% fine fescue; 25% to 35% Poa trivialis, 20% - 30% Kentucky bluegrass (shade tolerant cultivars) ~10% - 15% perennial ryegrass.
Full sun-to-very light shade, little to no inputs intended
- 70% to 85% fine fescues; 10 - 20 % common Kentucky bluegrass; 5 to 10% perennial ryegrass.
Notes about using Ryegrass (Lolium perenne) and Roughstalk bluegrass (Poa trivialis
) species in grass seed mixes:
- Be a little cautious when adding perennial ryegrass to a mix. Research has shown that a 50/50 mix of Kentucky bluegrass to perennial ryegrass results in a stand that may be dominated by perennial ryegrass even though there are many more seeds of bluegrass than perennial ryegrass in the mix.
- Because of the seedling vigor of annual ryegrass, it is sometimes used in general-purpose seed mixes; but almost never in mixes for "elite" or "premium" turf.
- Note that the bluegrass species, Poa trivialis, sometimes referred to as roughstalk bluegrass, is better adapted to shadier more moist conditions and usually becomes the dominant species over time in that environment. However, because of the potential aggressiveness of Poa trivialis under favorable growing conditions, some people prefer to avoid using it even though it is well adapted to those conditions.
Hopefully, this article along with the other two previously published articles, Know Your Minnesota Lawn Grasses (http://blog.lib.umn.edu/efans/ygnews/2010/02/how-well-do-you-know-your-minn.html) and So what are the best grass varieties? (http://blog.lib.umn.edu/efans/ygnews/2010/03/so-what-are-the-best-grass-var.html), you'll get a good start on selecting and purchasing the best adapted, highest quality grass seed for your particular situations.