Help eradicate grass in my garden

July 19, 2008 2:28 PM

My garden is being overrun by grass. How do I get rid of the grass but keep my existing perennial plants?

We bought our house in late 2005, so this is our third summer in the house. The previous owner was an excellent gardener, and took good care of it until she had a stroke a few years before we bought the house. Our house is 30 years old, and I believe that our lengthy perennial border garden has also been established for 30 years. The garden is bordered by the lawn on one side and by concrete stairs, a rock retaining wall, or gravel driveway on the other side.

When we moved in, the garden was overrun with grass in areas. So far, we've done an annual "big dig" around existing plants to get some grass out, and then did a half-assed job of planting. Sometimes we didn't do much grass weeding throughout the year. This year is the first year that I've had the time to continuously make an attempt to keep up with the grass.

I hand weed so I know that there is an extensive grass roots system under the ground. I don't use tools to weed because the grass is intertwined with the plants - namely the columbine, lobelia, and rudbeckia (I'm pretty sure that the first two plants with grass have columbine and lobelia, anyway). All three of those plants seem happy enough to grow, and they're attractive enough to keep, but the grass is ugly as hell and I have no idea how to get rid of it without spending 2 hours a week weeding, which sucks.

I would like to solve my grass problem. Using Round-up or tarp/mulch to eradicate the entire garden is not on the table - I'd like to keep the good plants in the ground, as I also have fuschia, heathers, foxgloves, blanket flowers, tiger lilies, forget me nots, irises, a 20 foot dogwood tree, miscellaneous shrubs, etc in there in various places. Do I have to pull out the weedy plants? Do I need to divide the rudbeckia and get the grass out somehow before replanting? Is there a better technique for weeding - can I use tools if there are spaces between the plants? Do I need to fill in any/all spaces in the garden with grass resistant plants or mulch/bark? Do I need to hire some kind of garden consultant to check out my garden in real life and give me advice? What do I do?

Constraints - I am willing to spend up to 3-4 hours per week on maintaining this rehabbed garden, and I would rather prune than weed. I prefer not to invest a ton of time into special projects (ie, I'd like to integrate garden rehab into a weekly maintenance schedule with only 1 or 2 times annually of more work). I am willing to spend $500/year on my garden, and I've spent $150 of that so far this year. I am a novice gardener so I don't want to get too fancy.

If you have general plant suggestions for a grass-free garden, post them here too. Zone 7b, north-facing garden with a later start than most Pacific Northwest gardens (my tulips tend to open a week or two later than other zone 7b tulips), sun/part shade/shade in various spots. The part shade/shade areas are complicated by either (a) being on a slope or (b) being under a large dogwood tree with an extensive root system, so only shallow shade-loving plants can be accommodated. I prefer perennials or self-seeding annuals. Cost and maintenance constraints above. Thanks

posted by crazycanuck to home & garden (14 comments total)

Maybe you could plant some ground cover (such as ivy or creeping phlox) that will squeeze the grass out.
posted by matty at 2:43 PM on July 19, 2008

I think what you need to do is learn how to use a hoe. (I'm completely serious about that.) It's fast and efficient. Once you've hoed an area, then you use a garden rake to clear all the grass/weeds out which you cut loose with the hoe.

It's a lot faster and easier than hand-weeding. (That's why the hoe was invented.) But if you've never used one before, you'll probably use it wrong. The goal isn't to cut off the weed at surface level. You want to cut it off well under the surface.
posted by Class Goat at 3:17 PM on July 19, 2008

I use tools...sharp, big, whatever is called for to get the job done. To get rid of extraneous grasses and weeds, dig a perimeter around a plant and pull it up. Pull out all of the grass interspersed in the plant, and clean the soil all around the area and replant. Best to do this when ground is pretty wet since digging as well as removing grasses is easier then. Ideally you'd do all of this toward the end of the hottest time of the year. Mid-September in your area, maybe? Starting at one side of your planted area and working over, you can clean by sections. If the plants are pretty well established (a couple of years or more), after replacing them in their holes, water them in well, give them a week or so to reestablish themselves in the ground, and then you can follow by sprinkling Preen around and between all of the de-grassed areas. Preen will inhibit the regrowth of grasses and weeds. You could also mulch 3 or so inches of bark following the Preen, as you move across cleaning up the area. Mulching is helpful...but you may like the barer look between the plants as I do. There are pluses and minuses to either method. I'd clean out again in the spring, as soon as the grasses start to regrow, sprinkle Preen again, and then maintaining the clean look should be pretty simple...reapplying Preen once or twice yearly and pulling stray grasses as they crop up. Don't be afraid to be firm with the plants ; ) Once established most, particularly perennials, are quite resilient. Tools are fine and as long as you dig into the ground 6-12 "away from the center stem/trunk/whatever, cutting the outside roots is fine. I recently dug up a wisteria and had to slash through several large roots in doing so...it looked quite spent and dead for a few weeks and now has myriad leaves sprouting everywhere. It's hard to kill perennials...as you've noted in trying to erradicate the grasses!
posted by mumstheword at 3:17 PM on July 19, 2008

Do I need to fill in any/all spaces in the garden with grass resistant plants or mulch/bark?

This is where I would start for your garden and is what I've done in my own. Use bark mulch or similar layered over paper so that it all breaks down and fertilises the garden and don't be afraid to spread it right it underneath the overhanging branches of the ground cover plants you already have (so put it right up to the stems) so that every bare bit of dirt is covered. You'll need to refresh it every year or so as the old mulch breaks down, but that's generally a good thing for your garden anyway (adding organic matter and all that).

