People take advantage of this all the time to control invasive plants in restoration sites. They apply during the months that natives are dormant and the target plants are still green. It tends to work well, as long as the non-targets do not have exposed green leaves, stems, or crowns. Just remember that the action of the herbicide will be very slow.

Jayk,
How slow?
I did a RoundUp attack on japanese honeysuckle and garlic mustard about two weeks ago and haven't seen much change yet (maybe a little here and there, hard to say). Should it have shown some sign of effect by now?

Bob, did you use regular Roundup (which has Glyphosate) or the Roundup® Poison Ivy & Tough Brush Killer? For jap. honeysuckle you want to use the brush killer one (which has some Triclopyr in addition to Glyphosate).

Here is a link that might be useful: Interesting article by the way

I used regular RoundUp (just glyophosphate and surfactant). I will look into the brush killer. Thanks.

I sprayed lots of Garlic Mustard last winter and early spring, and it took a couple of weeks to really show much change. I think everything I sprayed (with regular Roundup) eventually died, but not much change was apparent at first, especially during cold weather. Once the weather warmed up the plants died. i only sprayed on warmer days when air temperature was about 50 degrees or so.

I don't believe RU will work now in zone 5. Below is from their website

When to Apply

Apply when weeds are actively growing. For best results, apply during warm, sunny weather (above 60° F).

Thanks for the info. I'll try to target the culprits on a warm sunny day. It's certainly worth a try!

Some winter weeds and grasses ARE actively growing during winter. Obvious examples include winter rye, Garlic Mustard, and dandelions. I still think it is important to wait for a warm day to make sure the plants are at least trying to photosynthesize and move nutrients from roots to leaves and vise versa, but I think you can try to spray this time of year. You can't wait too long or you risk hurting the plants you want to save.

I have used ordinary roundup to spray japanese honeysuckle into late fall, especially when we've had warm weather and the vines are still very green. The results were not evident for a long time, but there was little honeysuckle present the following growing season.

A lot of the leaves of the japanese honeysuckle that I sprayed appear to have turned from green to a sort of purple. Maybe the spraying worked after all.

Sorry bob, but that is the usual fall coloration for japanese honeysuckle. I don't think you can use that as a sign.

Oh Well.

Would Roundup application work well on bermuda grass? I have a patch of lawn out front that I would LOVE to get rid of. Hate bermuda grass. I also have a dormant hibiscus moscheutos, and buddleia nanho - that is all - in the ground. I would like to attack this problem while I can, before new growth starts in spring.

Would it need several applications spaced 2 weeks apart? I hate, hate, hate using chemicals, but I am willing to do anything to get rid of the bermuda so I can plant natives in this space. I am slowly converting to natives for a butterfly and moth garden. This is my only space with day-long full sun and I really need it.

Right now we have icy-packed sleet on the ground, so no, I wouldn't be doing anything until probably February.

Susan

susanlynne - yes Roundup or any other non-selective herbicide will kill Bermuda grass, but the grass needs to be actively growing first. You'll have to wait until it greens up in the spring/early summer. Unforunately that is when your other plants will have growth on them, so you'll have to take care to avoid any overspray drifting onto those plants.

Bermuda grass is very tough to kill, so I suspect it will take several applications.

Is digging it up an option? Depending on the size of the space, you could hire someone to do that. That would be the quickest solution.

Thanks, Esh! No, I think I will go ahead with my lasagna garden plant. It's not that large a space (about 10x30', or 300 sf). I can just lay down the newspapers and hold them in place with bricks or stone, and have my soil (top and compost) delivered and dumped on top, as well as some mulch.

I think that is the better plan, and w/o using chemicals.