FirstNations lays it all out in an easily understood format

Because I have been given a budget, I have been reduced to lurking around grocery and big box stores waiting for plants to go on clearance, and having made myself familiar with their items in stock I have to say that Lowes has the best quality for the best price.  In fact I am super duper damn impressed with their stock...I have yet to get a plugbound, rootbound or hacked-at plant, and so far never even a hint of fungus gnats, which is almost unheard-of when dealing with wholesale nursery stock.  The only thing they could improve, in fact, is to change suppliers when it comes to clematis...the poor things have been fed so much growth limiter they look like toy-breed vines.  Perfectly formed, just hit with the shrink ray.  It takes a lot of watering and plant food to wash that shit out of their systems.  So buy  your clematis at a regular nursery, but load up the car at Lowes.

The worst plants, of course, are at K-Mart.  If you know what you're doing you can pick up stuff and try to bring it back, but on the main give K-Mart a skip.  Sure, they carry some major name stock, but everything is tended by your typical K-Mart employee, with the inevitable result.

Around here the supermarkets are supplied in large part by Joes' Garden (go Joe!).  What starts out as premium locally grown material half the time falls victim to employee cluelessness, but since they started out healthy you can bring them back pretty successfully.  You will get potbound items since Joe's is chronically understaffed by college vegetarians with white people dreds working their first retail gig and not quite getting the concept of 'volume means speed'.  But I've already given you the instructions to deal with plug and potbound plants, so no worries.  Oh look it up.

Home Depot is fungus gnat central - -plus, they're out to scam you.  They always seem to accidentally on purpose choose plants suited for a USDA zone warmer than where the store's located.  The one here carries things like Confederate Jasmine, Mandevilla and Oleander for heaven's sake (we're USDA 7a.  Seriously, Lowes?  Total dick move.)  I guess they figure there's one born every minute or something and they'll get return customers wanting to replace the stuff that died.  Know your USDA zone before you shop there, and expect to do a little root salad surgery too.  Still, they do clearance things at the drop of a hat, and at an outrageous markdown simply for being past blossom time, which is all good.

Wal-Mart has a seasonal garden section, and if you don't mind feeling dirty and cheap afterward you could do worse than shop it.  They have shit for selection on ornamentals but their vegetable selection is pretty impressive.  Wal-Mart is usually where you'll find plugbound plants, unfortunately, so wait till they're clearanced and then go to town.  No sense in paying retail for something that isn't worth it from the getgo.

I've had good luck with the Proven Winners line.  Now you can get all peevish and say things about GMO and chemical fertilizers but when you've got a serious Jones like I do all that matters is putting that needle in your arm and Proven Winners tend to be damn good plants.

Monrovia is hit or miss - it isn't premium, that's for sure.  Their stock is held until the last damn dog is hung, the plants are hacked at and the roots are usually crawling out the bottom of the pots.  Time of the season doesn't seem to matter either.  The best thing to do is to go visit Oregon, which seems to be owned largely by the Japanese and Monrovia, and visit the Monrovia offices and talk to the staff and poke around in Monrovias' commercial fields and get run off and have trespassing charges pressed and possibly get eaten by Dobermans because they take their security SERIOUSLY.  Their holding yard outside of Mt. Angel looks like Stalag 13 for cripes sakes, and I mean chain link fences with fucking coils of razor wire on top.

Novalis is pretty meh.  Their stuff arrives unnaturally large and green and drug addicted and then languishes slowly for lack of the hypernutrients they're accustomed to.  Get them early in the year and then hold them for awhile, and plant in the evening because these plants shock out pretty dramatically.

Terra Novas seem pretty premium.  Never had a problem.  The plants aren't too drug addicted, although they've been fed MarketReady for sure, which is standard practice.

Bonnie, pretty average.  Nothing special but not substandard either.

Those are all the national brands I can think of. Now you know what I know.  The main thing to remember here is DON'T BELIEVE THE PLANTING INSTRUCTIONS.  When you buy a perennial nowadays, take it for granted that you will have to:

1. INSPECT THE ROOTBALL, which means tearing into it a little.  This does not kill the plant as long as you're careful.  If you trim away a certain amount on the rootball, take off an equal amount of the top growth to avoid serious plant shock.

2. Remove the flowers before planting, and plant in the evening, both of which also serve to keep the plant from shocking too badly.

3. Know your USDA zone and soil type.  Yes, you HAVE TO.

4. Have an idea beforehand about your property's sun exposure and the water needs of the soil so you don't do stupid shit like plant an echinacea in deep shade under an evergreen tree, which I have done.

5. Buy some neem oil based fungicide/insecticide soap and have it ready.  The stuff works pretty slick for an environmentally sound alternative, which is more than can be said for home remedies like olive oil, garlic and hot pepper, which bugs in general laugh at and fungus regards as delicious Italian food.

6. Call the county Extension if  you need answers. IT IS FREE. The Extension is a really under-utilized resource out there that you've been paying the government for; use the thing!  They have seriously nerdy nerds waiting for you to give them something to do besides look for interesting dead bugs in the window tracks and find flaws in the Linnaean system. 

You've sat in front of the computer long enough.  Now go forth and plant!