What to do with hillside invasive plants?

[Anonymous]

OP here. Thanks for the ideas.

The size of the hill is actually quite large. It would be cost prohibitive to densely plant, but perhaps I could make that part of the end goal. It's a shady hill, lots of tall trees around. Deer come by our area regularly, though now that my yard is pretty bare they haven't been around much. Evergreen shrubs sound nice.

I've been googling the mystery plant and I don't think it is Japanese knotwood. I actually think it may be two separate mystery plants. I dug out massive roots of it recently, but I will take some pictures and submit to a gardening expert to see what I'm dealing with when it grows back. I have some small growth now that I can submit.

I hadn't thought about tarps or even heard about flaming weeds! I need to do a little more research on tarps, landscape fabric, and maybe even RoundUp. Although I'd rather avoid chemicals, I think the majority of the hills is invasive stuff that needs to go before it invades all my neighbors too. Some of these weeds grow to be huge so I don't even know if landscape fabric could keep them back. I also wonder if maybe RoundUp will not work on the mystery plant because I already dug out huge clumps so there isn't much above ground at present. I have a lot to consider with this massive project, but again I appreciate all the ideas.



Also to the NP in similar situation, we hired a guy who comes around our neighborhood sometimes and asks to cut grass. He has done a few side yard projects for us, but he's not a service or anything. I think most landscaping services could quote you on hand pulling weeds. On the bamboo, we thankfully did not have a huge problem. I was able to dig it all up because it had only started encroaching. I put in a barrier last fall and this spring only a handful of new shoots came up, all along the same rhizome. I was able to simply dig up that rhizome. Now if only I could do the same with these other crazy things! By the way, we used this barrier: https://www.amazon.com/gp/product/B00UB4YYNO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

[Anonymous]

OP please report back on the mystery plant!

We have a lot of invasives in our backyard too although not to that extent thankfully!

[Anonymous]

Update - - one plant was identified as American pokeweed: https://www.marylandbiodiversity.com/view/1590

I can't identify the other because I dug it all up before taking a picture and I don't have pictures from last year so I will wait for it to grow back. It doesn't seem like the pokeweed grows on rhizome, so I think I have another big weed I'm dealing with. I also sent a smaller weed picture to them and can report back on that too.

The pokeweed confuses me because it is said to be native and important for birds, but also invasive and poisonous. We have toddlers so I think it has to go, since even eating one or two berries could kill them!

I have pulled enormous taproots up, one was like a foot in diameter. I am not sure if the giant root stumps I dug up were from the pokeweed or the second big mystery plant, but either way I have tons of pokeweed. I may have done OK by digging up the little pokeweeds this spring already. I probably dug up 150 of them ranging from 2 inches to 2 feet... but on many the roots broke before I got to the bottom. I read that because of their strong root system I may need to use chemicals to control them and just be vigilant against the new growth.

[Anonymous]

Depending on the slope and how big of an erosion problem you might have, you could consider covering the whole slope in landscape fabric and leaving it until next Spring. It should solarize/smother any remaining roots and give them time to die. It obviously wouldn't look great but this is how I converted my lawn to flower beds, and I just covered the landscape fabric with mulch for the first summer/fall and it was adequately presentable.

IMO the key is, you pull up the landscape fabric at the end of the initial period. Long term it will just be a mess and weeds will grow on top of it. But for the initial smothering, it was great. I also used cardboard which was also effective but it broke down pretty quickly and I'm not sure everything was completely killed. After I pulled up the landscape fabric I used a big fork to dig in a bunch of compost before planting. So far (a few years) I haven't had any noticeable issues with grass or old perennial weeds from the lawn coming back. I have weeds obviously, but mostly annuals.

As I mentioned, people also do this with cardboard and tarps and such. But my preferred method would be the landscape fabric. It is kind of wasteful, but I reuse a lot of the fabric each year for vegetables.

One important caveat - The fabric that I used, where it wasn't covered with mulch, rotted from the sun and was a PITA to remove. So make sure you know it's sun-proof if you're not going to cover it. I think that would mean using the thicker, shinier kind and not the dull matte stuff from Home Depot. I think Floret Blog has a bunch of info on landscape fabric and theirs is sunproof.

