One of the things European colonists brought with them to America was the love of lawn. That's why traditional landscaping in this country includes large expanses of grass. This approach is fine in the eastern United States, with its high rainfall, but in Denver's semi-arid climate many grasses need a lot of supplemental irrigation to stay lush and green. So to avoid wasting water outdoors, grass should be limited to areas that need to be useful lawn.
For those areas that need to be turf, there are two key essentials.
1. Establishing Your Lawn
For those areas that need to be turf, there are four steps to establishing a lawn:
Step 1: Selecting the right grass
There are many varieties of turf grasses. Before choosing the best grass for your location and needs, it helps to know a little about grasses in general. To begin with, grasses are either cool-season or warm-season.
Cool-season grasses grow fastest in spring and tend to go partially dormant in the heat of the summer. In the Denver area, cool-season grasses normally start to turn green in late March and stay green until November.
Warm-season grasses green up around mid-May, grow fastest in summer, and go dormant with the first hard frost, usually in early October. They tend to have a light tan color while dormant.
Grasses are also categorized as either sod-forming or bunch grass. A sod-forming grass will spread, eventually forming an interwoven "mat" of grass. Bunch grass will not spread — each grass plant remains separate from its fellow plants.
There is no such thing as the "perfect" grass — every grass species has its good and bad points. Know your turf to help you select the best grass for your particular situation. Also check with your landscape professional for other turf options.
Step 2: Preparing the soil
Along the Front Range, top soil is typically one of two kinds: heavy clay or sandy. Neither kind is ideal for turfgrass. New construction sites face a greater problem, since most of the existing top soil is removed during the construction process and the soil left behind is compacted by construction traffic.
To perform well, turf needs a minimum of four to six inches of loose, amended soil. Lack of initial soil preparation is a major reason for subsequent lawn failure.
To prepare the soil for seed or sod, do the following:
- Clear the site of any debris, stones, etc. If there is existing turfgrass that will be replaced, either use a sod cutter to remove the turf or use a non-selective herbicide to kill it.
- Eliminate weed problems prior to seeding or sodding.
- Grade the area to eliminate any drainage problems.
- Apply a "starter fertilizer" that contains nitrogen and phosphorus, using the recommendations for the particular product.
- Add one to two inches of soil amendments — such as compost, sphagnum peat or aged manure — and rototill to a depth of six to eight inches or as deeply as possible. Three cubic yards of amendment will cover 1,000 square feet to a depth of one inch.
- Finish grading the site.
Step 3: Seeding or installing sod
To seed a lawn, sow the recommended pounds of seed per 1,000 square feet uniformly across the area. For more uniform coverage, seed in two directions: north-south and east-west, using half the allotted seed in each direction. After seeding, lightly rake the seed into the soil, being careful not to go too deep. If desired, cover with a light mulch of straw or sphagnum peat moss. Finally, use a roller to firm the soil surface.
To install sod, start with the longest straight line (i.e. along a driveway or sidewalk). Push ends together tightly, but avoid stretching the sod. Stagger the end joints in each row of sod, as if you were laying brick, and try to avoid leaving small strips at outer edges.
After laying the sod, use a roller to ensure good soil contact and level out any uneven spots, then water thoroughly.
Step 4: Watering the new lawn
A newly-seeded lawn must be kept moist, but not saturated, until the seeds germinate. Depending on the weather and site conditions, this may mean watering for a short time several times a day. As the grass begins to grow, reduce the frequency of watering. After four to six weeks, watering should be reduced to the amount recommended for an established lawn.
New sod must be watered enough to ensure that the soil beneath the sod stays moist without becoming waterlogged. Water twice a day (early morning and late evening is preferable) for the first week, and once a day for the second week. At this point roots should be established in the new soil and watering can be reduced to the amount recommended for an established lawn.
If you have an automatic sprinkler system, be sure to reprogram it at this point to water based on the ET (evapotranspiration) rate.
2. Know Your Turf
Below are descriptions of the seven most common turf types in Colorado.
Blue Grama (Bouteloua gracilus)
A warm-season, bunch grass with flat blades one to two millimeters wide; color is blue-green; texture is fine and soft during periods of active growth; state grass of Colorado.
Mature Height: 6 to 18 inches; mow to 2 1/2 to 3 inches or leave unmowed to allow development of attractive seed heads.
Watering: 1/2 to 3/4 inch every two weeks during hot, dry spells.
Sun/shade: Likes full sun, poor to fair shade tolerance.
Traffic: Fair tolerance to traffic during periods of active growth.
Planting: Seed only; sod not available. In early May to late July, seed two to three pounds per 1,000 square feet of lawn, or as instructed by seed supplier. Best varieties include Hachita, Lovington and Alma.
Advantages: Attractive, requires minimal water and fertilizer once established, won't invade flower or vegetable beds. Good for sunny areas such as slopes where foot traffic is minimal. Very heat and drought-tolerant, goes dormant when stressed and can stay dormant for extended periods.
Disadvantages: Not very traffic-tolerant during dormancy (October – May), weed control can be a problem, seed is expensive, doesn't perform well as a lawn above 6,500 feet elevation.
Crested Wheatgrass (Agropyron cristatum)
A cool-season, bunch grass with medium blades; color varies from light green to blue-green; texture is soft.
Height: 12 to 30 inches, mow to three inches.
Watering: 3/4 to 1 inch every week during hot, dry spells.
Sun/shade: Tolerates both sun and shade.
