Plan Now for a Beautiful Spring Lawn
It may be hot, humid, hazy August in central Virginia, but now is the time to begin thinking of lawn renovation. Your lawn now is probably in the worst condition of the year due to our hot summers and lack of rain which is why it is called a “transition zone” for cool season grasses e.g. fescue. Yellow, brown, thin, dead spots and fungus are not unusual for this time of the year. However, don’t give up! Fall is the best time of the year to seed/reseed, fertilize and lime, aerate and even sod your yard if desired. First, this is a great time to do a soil test if not done within the last 3 years. That way you will be ready with a plan come September. In the March, 2015 issue of The Garden Shed, Janet Anastasi says a soil test is the best investment you can make for planning purchases of fertilizer and soil amendments. In the September issue there will be a feature article on soil with more details on soil features.
If the ground is not too hard, collect a soil sample by mid-August. Soil test kits are available at your local Virginia Cooperative Extension Office located at 460 Stagecoach Road, just off of Fifth Street Extended in Charlottesville. The samples should only be taken from the lawn, not flower or vegetable gardens or mulched areas. If the front yard looks completely different than the back yard, 2 samples would be a good idea.
Equipment- shovel, trowel, or soil sampler, and a clean plastic bucket. The tools should not be brass, bronze or galvanized because they can contaminate the sample with copper or zinc.
Samples- Dig down 3-4 inches, remove the debris on the top of the sample and place in a dry, clean bucket. Take about 10-20 samples in representative areas, mix the dirt thoroughly removing rocks and twigs and pack in a soil test box to the fill line. Do NOT use wet soil. Allow it to dry if necessary or delay sampling until the ground is drier. Assign a sample ID such as “front yard” to the box and complete the paperwork. The sample can then be sent to VA Tech and the results will be returned by email within 2 weeks. The mailing address and directions will be on the included paperwork. Be sure to indicate on the paperwork that you are sampling a lawn, otherwise you will receive no recommendations for any improvements needed.
Final report-The results will include the pH level, available phosphorus (P), potassium (K), calcium (Ca), magnesium (M), zinc (z), manganese (Mn), copper (C) and iron (Fe) components of your soil. Lastly, recommendations will be made for the amount of fertilizer and lime if needed. The report cannot provide a quantification of N or nitrogen which is in most fertilizer, but recommendations will be included for fertilizer amounts. It is important to know how large your lawn is in square feet to determine the amount of amendments to be added. It is harmful and a waste of money to add too much to the lawn. For help measuring go to http://igrow.org/gardens/gardening/first-step-to-lawn-care-measure-your-lawn/
pH- One of the most important factors for the lawn is the pH. This is a measurement of the acidity or alkalinity of the soil and is a major determining factor if nutrients can be easily absorbed. In our area, the soil tends to naturally be more acid meaning a pH of < 7.0 and usually much lower. An ideal pH for lawns is 6.2. For a detailed explanation of the contents of a soil test report, go to https://pubs.ext.vt.edu/452/452-701/452-701.html.
Core aeration is a recommended cultural practice to maintain and encourage a healthy lawn. It is especially important for compacted, heavily used turf and those with thatch buildup of more than half an inch. Aeration is a process that removes small soil plugs or cores from your lawn. Each core is 1/2 to 3/4 inches wide and 3-6 inches long. Depending on the machine, the holes are about 2-6 inches apart. These finger like cores are deposited on the lawn itself and will disintegrate and filter back down into the soil after it rains. Mingling soil and thatch hastens the decomposition of thatch. The machine can be rented for half or whole days. Going in with the neighbors and renting it for a whole day is helpful.
The Virginia Cooperative Extension agents believe that core aeration benefits your lawn by:
- Increasing the activity of soil microorganisms that decompose thatch
- Increasing water, nutrient and oxygen movement into the soil and carbon dioxide out
- Improving rooting
- Enhancing infiltration of rainfall or irrigation(better drainage)
- Helping prevent fertilizer and pesticide run off from overly compacted areas
For more details on aeration I discussed it in the November issue of The Garden Shed. Go to http://piedmontmastergardeners.org/article/aerating-your-lawn/.
Most lawns do not need complete renovation, meaning starting all over. This is done only when >50% of the lawn is bare or weed covered. Overseeding your current lawn over several years is an easier process, but still a lot of work depending on the size of the yard.
Try to determine why your lawn is failing. This may require some education or even consultation with a professional or the extension office. Consider these possibilities:
- Inappropriate mowing heights
- Too much shade
- Not enough organic matter
- Compaction because of its usage
- Environmental challenges such as too much or too little rain
- Wrong type of grass seed for intended purpose
- Poor drainage
- Nutrient deficiencies including pH extremes
As Dr. Mike Goatley, turf specialist for VA Tech says, “Simply applying seed over the top of an existing turf without any soil preparation usually does nothing more than feed birds and wildlife.” The seed needs to have contact with soil that has been disturbed. Aerating will create plugs that disintegrate helping add loose soil to the area. Watering the lawn prior to aeration may be necessary if the soil is too dry and hard. Additionally rake all exposed areas with a garden rake. No, golf shoes will not be sufficient for aeration! Level uneven areas with topsoil or compost. Add ¼ to ½ inch compost to entire lawn. Add lime as recommended per the soil test. Lime can only be added at a maximum rate of 50 pounds/1000sq ft. every 30 days. Lime will take time to alter the pH but it will not hurt the seed germination to do it now. Delay fertilization for one month.
