Have you tried a chemical approach such as Round Up? The only other advice is to dig them up with a trowel, making sure to get the bulb.

- Brent

I thought this subject line referred to the fact that this avocation (vocation, in some instances) of ours can easily "clear the bank" of one's assets.

How large of an area are we talking about? If it's not too large you could rototill the entire area, wait a couple of days and till again, then lay down a good layer of compost and plant.

I've had success with the wet layers of newspaper covered with compost as well, in a smaller area.

Patty

Concentrated Roundup applied at nearly full strength to bruised foliage (it's waxy on the outside, and resists the chemical) is reported to work. So are 2,4D based products, but they're fairly toxic, so you might want to avoid them.

I wonder if you could try solarization? This involves watering the area to moisten the soil, then covering it with clear plastic and letting the sun cook the weeds to death. It also kills insects and soil pathogens, but may take 4-6 weeks during the hottest part of the summer. This would delay your planting plans until late summer, but might be worth a try.

I've also read that cutting them down repeatedly will eventually weaken and kill the bulb, especially if you start now, in the spring. Even if you get them all, you'll have to be vigilant, because if they're in your neighbor's yard, they'll return.

Also, don't let them go to seed!

"long bank" ...
"steep bank" ...
"thick wild onion plants"

This area will be in almost full sun and likely has only a thin cover of topsoil over a compacted subsoil rich in clay.

Eradicating wild onion from this site will be a long and difficult process and will also kill everything on it. The result will be heavy erosion. I suggest you stop and consider what a bare eroded slope that won't grow anything will look like.

First you should determine the degree of slope you have. Then consider changing to only those things that can be done successfully on that steep of slope. It probably isn't flowers.

Work on this slope in phases. Do no more than a 5 foot strip accross the slope at any one time. Make sure the soil is stable and the ground cover is well istablished before starting the next strip.

Construction on a slope should start at the bottom and work up. But planting should start at the top and work down. The reason for this is that erosion starts at the bottom and goes up. If you start at the bottom and amend the soil for good plant growth you give erosion the foothold it needs. The erosion will follow you up the slope. Start at the top!

squeek,
You already know you have a major problem. There is no way that hand removal or smothering with layered newspaper will solve your problem. This is a situation that requires some strategy and an understanding that several necessary steps must be taken over several years for complete removal. You really should hire someone with a commercial spray license, able to use stronger chemicals completing a 'kill' in one application. Before I give you the DIY method....is there presently grass also growing on the slope?

No, there is no grass. Leaving them there is not an option, as we are appalled by the smell, the lack of color, and simply put...they are ugly. If I do the Round-up method, how long would it be before I can replant flowers there? The area is 20 foot long by 3 foot wide. It is in partial sun. Will wetting them down ease the digging process?

Again...strongly suggest hiring a professional to do the spraying. The DIY method is to purchase Image which is a selective weed killer. It is expensive but far more effective for this problem. Mix according to package instructions. Using a weedeater, weed-whack everything on the slope back one-half and immediately spray. Be patient as it will be a week or more before dying foliage is noted.

Doubtful that one treatment will give you a complete kill. This is a difficult problem weed. Best not to plant this year. You are anxious to grow flowers, but rushing ahead this year will find you facing the same problem in several years. Mulch the slope. Grit your teeth and live with the bare look this growing season, spraying any stragglers when you spot them. Be diligent for regrowth next spring as the weather warms. Stand some large planted pots in front of the slope to soften the look for this season. Time, tide and wild onions wait for no man!

I totally agree with nandina about being patient and doing it right. We had an area about 65'x 30' that was filled with blackberry vines and other hard to kill weeds and we wanted to plant a wildflower meadow there. We started last spring (2006) with spraying the round-up, clearing the dead stuff, and repeated it 3-4 times all summer until winter came. Then, we covered the entire area with black plastic over the winter. This spring, we took off the plastic and waited. There was a very small amount of weeds that appeared!!! We dug them out, lightly rotor tilled the area and planted the wildflower seeds. They are coming up now. There are a few other weeds and an occasional blackberry popping up and I go out there and hand-pull them up. Hopefully, the wildflower meadow will fill in over the next couple of years and crowd out anything else that is attempting to come up.

Take your time. When you are really trying to get rid of an invasive spreader, you need to be sure it's eradicated before you plant something else.

Good luck