Growing wildflowers - where do all the weeds come from???

This year I opened up a long strip of land (about 100 ft. long by 2 feet deep) in my back yard in front of the wetlands, with the intent to grow some annual wildflowers. Here is the history what I did and when:

- last summer I used my mower to mow close to the ground to cut the wetlands down to ground level ( to extend our yard back a bit)
- i tilled the new open area, and we brought in more dirt to level out the back yard in front of the wetlands
- we put landscape fabric and mulch over the new dirt (between the wetlands and our established yard)

- this spring I decided I wanted to TRY to grow wildflowers just in front of the wetlands, so I pulled up and cut out the landscape fabric (about 2 feet deep), and tried to rake out the weeds,
- I tilled the dirt along this long strip in front of the wetlands
- I added about 2 inches of a mixture of top soil and peat moss, and tried to rake or hand pull out all the weeds
- In early May, I planted various packets of wildflower seeds, sunflower seeds, zinnias, cosmos, allyssum...
- I watered some days, but not everyday as I should have (as it was a dry spring), so i think i lost a lot of my planted seeds

Result:
My sunflowers are doing great! I also got lots of cosmos, allyssum, some zinneas, lots of milkweed (i left many of these to attract monarchs), a few other wildflowers that i don't know the names, but mostly LOTS OF WEEDS!

OK, now I admit that this was an experiment and I didn't keep up with the watering as i should have (as my perennial beds and roses keep me busy, too), but my question is where do all those dog-gone weeds come from??? After some helpful weed identifications on this site from you all, I have pulled lots of pigweed, thistle, velvetleaf, ragweed, and other weeds. I'm just so surprised at all these weeds, as most of them don't even appear to be in the wetlands that are behind this new open dirt area.

Please let me know what I could do so that I can have better luck at this next year. I'm not sure that I want to do this again, since I unfortunately got more weeds than good wildflowers. I may have to just divide some of my "wilder" perennials (purple coneflowers, black-eyed susans, daisies, bee balm, ..) and move them back there and surround with mulch, as this may be an easier to maintain than attempting wildflower seeds on open dirt again. Do you have any ideas for me?

weed seed can come from almost anywhere: blowing around on a breeze, bird droppings, even laying dormant in the soil.. until the right opportunity comes along to sprout.

you created the perfect setting for weeds really...lol. you got rid of it's competitors (grasses) tilled up the ground and made it nice and welcome for sprouting, then planted flower seeds to give is a great camouflage to grow in. not to mention, if you bought wildflower seed in bulk, chances are there were some weed seed mixed in as well.. they can never truly eliminate weed from mixes completely, so they limit it to a standard of 'acceptable' amounts of weed seed in any given mix.

this happened to me when I cleared an area of lawn for a flower bed... no sign of weed really when i ripped out the grass, but ever since the flower bed has been in, I've pulled at least five different kinds of weeds outta that garden on a daily basis.

its always an uphill battle with weeds, but if ya look at it like my grandmother did then, 'There is no such thing as a weed, it is only a wildflower out of place... and every flower has it's place".

Do you want to use chemical's?? If so, spray the hell out of it with ROUND-UP, wait two week's, till it up and plant what you want. It work's, have started several lawn's this way.

round-up does not prevent new weeds from moving in though. as cue said, you have created a perfect environment.

i would spray and start over but with one small addition, mulch-mulch-mulch. then move pieces and plant your seeds.

i have my main garden bed completely mulched but recently dug out many old plants and added new ones. just by disturbing the soil, the weeds had the opportunity to get a foothold. i have to re-mulch those areas now.

Agreeing, tilling sets up a perfect site. I've stopped tilling unless I absolutely have to, then cover with black plastic for a couple of weeks to sprout/kill any weed seeds that are turned up. Take up the plastic, rake out anything that has grown/died. Now spread your seed.

You will still have some weeding, but not from seed that was dormant.

Thanks....you are all so helpful in your advice. I will take a different approach next year, and this year I will keep pulling those weeds, and add mulch to keep new seeds away, and enjoy the wildflowers that did make it! Thanks!