The 2015-2016 Turfgrass Variety Recommendations list can be found at http://pubs.ext.vt.edu/CSES/CSES-17/CSES-17_pdf.pdf. This represents the joint recommendations of the best cultivars of turf grass variety trials at Virginia Tech and University of Maryland. These will not be easily found in box stores or even garden centers. A turf or landscape supply store may be able to help. At least select one for your specific needs such as shade or sun, drought resistant and always buy certified seed. Certified seed is a guarantee from the seller that you will get the variety listed on the label. For the Charlottesville/Albemarle Virginia area the best adapted turf is tall fescue, bluegrass mixtures or a combination. For areas with full sun use Kentucky bluegrass or hybrid bluegrass but know that this will require more mowing. Fine fescue is best for heaviest shade and tall fescue for moderate shade.
Overseed at a rate of about 2-3 #s of seed/1000 sq. ft. of lawn area (depends on species). Putting too much seed down is detrimental as each seed needs to touch soil. Spreading half the seed in one direction and then spreading the other half at 90 degrees to your first pattern ensures the most uniform coverage. A light raking is recommended to cover the seed. Some then recommend that the seedbed be rolled which sounds like more work to me but the end result may be worth it.
New seed will need to be lightly watered regularly with the goal of not allowing seed to dry out until germinated. This may require multiple waterings per day initially until the seed germinates. Watering can then be slowed down to ½ inch every 2-3 days, unless the weather dictates differently.
The new lawn can be mowed when it is one third taller than the desired height. For example, if the desired height is 3 inches, wait until it is about 4 inches before mowing. Be sure the lawn mower blades are sharp.
Lime can be applied anytime but it takes several months to be incorporated into the soil. It is best applied in the fall. There are two types of lime: ground dolomitic and pelleted. Ground lime releases slowly but lasts 2-3 years. Pelleted is finely ground and then pelleted in a dispersible binder. When water comes in contact with the pellets, they dissolve and then are available. However, it does not last as long, may be needed annually and costs more. It does spread more evenly and creates less dust. Although, I have seen a mixed review on timing of fertilization and lime together, University of Connecticut Agricultural Experimental Station says limestone should not be applied within 2 weeks of fertilizer. They claim that this will avoid a chemical reaction between the two which leads to a loss of N (nitrogen) in fertilizer to the atmosphere.
Lime should only be applied at a rate of 50 pounds/1000 sq. ft. which often means several applications 30 days apart.
By now you must wonder why you ever wanted a nice green lawn, but we are almost finished. Why fertilize? Can too much be harmful? How do I calculate how much to put on?
Yes, fall is the optimal time of the year to fertilize cool season turf grass (e.g., Kentucky bluegrass, tall and fine fescues). The advantages of fall fertilization are increased density, increased root growth, decreased spring mowing, improved fall-spring color, decreased weed problems, increased drought tolerance, and decreased summer disease activity. Cooler temperatures and shorter days provide ideal conditions to maximize root growth and food storage prior to winter. Proper fertilization will help provide quality turf when spring arrives. However, Virginians often overuse fertilizer which can negatively impact surface and ground water quality.
Without the proper nutrients your lawn will gradually thin and weeds will invade. Healthy lawns have less disease, fewer insect and weed problems. If you have a healthy stand of grass, there is less chance for nutrient and soil runoff to surface waters.
That being said, the amount of fertilization, lime and watering depends on the individual and the amount of maintenance you are willing to dedicate.
High-maintenance lawns are characterized by vigorously growing plants. For best results these lawns are watered during the summer to maintain green growth. Clippings left on the lawn gradually decompose and reduce the need for fertilizer.
Low-maintenance lawns do not commonly receive watering (other than rainfall) during the summer months and grass growth is minimal during hot, dry periods. Clippings are usually left on the lawns.
Plants need carbon, oxygen, and hydrogen. That cannot be gotten from fertilizer. They come from the atmosphere. Fertilizer is only effective if air and water get down to the shoots and roots, thus the need for aeration. Nitrogen (N), phosphorus (P) and potassium (K) must be added to the soil. Calcium (Ca) and magnesium (Mg) are obtained by adding lime.
There are 2 types of fertilizer:
- Water soluble-in the form of ammonium nitrate, ammonium phosphate or urea.
- Slow release-in the form of methylene urea, sulfur coated urea, urea formaldehyde and heat treated sewage sludge.
