@mishmosh

Thank you, you clearly know what you're talking about so I really appreciate your help.

You don't share the reservations about Outside Pride that I've seen?

What do you think you would do, optimally, in my situation? Seasonal flooding, drought in the summer, dappled shade--I'm assuming that you're in/familiar with the area west of the Cascades, given everything.

What about using some shade-optimized tall fescue (for the clay) or bentgrass (hardy, shade) too? Don't know if you're in Oregon, but PT Lawn has a biofilter turf mix for the shade that looks good (annual ryegrass, poa trivialis, creeping red fescue, creeping/colonial bentgrasses). Any opinion on that?

BTW: I am not concerned about color at all, wish I had the luxury of that. Just want something to grow and STAY over the winter. Have you tried poa supina at all? It looks better than trivialis in a lot of ways, most importantly wear quality/durability over the long term. And if you add 10% to a mix of other grasses, it apparently ultimately takes over, which is cool. Check out, e.g., MSU (they are playing football on it, this is no fine fescue!).

Oregon grows more cool season turf grass seed than anywhere else in the country. You should have no difficulty at all in locating a heavy duty shade blend mix formulated specifically for your area.

However, regardless of what sort of grass seed you use, unless you can correct the existing conditions - compaction, assumed low fertility, drainage issues, shade - you are never going to develop a thick, healthy lawn. The odds are stacked against you.

For a rental property, I'm not sure I would spend the $$, the time or the effort. And we have passed the window for spring seeding in the PNW....it will be tough to get any new seed established now before the summer heat and drought set in.

Thanks, gardengal! Yep, if it was my property, I'd definitely do a groundcover/permeable hardscaping. But I'm not going to sit around in dirt all summer. It's not that late; that's just the reason that I posed the question whether to even bother with anything other than just putting down ryegrass. Grass seed isn't terribly expensive, you know?

While we do grow a ton of grass seed, it is surprisingly difficult to find a turfgrass that works in this situation here. Literally, the only place that I've found poa supina available for retail mail order to Oregon is Outside Pride. And apparently, poa trivialis is being phased out for use overseeding on southern golf courts as an institutional practice, so supplies of it are very hard to find.

But that's because, as you say--this really isn't meant to have lawn w/o some major investment in the soil. But I'm between a rock and a hard place as a broke renter: it's lawn seed and then maybe think about some hardy ornamentals suited to clay and shade to start from bare roots when they're cheap, in the fall.

I've not had issues with Outside Pride or their seed products. Their seed is not certified but I don't think that's a problem in this instance. If your problem is very wet soil spring and fall coupled with shade, poa trivialis is a good choice. it is extremely cold tolerant. Once established, it goes dormant in the summer if not irrigated but survives just fine. If you plant it now, you will have to irrigate through the summer to keep it alive--but that's probably true no matter what you plant if you do it now.

I have no experience with Supina.

If a spot is really shady it is just not possible to have a nice thick lawn, no matter what kind of grass is planted. And if the involved soil is greasy when wet, kept moist with irrigation all summer then trying to walk on it repeatedly - such as when mowing, for instance - can be problematic.