Garden School:


Garden School:
Teaching this week: Rose pruning (as always!) and water management

Wednesday, 29 May 2013

Cow Parsley spoiling a Wildflower Meadow

One of my Clients has a wildflower meadow, in what used to be a tennis court at the back of their formal garden.

It is a charming place - well hidden behind high Yew hedges on the house side, and shielded from the neighbours by good hedging on the other sides. As well as the wildflower meadow, it contains the bonfire heap, the compost heaps, a massive Black Walnut tree, several shrubs at odd places (just to break up the area, my Client says), the rhubarb bed and the raspberry bed.

So I spend quite a lot of time there, one way or another, but I don't do much actual gardening in it.

Two summers ago, I noticed some cow parsley was sneaking in to one end, presumably encroaching from one of the gardens on that side. My Client wasn't too worried, as it was frothy and quite attractive.

Last year, however, it was smothering the wildflowers, and the Client agreed that something had to be done.  We decided (I say that, when I mean "I suggested, and my Client agreed...") that this year, we would spray with weedkiller early in the season, hoping to catch the cow parsley before the wildflowers got going - if any were left, that is!

Of course, this year turned out to be the coldest, wettest, horrible-est winter on record, followed by a non-existent spring, with temperatures so low that there wasn't much point spraying. I finally managed to start spraying a couple of weeks ago, using Verdone, a lawn weedkiller, that won't kill any remaining grass, but should - allegedly - take out the broad-leafed weeds.

I had concerns about the Verdone killing the wildflowers, but found two points to reassure me that it was right to use it - firstly the wildflowers shouldn't appear until late spring/early summer, and secondly there were whole areas last year with no signs of wildflowers at all,  due to the smothering by the cow parsley.

On the worst areas - round the Walnut, for a start - where it was a sea of cow parsley, and nothing else,  I just sprayed the entire area, on the grounds that there were no wildflowers at all there. In other parts of the meadow, I tried to "spot spray" to just target the cow parsley.

Did it work?

Well, partially - it was clear that some of the cow parsley plants were suffering, as they were growing pale and contorted.

Diversion: in case you didn't know, most weedkillers these days are hormonal, they kill the plant by forcing it to "overgrow" and exhaust itself.  So instead of going brown and shrivelling up, they explode upwards in weird curly shapes, then collapse and die.The weedkillers that make plants go brown and shrivel up are defoliants - the paraquat types - which seem to have a really fast effect, but which usually don't kill the root, so if your problem involves weeds with long root systems (bindweed, couch grass, ground elder, the usual suspects) then it is only a short-term fix. End of diversion, please continue.

However, they were still flowering, which means that they will set seed, which means the problem will be multiplied next year, so I had to take further action.

Now, in the formal garden, I just weed out the cow parsley using my standard in-constant-use hand-tool, the Daisy Grubber, (for more info, read this article) which looks like this:

...and on days when the soil is slightly moist and soft, they come out really easily, in fact, they can sometimes just be pulled out, by hand.

But there are way, way too many of them in the meadow to do that - it would take me weeks to go over the whole area, and I have the formal garden to maintain as well.

So I have adopted a new tactic: pulling their heads off. (To be pronounced in a west country growl, "Purrll theirrrr bluuudddy 'eads orrrf!")

Here's the narrow strip between two of the mown paths: as you can see, mostly just meadow buttercup and a smattering of cow parsley:


This is "after": all white umbrel heads removed.



It took me about ten minutes, instantly improves the look of the area, and will reduce the amount of seeds produced.

My plan is to spend 10-20  minutes out there each week, doing the same, to keep this area completely clear, and to gradually work my way into the other sections.

Cow parsley - Anthriscus sylvestris - is a perennial, unfortunately, which means this is not a lasting solution, as the roots will regrow.

But, my plan is that a) it will drastically reduce the amount of seeding and b) next year, hopefully it won't be quite so cold for so long, so I will be able to get out there with the Verdone much earlier in the year.

I'll let you know how it progresses!

6 comments:

  1. thank you that is really helpful, I have a similar problem, dominant Cow Parsley - lovely though it is, the quantity is too much.

    Patricia

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  2. I have the same problem in my wildflower meadow, and have decided to cut the heads off and then weed out when the ground is softer from rain, thank you for flagging up this problem and your useful advice.

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  3. Hi Patricia,

    I just wish there was an easier answer!

    You probably already know this, but when you come to the pulling-them-out phase, a good technique is to grab the stem as close to the ground as you can (rounding up all the leaves etc into a bundle), bend your knees, brace your arms against your knees and straighten up. Less stress on the arms, and if you do it smoothly, more chance of getting the whole root out.

    I got a lovely long Dock root out the other day - hmm, must write about it. *frantic typing sounds*

    Rachel

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  4. I know this problem very well. We have a few acres, and 20 years ago it was pretty diverse, but over the last 15 years or so, a neighbour has been mowing it for haylage which is great for tidying it up, but the pits for wild flowers. We also have an area that has become "infected" with cow parsley. Like you, I pull as much up as I can every week to avoid the seed setting. I've been wondering which weedkiller to use (which is how I found you), and tried SBK this year without much success. It slowed them for a week or two before they rampaged onwards and upwards again. SBK is for broad leaved weeds and I find it very good for nettles and docks. I'll be interested to hear how you get on.

    Incidently, we've been sowing wild flower seed to reintroduce some diversity, but I think it will need to be in combination with later mowing for the flowers to succeed,

    Andy

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  5. Hi Andy,

    Well, mixed success - I'm not that impressed with Verdone, even though we applied it rather more than the recommended number of times per year. This spring we had quite a lot of Cow Parsley regrowth, not so much in the problem area under the walnut, but all over the meadow.

    Because of that, I recommended to the client that they have the whole meadow mown off instead of letting it grow, as last year we had virtually no wildflowers at all - they were all choked out by the Cow Parsley. It's now June 2014, and it looks like a very poor lawn!

    The good news for you is that once you stop mowing, the wildflowers will/should come back, as there should be a bank of seeds in the soil.

    If you only have one area that is infected, I would (I can hardly believe I am about to say this) suggest spraying it off with glyphosate to kill everything above ground. This drastic action won't affect the soil or the seeds in the soil, but should get rid of the cow parsley. You will need to keep a close eye on the area for re-growth - there will be cow parsley seed in the soil as well, of course - and you might need to spray it again a couple of time through this year. If you can bear to leave it bare for this season, then in autumn you could scatter some of that wild seed mix in the bare area, work them lightly in to the soil, and with any luck next year you'll have a good covering of wildflowers there, which will then seed over the rest of the area.

    And take a daisy grubber with you on your daily strolls around the area, and weed up any new Cow Parsley growth!

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  6. Our cow parsley isn't so dense that it chokes out the wild flowers, it's been the annual mowing that's prevented the flowers from seeding and they've gradually disappeared. The cow parsley seems to seed earlier and often before the mowing which has led to their success.

    I sprayed a few of the cow parsley with glyphosate earlier this year, and they died back so I think my preferred solution is to grub out where I can, paint on glyphosate early in the year where it's impractical and continue to remove flowers that make it. It might take two or three years to get the number down significantly, but it will minimise the amount of glyphosate and its unwanted effects on the rest of the plants.

    And as for the wild flowers, I'll sow some of the seed mix next spring... or will it help to sow them once we've been mown this summer? You can probably tell I'm not the gardner of the household!

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