ugh, weeds
May 25, 2011 9:38 AM   Subscribe

We have the holy trinity of major weed problems: Bermudagrass, Oxalis, Wild Blackberry. What should we do?

We moved into our San Francisco house in January and inherited a large, very unkempt backyard. It clearly has not been maintained for many years. We're not expert gardeners and are clearly outmatched by the weeds.

It's terraced up on about 6 levels from the back of the house up the hill We've weeded (by hand) hundreds of gallons of weeds but still have much to do and are trying to avoid using herbicides but are not completely opposed to them. The oxalis is pretty benign and though it's a pain to weed, it's not quite as obnoxious as the other two main problems. After pulling 10-foot long, inch-thick, thorny vines out of the trees, the wild blackberry (Himalaya Berry?) is still popping up all over and we've been digging it up as far down as we can but I'm sure there's still more to come. Our neighbors to the back are infested with it so I know it's just a matter of time.

The Bermudagrass is particularly awful and there is a tangled mat of runners several inches thick in places AND there's landscape/weed cloth underneath a lot of it (clearly not doing its job). I pulled up some of the weed cloth and there's MORE runners underneath it. Do we just have to scrape off a foot of soil and start all over? How do we eradicate the Bermudagrass?

Luckily, there's almost nothing in the yard that's worth keeping so wholesale destruction is fine. No fine-grain weeding is really required yet. Another difficulty is that the backyard is only accessible through the house (it's attached on both sides to the neighbors) by way of a standard-sized door so any equipment has to be small enough to get through there. A rototiller would fit but is that going to make the problem worse? Do we just need to pour poison on our yard? I don't mind hand-weeding if it's really going to help.
posted by otherwordlyglow to Home & Garden (26 answers total) 4 users marked this as a favorite
If you don't mind herbicide, then use total groundclear. Once everything is dead, rototiller the whole thing. Groundclear again, and rototiller again.

After a few months, bring in topsoil, rototiller it, and do what you want.

The other option is to rent a bobcat and scrape to top layer off everything, dump it, and bring in new topsoil and replant.
posted by rich at 9:52 AM on May 25, 2011

I'd take away as much stuff as possible and then spray with roundup. Roundup gets a bad rap because of its use in big agriculture as an ill-advised weed killer but as a broad kill-everything herbicide it's fine and reasonably safe. I had some invasive stuff in a previous yard and that was the only thing that finally got rid of it. But removing all the runners, etc is something you'll have to do regardless of whether you use pesticides or not.
posted by GuyZero at 9:55 AM on May 25, 2011

Confession: I use a bit of Roundup here and there to deal with the Bermuda grass growing in my foundation. I've read up a lot on it, and I think that on the spectrum of pesticides, it's Not That Bad. Use it sensibly (not right before a rain storm, not if you live right above a creek, etc.)

However, I'm not sure that delicate or judicious use of Roundup (aka, glyphosate) will do the trick for blackberries: It sounds like you have to use a ton of it. From the UC Davis integrated pest management blackberry page:
To obtain good control, however, complete foliage coverage (spray-to-wet) is essential; spray the plant until it is thoroughly wet but not to the point of runoff. Burning or mowing 40 to 60 days after spraying with glyphosate increases the level of control and also contributes to good pasture establishment by removing stem debris. Shoots recovering from sublethal glyphosate treatment tend to die more quickly when subjected to heavy grazing.

Repeated rototilling (not just once, which will just spread the rhizomes around) does sound like the best option for you. From UC Davis:
Because repeated tillage easily controls wild blackberries, they aren’t a problem in cultivated agricultural systems. A single cultivation, however, can fragment the rhizomes and spread the weed. Bulldozing also can cause resprouting and can spread the weed by fragmenting roots and stems.

The oxalis will die off in summer, which makes it a less onerous weed problem (at least for me). I worry about it in spring and then don't after it dies. I am (this is true) starting to like its yellow flowers. But I'm a hippie, so whatever.
posted by purpleclover at 10:09 AM on May 25, 2011

I'd use roundup then solarize for the whole summer.
posted by anadem at 10:20 AM on May 25, 2011

What do you want to grow ? Grass like fescue ? What's your time frame, budget and desired work load ?

You can total nuke with chemicals (apply roundup, twice, about a month between sprays. Apply using a pump or backpack sprayer). Or put plastic down (heard both black or clear, I haven't tried either) to kill what's underneath it. Once dead, then till/seed or sod.

Of course, you'll need to maintain the seed/sod.. Given your neighbors have a host of weeds, it will be a fight.

In theory, a well established fescue will hold its own. But keeping it well established ain't easy. (Read: fertilizers, 2,4D weedkiller, pre-emergent weed killer, put a sprinkler system in, thatch/seed, etc). Ain't cheap, is a lot of work.

