Instructions for Trial Participants

How to take growth measurements–National Ornamental Grass Trials

These are the measurements which are expected for the trial data collection. Please use ‘National Ornamental Grass Evaluation form-August 2013’ to collect data. Final trial measurements should be taken towards the end of growing season, which will typically be in late August/September. Please post on National Grass Trial blog, with photos.

  • The same person(s) should take growth measurements for uniform data collection.
  • Please see visual guide sheet for photos of data collection measurement diagrams
  • Please take photos of all individual grass cultivars, especially at time of highest ornamental value

1.       Date of spring green up or first growth: Dried vegetative growth and inflorescence should be cut back before growth occurs, cut approximately 4-6 inches or 11-16 cm above the crown.

2.       Height: an average of the highest point, including inflorescence if present

Measure grass height (leaf or inflorescence) at the tallest vertical point (do not straighten up the plant; i.e., droop height) where the bulk of a plant’s mass occurs.

If the plant has only 1 inflorescence and the bulk of the mass occurs in the leafy portion of the plant, measure the tallest leaf height. (If the inflorescence provides a bulk of the mass, then the tallest portion of the inflorescence is measured)

3.       Width: At widest point, does not include lodging. (Lodging=The tendency of grasses to bend over, so that they lie more or less flat on the ground.)

4.       Foliage color: Use Royal Horticultural Society’s color chart if available, or use free online chart from the RHS:  Describe color (Example: RHS-72A, red-purple) as best you can. Also, indicate approx. percentage of plant which is not ‘normal’ green. Example: ‘’P. virgatum ‘Ruby Ribbons’ is  50% red-purple”

5.       Plant form or overall growth habit rating, including uniformity and lodging.

1= 80% or more of the plant is prostrate

2= approximately 66% of the plant is prostrate, or is lodged or is in any way ‘non-uniform’

3=50% lodging or prostrate

4=80% or more of the plant is upright, uniform, very little lodging

5=95% or more of the plant is upright, uniform, attractive, very ornamental, no lodging

6.       Flowering date: Initial date when inflorescence appears.

7.       Floral impact:

1= no impact (no inflorescence present);

2= 25% impact

3= 50% impact

4=75% impact

5=95% impact, very showy

8.       Fall color: note color and date of change.

9.       Self-seeding:  Observe throughout the year:

1=many seedlings near plant

3= some seedlings

5=no seedlings

10.   Winter injury or survival:


3=50% injury

5= no winter injury

11.   Pests: (Note type of injury, i.e., leaf spot, rust, etc.)

1=pest evident and detracting from appearance

3=some pest damage, to 50% of plant

5= no pest

 12. Landscape Impact Rating Scale (from B.Pemberton, Texas A&M)

 1 = Very little or no ornamental value in the landscape.  Growth weak with poor foliage color, high rate of lodging, little flowering (if flowers should be present) and/or high rate of disease or insect damage.

              2 = Below average landscape appearance and value.  Vigor poor with significant problems with plant habit and/or disease or insect damage.

 3 = Average landscape appearance and value.  Vigor good, but with some problems with plant habit, and/or disease or insect damage.

4 = Above average landscape appearance and value with only minor problems with
plant growth habit and disease or insect damage.

 5 = Outstanding landscape appearance and value.  Good vigor, foliage color, and flowering (if flowers should be present), with little or no disease or insect damage.

      13. Comments: Any other noticeable traits not covered above or additional comments about growth  characteristics.   

National Ornamental Grass Trial-measurement diagrams

National Ornamental Grass Trials Evaluation Form-August 2013

3/13jr/mm; edit 8/13                               


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