1. When do I cut the grasses back, and how far?
usually early spring....down to 6 inches most kinds, but i don't whack stipas or fescues. i don't whack carex. i do whack miscanthus, pennisetum, calmagrotsis.
2. Do all ornamentals get cut back or just certain ones?
certain ones.
3. Can I divide the grasses, or do I need to harvest seed?
dividing is best to increase your number of plants unless you are a very young man.
4. Some of the blues, not all, go partially yellow in the height of summer. Is this a lack of water or expected?
i have fescues and helictotrichon in the blue category. nope, they stay blue for me. they don't get much water neither.
get yourself to the local library and get an ornamental grass book. check it out. there are many informative books now on the subject.

LOL gives good advice. Nancy Ondra & Richard Darke have both written very good books on grasses, just to name two.

Doh! The library. Why didn't I think of that, it's my ususal stop. Thanks for the info. Ondra and Darke books are on the way.

There are both evergreen and deciduous (herbaceous) grasses - typically the deciduous ones get cut back in late winter or early spring and the evergreen ones do not. Deciduous grasses - in general - grow taller than evergreens and produce very showy seedheads. They also turn straw-colored in late fall and winter. Evergreen grasses tend to hold their color year round. Bronze colored grasses are most often of the genus Carex and are considered evergreen (or everbronze). Also most of the blues will be evergreen as well - the fescues, helichtotricon, elymus, etc. These only need occasional grooming to remove old fronds.

Most grasses propagate easily from division which is typically done in spring. Some will self seed easily as well - like the bronze carex. Many named cultivars produce few or sterile seeds so harvesting may be futile.

Blue coloring can vary from species to species and cultivar to cultivar - some will hold color better than others. In a hot, dry summer climate it is pretty common to have fescues and oat grass fade in their color intensity.

btw, the Darke book is essential if you have an interest in growing OG's.

Rick, try the link below. It will help you with how to cut back your grasses in the spring.

Blackie

Here is a link that might be useful: Spring cleanup

Greetings,
Can I cut them back after first frost here in Michigan?

Tnx

Well.......that depends, as a very wise gardening mentor used to answer in response to most gardening questions :-)) Depends on the OG in question and its hardiness. If deciduous and fully hardy in your zone, it won't hurt, but you will be losing a great deal of winter interest. In general, it is recommended to wait until new growth begins in spring.

BTW, it is considered proper GW etiquette to pose new questions in the form of a new thread, rather than piggybacking onto an old thread, specially when the OP requests email follow-ups. They don't necessarily want to receive a lot of irrelevent emails.......