Berks County Cooperative Extension -

TURFGRASS - SEED SELECTION

Grass categories.

Turfgrasses can be broken into two broad categories: warm-season grasses and cool-season grasses. Except for zoysia grass (Zoysia Japonica), a warm-season grass that has sufficient hardiness to survive in southern-most areas of Pennsylvania, the grass species appropriate for Pennsylvania are cool-season grasses. As the term suggests, cool-season grasses display their greatest growth during the spring and fall, and may enter a semi-dormant state during periods of high temperatures or under drought conditions.

Species and characteristics.

SPECIES	HEAT/DROUGHT TOLERANCE	SHADE TOLERANCE	OTHER
Kentucky Bluegrass (Poa Pratensis)	Very good	Poor	Recovers quickly from heat and drought stress
Rough Bluegrass (Poa Trivialis)	Moderate	Excellent	Light green color - forms patches
Perennial ryegrass (Lolium Perenne)	Heat - very good Drought - moderate	Poor	Seed with endophytes (beneficial fungi) enhances disease resistance
Fine fescues (Festuca Spp.)	Heat - moderate Drought - very good	Moderate	Hard fescue (festuca longifolia) difficult to establish, but highly drought tolerant
Tall fescue (Festuca Arundinacea)	Excellent	Moderate	Deep root system - most drought and heat tolerant cool-season grass

Seed selection criteria.

It is important to purchase high quality seed that is suitable for site conditions. Poor quality seed may not germinate properly and may contain unacceptable percentages of weed seeds and undesirable grass species. An effort to establish a lawn under partial shade conditions without considering the shade tolerance of various species of grass and selecting an appropriate mix is likely to fail. Before purchasing seed, take care to study the label and make special note of the following:

The species and varieties of turfgrass listed in order of predominence.
The percentage by weight of pure seed of each species and variety.
Germination percentage and the date of the germination test.
Percentage by weight of weed seed. This number should not exceed 1%. Good quality seed contains no more than 0.5%.
Percentage of undesirable species and varieties of turfgrass, such as timothy, meadow fescue, annual ryegrass or clover. Seed of high quality contains no undesirable grasses.
Percentage of inert material, such as chaff or other foreign ingredient. Except where fertilizer coatings or pellets are added to assist in seed establishment, this number should not exceed 15%.

Seed mixtures.

Turfgrass is most commonly sold as a mixture or blend of species and varieties. Planting a diverse mixture of species and varieties makes the resulting stand less likely to be devasted by disease, heat stress or drought stress. Site conditions, especially sun exposure levels and drainage, must be considered before selecting a mixture.

A mixture for a sunny, well-drained site will typically consist primarily of several varieties of Kentucky bluegrass together with varieties of perennial ryegrass and fescue.

A mixture for a well-drained site in partial shade will typically consist of approximately equal percentages of fine fescues and Kentucky bluegrass together with perennial ryegrass.

Dense shade and temporary erosion control.

In the following cases, planting a mixture of grasses is not recommended and a specific species should be planted:

If the site is well-drained and is in heavy shade, fine fescues should be planted.
If the site drains poorly and is in heavy shade, rough bluegrass should be selected.
Where a site must be temporarily covered for erosion or dust control, either annual ryegrass or Italian ryegrass should be used.

Source: The Penn State Master Gardener Manual
Document created: 15 December 1999; Revised: 3 March 2001