Grassy weeds are out of control

We have a garden in our back yard, about 400 sqft or so, and in the center of it is a bathtub-sized pond. We love the pond, it is home to frogs and dragonflies and pollinators, which in turn attract birds, and the whole scene there is enchanting and lovely.

But some kind of grassy weed has taken over, first around the edges of the pond and now it’s colonized the whole garden. We can rip out as much of it as we like but it grows back seemingly overnight. Somehow it’s also taken over a raised bed in a totally different part of the property, so the pond might be incidental.

I think it might be nimblewill or crabgrass. Looking for suggestions on how to tame it without the use of either poisons or unreasonable amounts of labor.

Personally, I would remove it the best that I can and then drop creeping thyme and/or clover seeds in the area to try to offset the grass. You can watch them battle with each other, the grass may come out on top depending on what kind it is.

if you cover grass with a tarp or black plastic sheeting, it will die fairly quickly. Even used cardboard works pretty well. We have done weed control with old pizza boxes (which seem to accumulate at an alarming rate!). Of course the sun-block does not get rid of seed load, but then neither does a spraying of herbicide. Once the grass under the cover is dead and you remove the cover, new grass will sprout and you can then repeat the treatment. After seeds have germinated and been killed by cover, you are relatively safe to plant a chosen cover crop. Try to go native with your planting for optimal results: natives can thrive in the local climate without added watering and can support local insects which in turn support healthy soil and surrounding ecosystem.

To minimize use of plastic, you can do small areas of several square feet at a time. It takes longer, but allows many more uses of a single bit of plastic before you are inclined to discard it. Cardboard is generally only good for one reuse before it disintegrates.

Does it spread by its roots? If so, then a hungry goat would be best. I had clover spread like wildfire on one veggie patch and I just gave up and planted berry bushes there. Ripping all meandering roots would have taken me to an early grave.

Cardboard with 6 inches to 12 inches of wood chips or mulch will work well unless that grass spreads by roots as long as all the grass is covered so it cannot see sunlight.

Otherwise digging it out seems possible.

My thought is to try sowing parsnips very densely, especially the wild kind, and leave most of them in, until they make stalks. In mid summer of the year after next, when they are flowering, VERY carefully cut them down (gloves and long sleeves) and lay them as chop and drop mulch. (Or let them go to seed if you'd like.) Nancy Reading has done this with angelica too: the key is large, shady biennials, which are perfectly suited to invade low grassy habitats and initiate the transformation into a taller oldfield habitat, and eventually into forest.

Actually, now that I think of it, evening primrose could work too if you disturb the soil first. They are an earlier succession plant better for poorer, more disturbed soils. But they'd be less of a hazard!

Or... there is another plant I know. Jewelweed can also take back an area and shade out the grass completely, and is a non-hazardous annual. They do prefer part shade, but aren't as useful as parsnip.

I used my chickens to clear violets that were taking over my garden, however I couldn’t plant anything in there while they were working for obvious reasons. I heard ducks and geese eat grass and don’t disturb gardens. You could also use one of those large propane torches to kill the grass. I used one to stop thistle from spreading in my driveway by scorching the fluffy seeds before they could spread.

Is your grass growing flat to the ground or more upright?  If flat, it could be crab grass.  Crab grass is an annual, but the plant makes gazillions of seeds that are happy to germinate once the soil warms up.    If it is more upright, then possibly nimblewill which is a perennial grass.  Both plants are warm season grasses (meaning they grow like gangbusters after it gets warmer.
The smothering techniques with cardboard/mulch should work (probably better on the crabgrass since the nimblewill might creep out from underneath before it croaks).    A long term strategy is to make sure your natural area has more cool season sedges.  These will shade & cool the soil and take up space before the the opportunistic warm season grasses take over.  