And Bermuda grass is pervasive and a PITA. There are selective sprays that kill just bermuda grass. Fusanol or something like that (name/bottle isnt handy, google wasn't helpign me). Smells like diesel fuel. Will still take a few applications to kill, but safe to spray over (most) other plants.

All this to say, my grandma's wisdom was, "why are you spending lots of money on something that will only take more work" (work to maintain, mow, etc, and more money in seed/equipment/water/etc).
posted by k5.user at 10:21 AM on May 25, 2011

Oh, right.. for the blackberry, you can use poison ivy killer.. It kills woody plants.
posted by rich at 10:30 AM on May 25, 2011

Here in the south, Bermuda grass is a really common lawn grass. If you're just planning on having a lawn, maybe it's easier to have a Bermuda grass lawn?

Also, oxalis is really tasty in a salad, if that will give you an incentive to pull more of it.
posted by hydropsyche at 10:48 AM on May 25, 2011

Response by poster: We're not sure exactly what we want to do in the long term though a grassy lawn is not in the picture. I'd like some groundcover areas that are walkable and will be doing some hardscape but we also want to try vegetables and herbs and plant perennials. We just had a huge eucalyptus removed and are hopeful of getting some trees in there eventually.

As for budget, we don't want to spend a ton but are definitely willing and able to spend a good amount over the years. We don't have a ton of time, mostly weekends but don't mind doing the work.

Unfortunately, a Bobcat won't fit through the door to the backyard.
posted by otherwordlyglow at 10:52 AM on May 25, 2011

I have tamed neglected city lots with those same bad actors. There are a few things you can do. Doing it piecemeal and by hand will take a long long LONG time and probably will not be successful in the end.

Fastest route: Mow it all down to the ground, remove the cut stuff, and applying Roundup wholesale. Leave it uncovered for a couple of weeks (Roundup interferes with photosynthesis, the plants need exposure to sun for it to work) and perhaps repeat spray a few weeks later to get what you missed the first time.

Other possible routes are solarizing (as previously suggested), which is basically covering with clear or black plastic and letting the weeds roast under the sun all summer. Or smothering, which IME is best done by (a) going to Costco and getting a ton of the large cardboard flats that they use between layers of merchandise, (b) laying those out over your surface to be smothered, (c) putting 4-6 inches of compost on top. Plan on planting a few months down the line, maybe next spring. The latter option actually has the benefit of building your soil in the process.

Keep in mind you'll be after newly-sprouted blackberries from seed, or shoots encroaching from neighboring yards (these things don't stop at your property line) from here on out. Keep on top of your weeding and it shouldn't ever be a big problem like this again.

Good luck and I hope you wind up with a lovely garden in the end.
posted by Sublimity at 10:54 AM on May 25, 2011

Response by poster: Oh I forgot, we did mow down one big section and then put a tarp over it for about a month hoping to kill some of it. It seemed to help a bit but I'm not sure we get enough sun/heat to truly solarize the soil (this is San Francisco).
posted by otherwordlyglow at 11:10 AM on May 25, 2011

I have had a surprising amount of success taming blackberry by repeated mowings. It took a lot of work to get them mowable the first time, but as long as we stayed on top of it, eventually there wasn't blackberry there anymore.

However, I have to confess that I like my bermudagrass; I think once the blackberry bushes are getting mowed down repeatedly, the bermuda moves in and takes over. I'm not sure that's what's happened, though, because some areas still have sort of scanty bermuda coverage but no longer have blackberry.
posted by galadriel at 11:13 AM on May 25, 2011

Ornamec is said to kill bermuda grass. I've got it all over the back yard and if grass was all I wanted, I probably wouldn't care too much. As it is, it spreads into everything - the vegetable garden, perennial areas, driveway cracks, etc. It is a colossal headache. Bermuda grass control shows up on the gardening forums pretty regularly. My favorite suggestion so far is a tactical nuclear weapon.
posted by jquinby at 11:20 AM on May 25, 2011

I was just coming back to be skeptical of solarizing in San Francisco. I don't think it's hot and sunny enough here to work.
posted by purpleclover at 11:37 AM on May 25, 2011

Some reasonable suggestions, but there's a secret to using herbicide sprays in this scenario. Mix a little dish soap in. This will make it much stickier and more will stay on the plant. It also helps if you mow it down, them apply the herbicide as new growth appears (and do it repeatedly). As explained to me, the plant will absorb more herbicide as it's revved up pushing out new growth, and it's dipping into it's reserves.

Another suggestion, especially for things like the blackberry, is "stump killer". Look at Ace or other smaller guys; Home Depot and Lowes don't carry it. And I don't mean the stuff that makes a stump rot faster. You cut the bush close to the ground, and squirt some of this stuff on the freshly cut root. It gets sucked in by capillary action and kills the thing off. Sometimes it takes more than one try, but I've found it very effective.
posted by kjs3 at 12:00 PM on May 25, 2011

Friends in a similar situation had great luck with a flock of borrowed chickens.
posted by judith at 12:24 PM on May 25, 2011

You can also use Roundup like the "stump killer" kjs3 mentions.

