Why are weeds growing in my rock beds?

jason91230July 18, 2014

I live near Pittsburgh and last summer we did landscaping around our house. We killed the grass, laid plastic landscaping barrier over it, planted shrubs and filled the area in with decorative landscape rocks.

However, a year later, the thing is over-run with weeds. I knew there would always be some weed-pulling involved but this seems uncontrollable. My brother-in-law (who is no garden expert) says because we don't get our yard professionally treated and there are weeds in our yard, the roots and seeds get blown into the rocks and that's why we have so many weeds. He lives 3 miles down the road, gets his yard professionally done and has 0 weeds in his rocks. Could he be right?

So, my questions are:

1. Why are so many of these weeds growing?
2. What is the easiest way to get rid of these weeds other than hand-picking them which honestly would probably take about 20 hours.
3. How can I prevent future weeds from growing. I look at my neighbors' rock beds and there are never any weeds at all. Is it because they treat their yards?

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hortster(6a, southcentral KS)

A guess as to why weeds are growing in a freshly rocked bed over weed barrier - in order for the weeds to grow on top of the weed barrier there has to be something to root into. Did your gravel have a lot of "fines" or was it dirty? Sometimes gravel piles are stored adjacent to open areas where weed seed can get blown into it.

About the only way to avoid hand picking is to carefully use glyphosate (Roundup) on a calm day with very low pressure in the sprayer, using a coarse spray so as not to get misty drift onto good plants (which it will damage or kill).

Then you can use a pre-emergent weed control that prevents weed seed from completing germination.

Having said all that, rock is seldom the labor saver that it is touted to be. Even with clean gravel, over time airborne dust settles and leaves get in there in fall, gradually building up on top of the weed barrier, providing a germination zone for weeds. A good 3" to 3-1/2" wood mulch with no weed barrier has always kept my weeds to a minimum and greatly lessened my use of weed preventers and killers, as well as reduced my water bill.

Good luck with your situation!

    Bookmark   July 18, 2014 at 2:21PM
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Kimmsr(4a/5b-MI)

Over time dust from the air, as well as bits of organic matter, will settle in the spaces between the stones and that will provide a place for unwanted plant seeds to grow. The get there by the wind and birds, mostly. Whether you have "weeds" growing there or not has nothing to do with whether the work was done by "professionals" or not, although maintenance might be a factor if those "professionals" pollute our environment with plant poisons.

Here is a link that might be useful: About glyphosate

This post was edited by kimmsr on Sat, Jul 19, 14 at 7:30

    Bookmark   July 19, 2014 at 7:28AM
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awakener

I have two quarts of alion pre emergence herbicide I want to sell. Text 912 226 6061 if interested

    Bookmark   July 19, 2014 at 10:29PM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

People who use rock mulch are constantly complaining on these forums about weeds growing in the rocks. The uneven surfaces of the rocks apparently 'trap' more wind-blown seeds (and leaves, any debris around.)

    Bookmark   July 21, 2014 at 9:29AM
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dbarron(z7_Arkansas)

Nature hates a vacuum and will colonize.

    Bookmark   July 21, 2014 at 9:35AM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

Forgot to comment about this part, "3. How can I prevent future weeds from growing. I look at my neighbors' rock beds and there are never any weeds at all. Is it because they treat their yards?"

If my neighbors don't look outside during the few minutes it takes to walk around the yard once in a while to spot and pull any unwanted sprouts, they might ask the same question. I have no weeds because when I see something I didn't plant, I pull it out, and don't own any garden chemicals. Tiny sprouts are easy to spot and pull, looking for them and doing the pulling is something that is never finished though some locations do get a break for winter.

    Bookmark   July 22, 2014 at 9:25AM
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lazy_gardens

1. Why are so many of these weeds growing?

Because there is enough dirt between the rocks and the plastic (which you will regret very soon) to germinate

2. What is the easiest way to get rid of these weeds other than hand-picking them which honestly would probably take about 20 hours.

