Hi Linda,

Preen can not be worked into the soil, it is a preventative herbicide that works by forming a layer on top of the soil that prohibits germination of seeds. The minute you break the surface of the soil that layer is destroyed and it is no longer effective.

Round up is tough in this area because you have to keep applying and applying, kind of like pulling and pulling.

I have about the same kind of problem keeping my prairie in the prairie. I use a heavy black edging between the prairie and the garden and then mulch heavily. It at least helps you to notice when the weeds are invading. Not a perfect solution...if one shows up here in this forum, I am listening.

Good luck, Helen.

As Helen said, Preen won't kill weeds, it keeps new ones from germinating. It will have no effect on perennial weeds that are already established. Your best bet is probably to use a combination of controls, barrier/edging, mulch, Preen, Round-up. When I've needed to apply Round-up in difficult areas, I've sometimes used a brush to "paint" it on the plants I want to eradicate. Good luck!

It's a dilema isn't it? Round-up only kills the emerged weeds and I find it doesn't always get down and kill the roots like it's supposed to. The Preen only prevents the seeds from germinating and does nothing for the rhizome type spreaders.
Layers of wet newspaper topped with mulch are the only thing that I can recommend short of double-digging and bringing in weed free soil..and I am battling the same problems with my old converted cow pasture and it's lovable cockleburrs and quackgrass. Stay strong and persevere!

The never ending WEED!!

Round up in fall also..nettles and poison ivy.
weed whip your nettles befor the seed gets mature.
Preen is for on top of the ground, It has some kind of oil in it that helps spread the chemical on top of the dirt to prevent new weeds.
I like the newspaper and mulch deal,time consuming but so is weeding, but you can never stop new seeds from producing and mature plants and trees..