Bold items are the real positive qualities for each grass

Green colored item are positive and red items are negative aspects of each grass

Fescues have the unusual talent of being able to grow in dry shade.(American-lawns) The fine leaf fescues are the most shade tolerant of all the lawn grasses. Traditionally, fescues are used in mixes with Kentucky bluegrass and/or perennial ryegrass. (Cornell University)

Perennial ryegrass will not fill into bare spots or damaged areas because of its bunch type growth habit. It does not form thatch due to its lack of rhizomes. Perennial ryegrass is slightly more shade tolerant than Kentucky bluegrass, but may thin out in shaded areas overtime due to its lack of storage organs. Perennial ryegrass is very wear tolerant. (University of Idaho Extension)

Kentucky bluegrass does very well in sunny areas, it is very cold tolerant and will form a dense high quality turf when grown in full sunlight. A limiting factor to bluegrass is its lack of shade tolerance. Under heavy tree shade or on the north side of houses, it will thin and develop a powdery mildew. (University of Idaho Extension) Bluegrass is only a medium-good on wear tolerance, but not as durable as ryegrass.

Bluegrass is often incorporated with other grass species to produce a better multi-purpose lawn. A mixed blend can result in improved lawn appearance, earlier green-up, better fall color with better disease and insect resistance. Additions of fescue and perennial ryegrass are included in bluegrass for several reasons. Fescue tolerates shady areas where bluegrass may not get enough sunshine. Ryegrass is often mixed with bluegrass to achieve green-up earlier and its durability. Ryegrass is added to develop a tougher sod that stands up to tougher wear and tear. (Seed land)

 SEED LABELS

By, law seed labels list the % of grass type by weight. This, of course, is very confusing because not all seeds are the same size. For instance, bluegrass has 1,500,000 seed per pound while perennial rye has only 250,000 per pound. Even different bluegrasses have different seed counts per pound. So, it takes some figuring (example below), to figure out what % of each grass is actually there. This is called % of grass by seed count and is what really grows.

Example: Seed for Ideal Sod

By seed count:

Blue =60.88% of 50# = 30.04# x 1,500,000 seed/lb= 45,660,000

PRye =31.18% of 50# = 15.59# x 250,000 seed/lb= 3,897,500

Fescue= 6.63% of 50# = 3.32# x 382,000 seed/lb= 1,266,330

Total Seed= 50,823,830

Blue 45,660,000÷50,823,830=90.0%

PRye 3,897,500÷50,823,830= 7.5%

Fescue 1,266,330÷50,823,830= 2.5%

Now that’s said, there is one basic fact. Because money is involved, seed labels are forged and just because someone is waving a seed label around does not necessarily mean that is what got planted. So, you still have to do your homework on the performance and reputation of your supplier.