"Any ideas on how this happened?"

Yea, It looks like you did what I did to my rose garden this past winter spring.

I strongly suspect seed heads from the lawn were mowed and dumped in the compost pile. The pile did not heat up enough or uniformly to kill the seeds. The compost/mulch was spread and ,"BAM", a nice grass seeded flower bed, or rose bed in my case.

This past month I broke down and sprayed two applications of roundup over a three week period. (Luckily they are well established roses so that even though I was careful the bit of overspray was not damaging to them. In your case it might not be as easy to protect the plants you want.) Then I put down several layers of paper and then about 4-6" of shredded bark mulch.

atomicdad!!!! Where you been at? You haven't been posting as much lately and I miss your comments.
Thanks for the response; so in other words I'm screwed. Man! My plan and hope is that once I get the bed weeded I'll put down a heavy mulch - NOT grass clippings - and then any weeds that manage to get through will be easier to pull. Well one thing is for sure, I will never, I say NEVER start a garden this way again(said with Scarlet O'hara acccent)!!! From now on it's going to mulch over the compost, and the plants I put in will either be free, store bought, or seeds started indoors.
Put this down in the Worst Gardening Mistakes EVER book.
Thanks atomicdad for the insight and commiseration, it's nice to know I'm not the only dumb**s out there. I say that with the utmost affection and respect. :) Seriously, don't take that the wrong way. :)
Jennifer

Anytime I've made a new bed I've had an invasion of crabgrass. Before I knew about compost I had a crabgrass invasion. I think the seeds stay viable for a long time in the soil just waiting for the opportunity. The last beds I made were all compost or compost, peat and sand (see concrete block pics) and no crabgrass invasion at all. I doubt that I maintain a hot enough pile and I have clippings from the neighborhood lawn guy thrown in.

Sorry you had such a mess, it's a lot of work. Next spring you'll be showing pictures of your beautiful bed you built last year.

Thanks for the encouragement Kathy. I hope that I can show pictures of a garden as lovely as yours!
Jennifer
ps
are all those children yours?
:)

Oh how depressing! I hope it gets better!

Jennifer, I've been checking in, just not posting as much. No offense taken about being a dumb@$$, some people think that is my middle name ; ), actually, that is what my wife said when I told her how I suspected our rose bed got so bad this year. I'll try to get a pic posted of how it looks now with the bark mulch up this weekend.

Dan

Oh yes yardkat, very depressing, but then that's why I came to you guys with it. This place is like group therapy for troubled gardeners! I'm very excited for you and your backyard project, can't wait to see some pics!

Speaking of pics, that would be great Dan! Glad you were cool with the dumb@$$ thing.
:)
Jennifer

Ouch ouch ouch Jennifer. Too much fun. I have to agree that the crabgrass may have been present in the soil already and the only mistake you made was stirring it to the top. Without knowing of course. Doodoo occurs. You can handpick, or start over with a cultivator and strip everything off. Since you know the hazard now, mulching heavily would be a good prescriptive practice to keep it at bay. Mother Nature hates bare earth. She will cover it very quickly if you don't.

Hey Bill,
Thanks for the tea and sympathy! What kind of cultivator would you use for a project like this? I hope to get a truck load of wood chips soon to mulch with, you're right I will never make this mistake again....I'm sure I'll make all new ones to tell you about!
Thanks
Jennifer

Something like this.

{{gwi:257088}}

It's good for scratching mulch and dirt, and good for mixing compost. Pretty handy and fairly cheap.

Neat tool! Looks kind of like a bent pitch fork. I'll look for it the next time I'm at the hardware store (I love hardware stores don't you? Somethin' about all those tools just waiting to be used for yet unimagined projects).
Jennifer

Jennifer, no they are not all mine :), the only pictures I had of the backyard were from my son's b-day party. Since I've had my digital camera almost all of the pictures are my yard and very few of my son. I told him I would put him next to every plant I take a picture of so I could alleve the guilt and still get some garden shots!

NO TIME TO READ ALL THE OTHER REPLIES SO HERE GOES WHEN YOU ROTOTILL THE TINY CRAB GRASS THAT YOU HAVE SEEDS COME TO SURFACE YOU ACTIVATED THEM NOW THEY ARE THERE FOR AWHILE TILL YOU RID THEM OUT THEY WILL GO AWAY WITH A GOOD FROST.

Well thats too bad that you got crabgrass and not a lovely flowerbed... I would get a mini rototiller and just keep rototilling it onces a month or so...That way you keep mixing in the old compost and break down the new compost as you mix it in..
Then comes spring you should have a nice composted bed ready for your new flowers...
Good luck...

just get a "Garden Weasel,or that tool with 4 tines,that you stab in the ground and twist(I can't think of the name of it,but you'll know it when you see it),.Get the Hound Dog brand,they are great and a lot cheaper.And not all that much more work.
After the first few passes thru the dirt it gets really easy to use.
And all I had in my yard last spring was ORANGE clay.
dirt moves easy now.

DONT CRY , COVER THE BEDS WITH BLACK PLASTIC,CARDBOARD, OR ANTHING TO BLOCK OUT THE SUN AND MOTHER NATURE WILL KILL ANYTHING NOT WANTED. THIS WILL ALSO INCREASE THE MICROHERDS IN THE BED AND MAKE THE BEST PLANTING SOIL AVAILABLE.. BILL

Don't feel bad! I get tons of that s#$t from my neighbors yards! They don't try at all to control crap grass or clover (they have lovley white carpeted lawns most of the summer then the cg takes over) Its a royal battle trying to keep it out of my yard. The cg seed heads ripen, then when they break off, blower all over, spreading their wonderful presents. I've built a raised bed (3') along one lot line to keep their mess from filtering into my yard, and that's helping.

It could be worse - think mugwort, or canadian thistle, or bindweed. But my sympathies anyway. Hopefully it's all under control 3 1/2 years later... :-)

If it was bermuda grass she is probably still battling it. (doesn't look like bermuda in the pic though)

Bill_G?? Bill_G is over here?? Hey, Bill_G, how are you?
And Garden Nymph!
Been missing you two!

Ah, Marty, they posted years ago. :(