Traffic: Fair tolerance to traffic.
Planting: Seed five pounds per 1,000 square feet of lawn. Not available as sod. Planting season is mid-March to early June and mid-August through October. Avoid planting during the heat of summer. Turf-type varieties include Ephraim, Fairway, Hycrest and RoadCrest.
Advantages: Excellent tolerance of heat, cold and drought, low fertility requirement. Goes dormant quickly under drought conditions, and is equally quick to recover from drought dormancy.
Disadvantages: Although tolerant of drought and low fertility, needs regular fertilization and supplemental irrigation to look its best, bare spots will need to be reseeded, doesn't form a dense sod so weed invasion may be a problem.
Kentucky Bluegrass (Poa pratensis)
A cool-season, sod-forming grass with fine blades; color varies by variety from medium to very dark green; texture is fine and soft.
Height: 18 to 24 inches; mow to 3-4 inches. May need less water in shade or well-amended soil, or if property owner will accept less than optimum appearance.
Watering: 1 1/4 to 1 1/2 inches every week during hot, dry spells.
Sun/shade: Likes full sun to light shade; some varieties such as Bristol, Glade, Nugget and America tolerate shade better than other varieties.
Traffic: Good tolerance to traffic, some varieties more so than others.
Planting: Using a named variety or a blend of named varieties, seed three to four pounds per 1,000 square feet of lawn, or as instructed by seed supplier. Seeding season is mid-March to early June, and mid-August through September. Avoid seeding during the heat of summer. Commonly available as sod; sodding can be done any time of year, if the ground is not frozen and can be properly prepared, and if the sod can be harvested. However, the best times to install sod are spring and fall.
Advantages: Attractive, high quality turf with good traffic tolerance. Sod is relatively inexpensive and readily available. Good for yards with children or pets because it has a root system that allows it to fill in bare spots. Goes dormant when drought-stressed, can survive several months of drought. Some varieties more drought-tolerant than others.
Disadvantages: Requires regular supplemental irrigation, some disease and insect problems, will invade flower and vegetable gardens, performs best with regular fertilization.
Buffalograss (Buchloe dactyloides)
A warm-season, sod-forming grass with fine blades; color is blue-green, texture is fine and soft during periods of active growth.
Height: Four to eight inches; mow to 2 to 2 1/2 inches or leave unmowed.
Watering: 1/2 to 3/4 inch every 2 weeks during hot, dry spells.
Sun/shade: Likes full sun; poor to fair shade tolerance.
Traffic: Fair to good tolerance to traffic during periods of active growth.
Planting: Seed, sod and plugs available. In early May to late July, seed two to three pounds per 1,000 square feet of lawn, or as instructed by seed supplier. Use "treated" seed for better germination. A few turf-type varieties available as seed include Tatanka, Topgun, Cody, Plains, Bison, and Sharp's II. Some of these may also be available as plugs or sod. Other turf-type varieties sold only as sod or plugs are 609 and Legacy. Legacy seems well-adapted to the Front Range; 609 is only good for protected, warmer areas. Sodding can be done as late as early August.
Advantages: Attractive, requires minimal water and fertilizer once established. Good for sunny areas such as slopes where foot traffic is minimal. Few insect or disease problems, low fertility requirement. Very heat and drought-tolerant, goes dormant when stressed and can stay dormant for extended periods.
Disadvantages: Not very traffic-tolerant during dormancy (October – May), weed control can be a problem, more prone to weed invasion when over-fertilized, stolons will invade vegetable and flower beds, doesn't perform well as a lawn above 6,500 feet.
Turf-Type Tall Fescue (Festuca arundinacea)
A cool-season, bunch grass with wider blades; color varies by variety from medium to dark green; texture varies from soft to medium coarse.
Height: 24-36 inches; mow to 3 inches.
Watering: 3/4 to 1 inch every week during hot, dry spells. If planted in heavy clay soil that prevents development of long root system, may require as much water as Kentucky bluegrass.
Sun/shade: Likes full sun to moderate shade.
Traffic: Good tolerance.
Planting: Using a named variety or blend of named varieties, seed six to eight pounds per 1,000 square feet of lawn, or as instructed by seed supplier. Planting season is mid-March to early June, and mid-August through September. Avoid planting during the heat of summer. Also available as sod, but may be hard to find.
Advantages: Attractive, does well in shade, has few disease or insect problems, won't invade flower or vegetable beds; lower fertility requirements.
Disadvantages: Requires regular supplemental irrigation. Because of the fibrous root system, bare spots will need to be reseeded. Wider blades may shred if mower blades are dull.
Perennial Ryegrass (Lolium perenne)
A cool-season bunchgrass with medium to dark green glossy blades.
Height: 10 to 24 inches, mow to 2 1/2 to 3 inches.
Watering: 1 1/4 to 1 1/2 inches per week during hot, dry spells
Sun/shade: Poor to fair shade tolerance; prefers full sun.
Traffic: Good tolerance; sometimes used alone or mixed with Kentucky bluegrass for sports fields.
Planting: Using named varieties, seed six to eight pounds per 1,000 square feet. Planting season is mid-March to early June, and mid-August through September. Avoid planting during the heat of summer. Not available as pure sod, but may be mixed with Kentucky bluegrass to form a sod.
Advantages: Germinates and establishes quickly from seed; glossy, attractive blades. Tolerates foot traffic.
Disadvantages: Poor drought tolerance; during cold, dry winter may die. Dull mowers may shred grass blades.