Do a really thorough, aggressive weed first, targeting roots as well as leaves, and continue with regular weeding to get any new grass that pops up. It will probably take a season to get things really clear but you should be able to greatly reduce the amount of maintenance necessary to keep the grass and weeds out while not affecting the wanted plants at all.
posted by shelleycat at 3:19 PM on July 19, 2008

Yes, use a hoe. They work.

You should use some type of edging or border material where your borders meet the lawn. Either rocks, stones, logs, or if you want something less visible, use plastic edging. You'll need to dig a little trench and fill in with your border material. Here are directions for installing plastic edging. The grass I have grows on runners. If I make regular visits to my borders I can pull them out by hand without much hassle. Sometimes if I have been a little negligent and have a patch of grass that I don't want, I hack it out with the sharp hoe end with a tool like this. I use the sharp side to hack it up and pull hunks of grass out with the rake side, or use my hands. Most grass is aggressive and will eventually make its way over, through, and under your edging material. Edging material will decrease the amount of grass creeping into your borders but you'll still need to keep on top of things and attack when needed.

Definitely mulch. Use pine straw or dead leaves or some other organic mulch that doesn't rape the environment (such as cypress chips.)

If you have a lot of pesky grass around inexpensive plants you might want to rip that particular plant out and start over. If you don't want to get rid of any plant, you'll need to get on your hands and knees and gingerly start eliminating the grass. Brake it up with a spade or some other tool, like the one I mentioned above, and dig it out, being careful to avoid the roots of the plants you want to keep.

Ideally, you'll want to get rid of anything green in your beds besides your desired plants because green plants use rob nitrogen from the soil, or something like that. You can leave dead material unless it is infected with something that is undesireable.

I rarely use Roundup either because I have too many valuable plants nearby. It's not easy work, but ripping out sod is therapy for me. I have ripped out entire 20 foot borders only using the hacking tool and a square point shovel. It's nice physical work and your mind is focused on the task at hand.

You can also use landscaping blackout material to control grass and weeds. I use this in my front beds where everything is picture perfect and suburban, but I don't use it in the back borders because I have a lot of plants packed in there, and I often replant and change things, so it's not that practical. Use blackout material where you can. It really does help.

Once you get rid of the invading grass, make regular (ideally daily) trips to your borders so things won't get out of hand. If you have 3-4 hours a week that should be sufficient time to make a morning walk through, pull some weeds, do some deadheading, notice what is and isn't thriving, etc, and hack out some invading lawn if need be.

You might look into the heart hoe. I've heard good things, but don't own one.
posted by LoriFLA at 3:40 PM on July 19, 2008

When we converted a patch of lawn into a garden bed, we turned the grass 2' underground. Turf is tough stuff, you're going to have trouble killing it without hurting the rest of your plants.
posted by anthill at 3:45 PM on July 19, 2008

If you have a lot of pesky grass around inexpensive plants you might want to rip that particular plant out and start over.

Or replant, as mumstheword suggested. No need to throw the plant away. I didn't word that very well.
posted by LoriFLA at 3:50 PM on July 19, 2008

1.) Get one of those disposable foam paintbrushes at the hardware store.
2.) Get some Roundup. On a non-windy day, mix up a small container.
3.) "Paint" the Roundup on your grass with the disposable brush. This allows you to target ONLY the grass, with no danger of overspray.
4.) After grass dies, mulch heavily - I like cypress bark.
5.) Maintain by hand-weeding.
posted by Ostara at 3:59 PM on July 19, 2008

LoriFLA writes "Ideally, you'll want to get rid of anything green in your beds besides your desired plants because green plants use rob nitrogen from the soil, or something like that. You can leave dead material unless it is infected with something that is undesireable."

While generally true be aware that legumes including clover, alfalfa and beans are nitrogen fixing. Clover specifically is fairly attractive, tough and low maintenance. If you've got it in your flower beds I'd leave it.
posted by Mitheral at 4:08 PM on July 19, 2008

One of the guys who literally wrote the book on organic gardening in the Pacific Northwest (I think it was Steve Solomon) said that the only effective means of control of grass that he'd found is Roundup. Just so's you know. (I just checked Growing Vegetables West of the Cascades, 5th Ed, by Solomon, and didn't find it in there--I believe it was in an earlier edition, though, with a *very* defensive footnote about it!)

In my experience, it is possible to be extremely specific in applying Roundup so that only the targeted plants die. Ostara's suggestion of a disposable foam paintbrush is good. I've had success, say, killing only the bindweed/morning glory which is twined around a desirable plant using very targeted application.

Good luck! Your garden sounds beautiful.
posted by Sublimity at 4:33 PM on July 19, 2008

Wow, these are all best answers, thanks!

So in order we have:
- Hoe and prep bed for edging
- Install edging
- Spot treatment of roundup
- In Sept/Oct, dig up nice plants, pull out grass, and replant
- Layer on mulch for winter
- Hope for luck in spring, either plant to fill in the blanks or more mulch as needed
posted by crazycanuck at 8:27 PM on July 19, 2008

Please read up a little before using cypress mulch. Other types of mulch work just as well. See if your local forestry or parks division has free mulch that you can haul.
posted by nax at 6:00 AM on July 20, 2008

Late to the party, but I use a hula hoe. It gets down where the roots are, but doesn't move the dirt around as bad. We have several large raised beds that get invaded by our crab grass lawn, so there is a lot of hoeing to do.
posted by Big_B at 7:16 AM on July 20, 2008

By the way, it's a lot easier to use a hoe if the soil is dry. When it's wet, the soil sticks to the hoe.
posted by Class Goat at 1:16 PM on July 20, 2008