I encourage you to plan what you're going to plant before you eradicate the yard. If you don't get new plants in fairly quickly, the weeds will come back from your neighbors' yards. Go to a nursery and talk to the staff about vigorous plants that will have a shot at out-competing the blackberry / plastic barriers for the top of your beds to keep the competition down.
posted by momus_window at 12:52 PM on May 25, 2011

Also you could rent goats. I think there are multiple goat rental places in the SF Bay Area.
posted by GuyZero at 1:01 PM on May 25, 2011 [2 favorites]

Response by poster: We did look into goats and it's still on the table, but they'd have to herd the goats through our house to get to the backyard and I think they wouldn't do much about the underlying soil problem (roots, rhizomes, etc). Plus, our yard is only partially fenced so we'd need to set up a temporary enclosure and given all that, I think the price goes way up. But still, I love the idea.
posted by otherwordlyglow at 1:07 PM on May 25, 2011

Your yard is only partially fenced? I was coming back to suggest that you consider taking down part of your fence to get bobcat/etc in, but if it's only partially fenced, is there no way through a neighbor's yard?

For something like goats--much lighter weight than a bobcat--if you can't take them on a roundabout route, and you can't take the fence down, maybe you could build a temporary stile over the fence. Or put in a gate! It sounds like you might need one :)

Would a 3- or 4-line electric fence (hotwire) suffice for covering the areas that aren't fenced, so you could use goats? Those can be relatively inexpensive.
posted by galadriel at 1:29 PM on May 25, 2011

Response by poster: Nope, we're in the middle of the block and it's all attached houses - no side yards anywhere near us. Furthermore, it slopes up in two directions and all the yards are terraced. I think our neighbor uphill and to one side is going to finish off the fence soon so eventually we'll be fully fenced.
posted by otherwordlyglow at 1:39 PM on May 25, 2011

Around here as long as we cut the grass short a few times the weeds tend to die off, but, we the ones that don't we leave. But, I'm of the belief that "lawns" are a waste of time, money, water and chemicals.
posted by SuzySmith at 2:08 PM on May 25, 2011

If you get lemons, make lemonade observation:
Blackberries can make tasty jam and ,with some sieving, jelly.
•Be sure they have not been poison-sprayed as roadside blackberries probably have been.
posted by Cranberry at 2:21 PM on May 25, 2011

A tarp won't do it for solarizing. You'll needs sheets of plastic. The weave of the tarp lets too much air exchange so it won't get bakin' hot, which is the deal in solarizing.

I successfully solarized a bad lawn on the north side of a building in Seattle. SF should be fine.
posted by Sublimity at 5:58 PM on May 25, 2011

That's the great thing about goats is that it does help kill off the root. They like the leafy parts of the plant and they leave the stems alone and it kind of fools the plant. Excerpt from a goat weed control article:

"The first thing goats do when they walk through the pas- ture is snap off all the flower heads. Then they pick the leaves off one at a time, very quickly, leaving a bare stock. Once the goats graze the weed, it cannot go to seed because it has no flower and it cannot photosynthesize to build a root system because it has no leaves. The plant’s stalk and the ground is left undisturbed. The canopy has been removed allowing sun- shine to hit the ground. The goats are fertilizing the ground, and the grasses remain untouched by the goats. Our working goats know when they are done and ready for the next job.
It is well-documented in research that if you cut the stems off of most weeds with a sharp blade the plant will quickly respond by making just as many seeds if not more, actually making the plant denser. But because of the way a goat eats, the plant is stopped. It cannot make any seeds or photosynthesize. I think the plant is fooled that everything is okay, so it does nothing."
posted by no bueno at 6:52 PM on May 25, 2011

What neighborhood do you live in? I'd suggest talking to the folks at Sloat Garden Center - since they're local, they understand more about addressing problems in your particular micro-climate than the folks at a gardening department of a big-box store. I'd also suggest Lasagna Gardening as a way to knock out weeds without using a bunch of pesticides. Blackberry bushes in my experience can only be vanquished by being dug out and repeated sweeps of the area to remove any new sprouts - it can take years to get it completely under control.
posted by echolalia67 at 10:03 AM on May 31, 2011 [1 favorite]

Response by poster: I keep meaning to head over to Sloat and ask them, too. It's a pretty huge area so I'm not sure if I'm ready for the lasagna method but it is intriguing. We put the doubled-over tarp back over the worst of it and will hopefully have some less rainy weather soon and a free weekend to really attack it. We'll probably rent a rotatiller and also try to scrape off the first couple inches of soil. There's too much soil in most of the area anyway since it's all been left there self-composting for so long.
posted by otherwordlyglow at 8:37 AM on June 1, 2011

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