All fertilizer packages must have three numbers present on the package such as 10-10-10 or 16-4-8. These numbers represent the percentage by weight of nitrogen or N, phosphorus or P and potassium or K. So a 50 pound bag of 10-10-10 contains 5 pounds each of nitrogen, phosphate and potassium (calculated as 50 pounds times 0.1 or 10% equals 5 pounds). These three elements are the primary minerals needed for plant growth. The package also details the percentage of other nutrients included such as iron and sulfur.
NITROGEN (N) Fall fertilizer with appropriate amounts of N lead to better turf next spring, including improved turf density, color, above ground vegetative growth and food storage. Nitrogen is absorbed by plants from the soil in the greatest quantities.
PHOSPHORUS (P) The second number on the bag is phosphorus which is essential in all phases of plant growth, most notably root growth which takes place over fall and winter.
POTASSIUM (K) Also known as potash, potassium is essential for plant growth and plants take large amounts from the soil. The word potash goes back to colonial days when wood and other organic materials were burned in pots for the manufacture of soap. The ashes were rinsed with water, collected and allowed to evaporate. The residue was largely potassium salts. Today potassium is mined from deposits deep in the earth. Plants use as much potassium as they do nitrogen which is three to four times the amount of phosphorus used.
In general lawns respond better to fertilizer ratios high in nitrogen. However, about 1 pound of N per 1000 sq. ft. should be applied in a single application when using water soluble nitrogen. Applications should be distributed at a minimum of 4 weeks apart from September through November. However, slow release fertilizers may be used in greater quantities (1.5 pounds/1000 sq. ft.) without the threat of burning the grass. Thus, I recommend using the latter. It is also called water insoluble nitrogen and says such on the bag (WIN).
The following program was developed by the Virginia Cooperative Extension to help homeowners know how many pounds of nitrogen to apply each month in the fall depending on the quality of lawn desired. As with so many things in life, we all want high quality lawns; but we have to balance our wants with the money and time we’re willing to invest.
|Water Insoluble Nitrogen(WIN) Application By Month|
|Quality Desired||Aug 15 to Sept 15||Oct 1 to Nov 1||May 15 to June 15|
|———————-lbs. N/1000 sq. ft. ———————-|
|High||1.5||1.5||0 to 1.5|
This is the part that confuses many because it involves math. If you have a fertilizer such as 10-10-10 and want to add 1.5 pounds/1000 sq. ft. of Nitrogen, take the first number of 10 and divide by 1.5. 10/1.5 = 6.66. If you have a 1000 sq. ft. of lawn, then you would round it up to 7 pounds of fertilizer on the total lawn. If you have 5000 sq. ft., you would use 5 times that amount or 5 X 7 =35 pounds.
How to apply
It is important to uniformly apply fertilizer containing nitrogen. Lack of uniformity results in streaking or different shades of green turf in the lawn. Drop type or rotary type spreaders are best to use. When using drop type spreaders, be sure to overlap the wheel tracks since the fertilizer is distributed between the wheels. These spreaders can be difficult to maneuver around shrubs and trees. Rotary spreaders usually give a better distribution because they cover a bigger swath. Apply half the material in one direction and the other half in a perpendicular direction. Avoid application to any non-turf areas such as sidewalk, patios, driveways or roads where it may enter the water supply. Blow or sweep any fertilizer away. Do not hose it. Avoid applications if weather forecasts call for heavy rainfall. Having a 1/4 inch of rain after application is an ideal way to move fertilizer into the soil.
Good luck on your September venture to improve your lawn, using all of the additives at the right amount that is environmentally safe and hopefully with the knowledge to teach others.
“Liming and Fertilizing Established Lawns”, Rathier, Thomas, http://www.ct.gov/caes/cwp/view.asp?a=2815&q=376936
“ Fall Lawn Care”, Goately, J.M., http://www.pubs.ext.vt.edu/430/430-520/430-520.html
“Virginia Turfgrass VarietyRecommendations,” Goatley, J.M. http://pubs.ext.vt.edu/CSES/CSES-17/CSES-17_pdf.pdf
“ First Steps to Lawn Care: Measure Your lawn”, Chalmers, David, http://igrow.org/gardens/gardening/first-step-to-lawn-care-measure-your-lawn/
“Explanation of Soil tests”, Maguire, Rory, https://pubs.ext.vt.edu/452/452-701/452-701.html
“Aeration”, Bolton. N, The Garden Shed , Vol. 1, #11, 2015, http://piedmontmastergardeners.org/article/aerating-your-lawn/.
“Fertilizing lawns”, Rosen, C.J., B. P. Horgan, and R. J. Mugaas, http://www.extension.umn.edu/garden/yard-garden/lawns/fertilizing-lawns/
“Lawn Fertilization in Virginia”, Goatley, J.M , http://pubs.ext.vt.edu/430/430-011/430-011.html
“Fall fertility strategies for Virginia’s home lawns”, Goatley, J.M., http://www.sites.ext.vt.edu/newsletter-archive/cses/2008-09/FallFertility.html
“Home lawn fertilization in Virginia: Frequently asked questions”, Chalmers, David, http://pubs.ext.vt.edu/430/430-003/430-003.html