Posts tagged nitrogen

Overseeding lawns

Richard Jauron, Horticulture Specialist at Iowa State University Extension, offers the following on overseeding lawns:

Healthy, well maintained lawns are attractive landscape additions.  Lawns in poor condition, however, are somewhat unsightly.  The poor condition of a lawn may be due to poor management, heat, drought, diseases, insects or other factors.  In severe cases, the existing lawn may have to be destroyed and a new one established on the site.  Lawns that contain over 50 percent desirable grasses can often be improved by overseeding.  

Overseeding is the sowing of grass seed into an existing lawn.  In Iowa, the best time to overseed a lawn is late summer (late August to mid-September).

Site Preparation

Good site preparation is necessary for successful overseeding.  If possible, identify and correct the problems causing the lawn to decline.  Overseeding may only be a temporary solution if these problems are not corrected. 

To reduce the competition from the established turfgrass, mow the lawn at a height of 1-1/2 to 2 inches.  Successful overseeding also requires good seed-to-soil contact.  Simply throwing or broadcasting seed over the lawn typically results in poor seed germination as much of the seed is resting on the thatch layer or soil surface.  Rakes, core aerators, vertical mowers, and slit seeders can be used to ensure good seed-to-soil contact. 

Overseeding Small Areas

Small areas can be prepared by gently raking the thin spots.  When raking, it’s necessary to break the soil surface without pulling out the existing turfgrass.  After raking, sow the seed by hand.  Then, work the seed into the soil by gently raking the areas a second time. 

Overseeding Large Areas

Large areas can be prepared by using a core aerator.  Core aerators are machines with hollow metal tubes or tines.  They remove plugs of soil when run over the lawn.  To prepare the site, go over the lawn three or four times with the core aerator.  When finished, there should be 20 to 40 holes per square foot.  Apply the seed with a drop seeder.  Afterward, drag the area with a piece of chain link fence or drag mat to break up the soil cores and mix the seed into the soil. 

It’s also possible to prepare the site with a vertical mower.  When run over the lawn, the knife-like blades of the vertical mower slice through the thatch and penetrate into the upper 1/4 to 1/2 inch of soil.  One or two passes should be sufficient.  Afterwards, remove any dislodged debris from the lawn.  Sow grass seed over the lawn with a drop seeder.  Work the seed into the soil by again going over the site with the vertical mower. 

Large areas also can be overseeded with a slit seeder.  A slit seeder makes small grooves in the soil and deposits the seed directly into the slits. 

Core aerators, vertical mowers and slit seeders can be rented at many garden centers and rental agencies.  If you would rather not do the work yourself, many professional lawn care companies can overseed your lawn. 

Post Seeding Care

Keep the seedbed moist with frequent, light applications of water.  It’s usually necessary to water at least once or twice a day.  Continue to mow the lawn at a height of 1-1/2 to 2 inches.  Mow the lawn frequently to reduce the competition from the established turfgrass.  When the new seedlings reach a height of 1-1/2 to 2 inches, gradually increase the mowing height over the next several weeks.  The final mowing height should be 2-1/2 to 3 inches.  Approximately six weeks after germination, fertilize the lawn by applying 1 pound of actual nitrogen per 1,000 square feet.  

When properly overseeded, a thin, scruffy-looking lawn can be turned into a thick, lush lawn in just a few weeks. 

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Sour soil

The following information is from Claire Smith, Linn County Master Gardener:

 

My granddaughter was reading to me the other day and asked me to define “etc.” and eucalyptus”.  That got me to thinking that there have been several occasions where I’ve been a bit embarrassed because I didn’t know the definitions of some gardening words.  Following are a very few of the multitudes of terms.  Acid Soil:  soil with a pH less than 7.0.  Acid soil is sometimes called “sour soil” by gardeners.  Most plants refer a slightly acid soil between 6-7 where most essential nutrients are available.

  • Alkaline Soil:  soil with a pH greater than 7.0, usually formed from limestone bedrock.  Akaline soil is often referred to as “sweet soil”. 
  • Bare Roots:  trees, shrubs, and perennials that have been grown in soil, dug and have had he soil removed prior to sales or shipping.  Mail order plants are often shipped bare root with the roots packed in peat moss, sawdust or similar material and wrapped In plastic 
  • Berm:  a low, artificial hill created in a landscape to elevate a portion of the landscape for functional and aesthetic reasons such as to add interest, screen areas, or improve drainage.
  • Canopy:  the total overhead area of a tree including the branches and leaves.
  • Cold Hardiness:  the ability of a perennial plant (including trees, shrubs and vines) to survive the minimum winter temperature in a particular area.
  • Complete fertilizer:  powdered, liquid or granular fertilizer with a balanced proportion of the three key nutrients-nitrogen (N), phosphorus (P), and Potassium (K).
  • Compost:  decomposed organic matter added to the soil to improve its drainage and ability to retain moisture.
  • Corm:  a modified bulb-like stem.  It is swollen, short, solid and located underground. Crocus and glads are two plants that grow from corms.
  • Cultivar:  a CULTIvated VARiety.  A unique form of a plant that has been identified as special or superior and has been selected for propagation and sale.
  • Deadhead:  to remove faded flowers from plants to improve their appearance, prevent seed production, and stimulate further flowering.
  • Deciduous Plants:  trees and shrubs that lose their leaves in the fall.
  • pH: a measurement of the relative acidity (low pH) or alkalinity (high pH) of soil or water based on a scale of 1 to 14, with 7 being neutral.  Individual plants require soil to be within a certain range so that nutrients can dissolve in moisture and be available to them. 
  • Rootbound (or potbound):  the condition of a plant that has been confined in a container too long.  Its roots are forced to wrap around themselves and even swell out of the container.  Successful transplanting or repotting required untangling and trimming away some of the matted roots.
  • Self-seeding:  the tendency of some plants to sow their seeds freely around the yard.  It creates many seedlings the following season that may or may not be welcome.
  • Slow-acting (slow release) fertilizer:  fertilizer that is water soluble and releases its nutrients when acted on by soil temperature, moisture and/or related microbial activity.  Typically granular, it may be organic or synthetic.
  • Variegated:  having various colors or color patterns.  The term usually refers to plant foliage that is streaked, edged, blotched, or mottled with a contrasting color, often green with yellow, cream or white.

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