[Anonymous]

I have been looking into the tarps, fabric, flame, and chemical suggestions. I think flame is not going to work as burning poison ivy is not good. I might end up doing a mixture of approaches, I know it will take time. Thanks for the thoughts on the pros/cons of covering with mulch. My inclination is to try one of these to smother the current situation (got them from searching from the Floret Blog). I could leave them up all summer. Since it's pretty hidden in the backyard, I'm OK with it looking ugly...

1. https://www.target.com/p/dewitt-sunbelt-6-wide-woven-weed-barrier-landscape-fabric-ground-cover-300/-/A-76020920

2. https://www.target.com/p/dewitt-p6-pro-5-commercial-landscape-5-ounce-weed-barrier-fabric-6-x-250-feet/-/A-76116011

[Anonymous]

When we needed to kill a large area of poison ivy we covered it with black plastic. Not landscape fabric. My husband got a big roll at Home Depot for less than the landscape fabric. This will let thru no water and the sun on the black plastic will heat up and kill things quickly. I think we left it on for 2 months and then spent a day (hire someone) to go in and pull the roots out. We started the process mid spring and had new plants in the ground in Sept. Yes it look bad for the summer but we never had poison ivy in that location 15 years running now.

[Anonymous]

Fern that spread by runner. They will fill the area in a few seasons.

[Anonymous]

I've been dealing with similar issues since I bought our current house five years ago, so I feel your pain! My topline thought -- this is a marathon, not a sprint. You're likely going to have to take a longer view because you're not going to solve this overnight.

Pokeweed is not invasive by definition, it's just aggressive -- it does have a lot of wildlife value, and if you have kids old enough to know not to eat strange berries, it's not hugely dangerous. (I assume your toddlers won't be foraging on their own back there!). That said, it is quite aggressive and the roots on those things are insane as you've found, so there's nothing wrong with getting rid of it/staying on top of it. Just know that you will likely keep getting new plants because the birds love the berries and will plant them for you. Unfortunately, same with poison ivy, also a native with great wildlife value so the birds love (and spread) the berries.

Is there a budget to hire professionals to do the removal? Large areas of poison ivy really are no joke -- you basically need to wear Tyvek suits. And 100% you cannot and should not try to flame weed poison ivy.

In terms of plants to replace, I agree with the PP who say don't use a landscape fabric that stays in place or you will likely live to regret it. It's different if you solarize a large area on the understanding that you will remove the solarizing material, but then you really do have to get on top of planting and mulching on a large scale or you will be back where you began.

You can try using large areas of cardboard (with all tape/plastic removed) covered by a very thick layer of heavy wood chips. This is the kind of quantity that you'd want delivered in a dumptruck in bulk, not in bags. You can work around plants that you plant to replace/stabilize the slope and as the cardboard and wood chips break down, you can plant more plants and the ones you have will spread.

In terms of great native plants that are aggressive and like part-shade/shade and dry to dryish soil, here are some ideas for plants that self-seed, spread by runner, or otherwise will happily multiply on their own:

Packera aurea (golden groundsel) spreads like crazy
Eurybia divaricata (white wood aster)
Tiarella cordifolia (foamflower)
Heuchera spp. (alumroot)
Ferns like ostrich fern, sensitive fern, Christmas fern. Ostrich fern in particular multiplies like crazy and is super easy to transplant.
Aquilegia canadensis (columbine)
Carex spp. (sedges -- esp. Pennsylvia)
Polemonium reptans (Jacob's ladder)

This all does not have to break the bank because you do not need to buy giant plants -- you could buy plugs or small plants and just wait for them to spread on their own. My favorite source of native plants in flats of plugs or deep plugs is izelplants.com, which has a great set of filters so you can drill down to plants native to where you live as well as the conditions they like, deer resistance, bird/pollinator attractiveness, etc.

These are super long and I haven't watched them yet but they look really helpful:

https://www.youtube.com/watch?v=I412efrY0Zs

(although your'e dealing with aggressive natives, not non-native invasives )

https://www.youtube.com/watch?v=1vGtxqY3v_E

[Anonymous]

Thanks to all for these tips! You helped me come up with a plan where I had none And the plan is quite affordable to start, then I can see how it goes and adjust.

For the lower hill that is more manageable and has a few ferns, etc. I am going to try the cardboard and mulch idea. For the upper part of the hill that has all the poison ivy, pokeweed, garlic mustard roots, etc. I am going to try the black tarps. I am going to put it down after the ground get wet in the upcoming week. I think we will need to keep ours up a while because it's shady and the roots are just so massive. I'll see how it goes and then see how it looks!