Fall Growing Practices for Better Lawns

September 1st, 2009 , Brian Stefl, Landscape Designworks, Inc.

Turf grass plants respond to fall weather by multiplying themselves, deepening their roots, and displaying dark green color.  Growth changes attending turf plants in the fall are largely due to increased rainfall, lower temperatures and abundant sunshine.  These natural growth responses help lawns quickly recover from stress caused by summer heat and drought.  Fall growing practices help nurture the relationship between plant characteristics and the agreeable growing conditions existing during this period. Fall growing practices for lawns commonly include planting seed, mowing, irrigating, fertilizing, core cultivating and controlling weeds. 

 Planting seed

Planting turf grass seed between mid August and mid September yields the fastest germination times, best seedling vigor, and least amount of weed competition.  Seed should be planted directly into soil by hand or broadcast spreading followed by rolling/tamping or by way of a rentable mechanical seeding device called a slice or slit seeder.  High rates of nitrogen and phosphorus applied to the seed bed a couple times in the first 6 weeks of establishment ensures fast aesthetic and functional benefit.  The seed bed should stay moist for 6 weeks and mowing should occur frequently and at a low height beginning when the first seedlings reach 2 inches. 

 Choose seed mixtures based on the lawn’s summer watering and sunlight conditions.  Seed mixtures for most lawn conditions should either be dominated by either Kentucky bluegrass or Creeping red fescue.  Perennial ryegrass should account for less than 20% of a mix to guard against domination of that species which yields a bunchy appearance impossible to overcome without kill off and re-planting.

 Mowing

Turf grass plants are most competitive against weeds and able to produce deep roots when mowing heights are maintained above 3 ½ inches.  Continuing to mow weekly at a 3 ½ inch height through the end of the season helps bolster abundant turf plant density (plants per square foot), spring rooting and resistance to next summer’s likely onslaught of heat and drought.

 Irrigating

Turf grass plants deepen their roots in the fall making water harvesting easier.  Irrigating during this period should be infrequent with deep soakings occurring a couple times each week when rainfall is absent. Irrigating should cease early to mid October in time to allow turf plants to harden down before early cold snaps.  Lean fall watering helps build deep and abundant root systems and prevents infection from pink and grey snow mold.

 Fertilizing

Turf grass plants most efficiently utilize and benefit from nutrient additions made during the fall months.  The single most important fertilizing application of the season should occur mid August through mid September.  An addition of a fertilizer product containing high nitrogen and high potassium at this time stimulates rhizome growth (laterally growing stems) in Kentucky bluegrass and Creeping red fescue while also serving to increase plant density and intensify lawn color.  Fertilizer for this period should contain approximately a 50/50 mix of fast and slow nitrogen sources.

 The second most important fertilizing application of the season should occur just after the last mowing and no later than late November.  An addition of a fertilizer product containing high nitrogen and an increased potassium portion at this time stimulates color, increases photosynthesis and protects against winter stress.   Fertilizer for this period should combine approximately 80% fast acting with 20% slowly acting nitrogen sources.

 Core cultivating

A lawns surface over time becomes compacted or layered with various soil types or organic matter making it incapable of productive movement of water and air into the root system.  This condition is commonly the largest contributing factor to lawn decline. Cultivating the surface with equipment designed to extract and deposit pulled plugs (cores) alleviates poor drainage and airflow promoting exponential rooting and lateral stem growth.  Core cultivating (aerating) should occur on most lawns once a year while lawns planted from sod and those consisting of extremely sandy or clay soil will benefit from the growing practice twice a year or more.  Fall core cultivating should occur during the lawns peak root growth period – early September through early October.  The growing practice should leave core-hole spacing no more than 2-3 inches apart necessitating multiple passes with most types of equipment.  Avoid the practice when soil is saturated from irrigation or rainfall. 

 Controlling weeds

Broadleaf lawn weeds that are perennial in nature survive winter by packing stored energy in the form of sugars into roots and lateral stems.  These underground growth structures become the site of new growth as they deepen and spread in preparation for spring re-growth.  This process begins after a few hard frosts have occurred but before winter sets in.  Applications of sprayed herbicides during this period enter weed leaves and are quickly transported to areas of current new growth – roots and lateral stems.  Dead weed roots and lateral stems resulting from a late fall herbicide application reduces or eliminates the potential of spring re-growth leaving spring lawns largely void of weeds. 

 Some weeds are more difficult to control than others.  Ground Ivy (creeping charlie) is one such weed requiring late fall spraying with a product containing Triclopyr for effective control.  Wild violet can be hampered with the same regimen but might require physical removal for ultimate control. 

Please call us if we can help you to make your lawn look better, live longer and cost less to maintain. Post written by Ben Yost, Farm ‘N’ Garden, Inc.

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