I would imagine it's reed canarygrass? Crabgrass doesn't like wet soil very much, nimbewill might though. If it's still green it's definitely not crabgrass or nimbewill since it would have died with a frost. Reed canary is very aggressive, it's what you'll tend to see growing in thickets out of wet ditches or around ponds. It spreads by rhizomes and paradoxically is both very wet and drought adapted, probably because its roots are so deep.

Whatever the plant is, the way to deal with it is either starting from a clean slate by complete smothering or tillage, or incorporating it is a groundcover and establishing plants during its period of greatest weakness. For example if it's reed canary, you could mow it repeatedly throughout spring to weaken its root reserves, then once it starts to get hot transplant something that grows quickly and loves sun and heat. Sweet potatoes, tomatoes, corn, squash, sunflowers, etc.

If it's crabgrass it is an annual so simply mowing or pulling once it emerges in late spring to early summer should keep it at bay. Nimbewill is perennial but shouldn't spread so aggressively so I imagine that's not it.

Last week, I thought a lot about this topic in regards to content for my upcoming book. Here's a summary.

My Approach to Taming Weedy Grasses by natural means.

I’ve worked with smooth brome and other rhizomatous grasses for years. They can feel overwhelming, but I’ve learned that the easiest solutions tend to come from shifting the ecology, not attacking the grass itself.

Here are the main strategies that helped me turn dense grass patches into diverse, cooperative plant communities—without bought inputs and without back-breaking labor.

You don’t need to kill the grass. You just need to remove its advantage.

Rhizomatous grasses overpower gardens because they love:

full sun
bacterial-dominant soil
constant disturbance
thin litter
bare edges
early spring warmth

If we gently reverse those conditions, the grasses simply lose dominance and other plants step in.

Add logs on-contour (or just laying calmly on the soil)

This is the simplest game-changer I’ve ever found.

A single log creates:
shade at the soil line
fungal habitat
moisture retention
a small duff-catching terrace
a cool root zone that grasses dislike

A whole row of logs—especially under fruit or perennial plantings—acts as a fungal corridor. Grasses relax; forbs and shrubs move in.
You don’t need a pattern. Just place the wood where it feels stable.

Leaf piles as powerful allies

A thick pile of leaves (6–12 inches) in a grassy patch will:
smother the crowns a bit
keep the soil cool and moist
invite fungi
slow the spring green-up of the grass
make planting easier next year

This works even better near shade or fruit trees. If you’ve got autumn leaves—use them where the grass bugs you most.

Plant big-leaf, early-spring perennials

Grasses make their move early. If you plant species that shade the soil in April and May, the grass loses its first-mover advantage.

My favorites:
rhubarb (spectacular competitor once established)
asparagus (surprisingly grass-tolerant)
mullein
oriental poppies
asters
flax (Linum lewisii)
Anything that throws early shade helps.

Radishes and turnips punch right through turf

In cool seasons, I scatter handfuls of old radish or turnip seed.

They:
drill holes through sod
shade the soil
make planting pockets
shift the soil food web
distract flea beetles from tender crops
They’re cheap, fast, and easy.

If you’re dealing with a really aggressive patch: scalp a strip

Sometimes I scalp a 1–2 foot strip of sod and plant a parasite/companion guild:

rattle (Rhinanthus)—a grass-taming hemiparasite
radish
turnip
flax
asters
crocus
daffodil

This “soft corridor” weakens the grass without killing it, and acts like a crack where diversity enters.

Wood + leaves + shade-creating plants = the simplest long-term solution

Here’s the lazy formula that has transformed my own grass problem spots:

Logs + leaf piles + perennial shade = 90% less weedy grass.

Logs invite fungi.
Leaves keep moisture and cool roots.
Shade disrupts spring vigor.
Everything else follows.

You don’t need perfect plans. Just gentle, continuous gestures.

I carry logs, leaf piles, and plant starts when the mood strikes. Over time, these slow, soft interventions have turned monoculture grass into a lively polyculture.

You can start with one log, one leaf pile, one rhubarb crown. The system will build itself around your small actions.