Carefully spray them with glyphosate, according to the directions on the container, shielding the shrubs from any spray (drop a cardboard box over them while you spray). " Eliminate" brand from Walmart is a generic glyphosate that's economical. Don't buy the premix "Roundup" - they carge lots for basically water.

3. How can I prevent future weeds from growing. I look at my neighbors' rock beds and there are never any weeds at all. Is it because they treat their yards?

Prevent them from going to seed in your yard ... the first couple of years you really have to keep up with the weeds, then it tapers off. And get the weeds when they are small sprouts ... a couple of rounds of spray early in the season does more than fighting mature ones all summer.

    Bookmark   July 23, 2014 at 12:10PM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

Using chemicals as an ongoing maintenance plan is not a responsible one.

    Bookmark   July 24, 2014 at 10:39AM
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lazy_gardens

Purpleinopp ... Using chemicals as an ongoing maintenance plan is not a responsible one.

So are you volunteering to pull weeds?

    Bookmark   July 26, 2014 at 4:14PM
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Kimmsr(4a/5b-MI)

Spraying plant poisons on the weeds growing among those rocks will kill those plants and cause them to fall down between the rocks as organic matter giving seeds a nice bed to germinate and grow in, meaning more "weeds" next year. Eliminating the growing media, the soil, that is accumulating between those stones will provide a longer term solution then spraying plant poisons will.

    Bookmark   July 27, 2014 at 7:18AM
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Tiffany, purpleinopp GardenWeb, Z8b Opp, AL(8B AL)

"So are you volunteering to pull weeds?"

Thanks for the offer, but I'll pass. Willing to help you examine the situation and devise a plan though, more than. If you are serious about doing anything but spraying, I'll be happy to take time to discuss it.

We're so close! No single approach will keep any location weed free, and I think we're all smarter than a bunch'o'weeds. Let's sort this out.

"Prevent them from going to seed in your yard ... the first couple of years you really have to keep up with the weeds, then it tapers off. "

Absolutely! If one has annuals that can be kept from making new seeds, that should reduce next years' invasion drastically. Especially in a new bed, a crop of something unexpected can come up much too numerously for many people to have time to pull individuals. That's not even necessary if the plant can be prevented from making seeds by other means, like weed-trimming during flower formation time, smothering, hoeing, depends on what it is, where it is, but doing something that prevents new seeds from forming is necessary to prevent a repeat.

When starting a new bed, I try to keep the planting sparse, so I can see well what is sprouting. Not starting more new bed area than one has time to monitor is helpful. Taking the time to use a degradable smother like newspaper or cardboard is worth it in time saved dealing with weeds later.

And get the weeds when they are small sprouts ... "
Yes, still on the same page. These are easy to pull, disturb the soil surface so they die, smother, step on them, depends on the particular weed and bed type.

"a couple of rounds of spray early in the season does more than fighting mature ones all summer."
Oops, we've diverged. When I first saw unwanted sprouts, out they came, while small and it only took seconds. If you're "fighting" weeds with chemicals "all summer," and I'm weed free after pulling/hoeing/smothering those little sprouts from a single effort, who's working harder? IDK but it sounds like I've spent less time and effort. It's too hot to battle weeds in the summer here, and you probably feel the same way about where you live. I'm not trying to chide you, just help you ask yourself some questions, and hopefully spend less time, effort, $, and get better results.

What are the weeds? If spraying kills them, why are they there?

What you do is up to you, but be honest about the results you're getting from your efforts. Been reading it for so many years, those who keep using RU are the ones who keep 'battling weeds.' Anyone who is spraying anything a 2nd time is working harder than I do, simply by stepping outside the 2nd time.

Never been there, but in the baking desert of AZ, how much unwanted growth can there be? I manage w/o chemicals in AL, near FL border, living next to the pic below for years. (The bare spot is from where the abandoned house was finally torn down the day I was taking these pics.) ...

    Bookmark   July 28, 2014 at 10:46AM
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