Monday, 27 February 2017

Elimination of ground elder and accompanying ‘annual’ weed.

Cathi’s grass verge, year 2 - weed control throughout 2016
A continuation of the saga of this developing garden feature - introduced for this year last month

No sign of the ground elder at daffodil time
Preamble
Imagine you were eliminating overgrown perennial weed by repeated glyphosate spraying on un-cropped land with the intention of direct planting when and only when that weed was completely eliminated. It would depend on the weed how long you would need to wait before any planting. I will assume, that the weed root system starts intact and you are not following failed attempts to fork it out (when it will take longer). I will also imagine that you start your project when the weed has strong growing foliage as did Cathi’s ground elder in May 2015.
 * Docks should be gone in a season although the soil will still have a large seed reserve
 * Cathi’s nettles were gone by mid summer but I have known it to take longer when the nettles were extremely well established. Glyphosate might need to be  a strong 1 in 40  dilution of commercial product. I often use MCPA instead
  • Couch grass is a breeze - give it three months
  • Brambles will take a couple of years unless supplemented by physical removal. (Cutting back helps if used a week or so after the first spray). Other brushwood killers or MCPA might be better. When rid of the bramble plants watch out in later years for the soil’s bank of blackberry seed ‘trying again’
  • Convolvulus (bindweed).  Timing of spraying is crucial - July might be ideal - and growth must be strong, soft and luxuriant. Roots need to be undisturbed and the glyphosate applied at 1 in 40. A single spray might then be sufficient to completely kill it. (Although a second application a month or so later in case some has been missed is advised)  Sadly most gardeners are temperamentally unable to take this advice and never get rid of this weed when they insist on just pulling it out.
  • You need to read my post on marestail and you will be doing well for it to be completely gone after three years.
  • Ditto  Japanese Knotweed 

Ground elder, the dominant perennial weed in Cathi’s border might be expected to be eliminated sometime in its third season. If not completely killed it is perhaps more insidious than any of the above weeds in infiltrating herbaceous perennials. Many gardeners find they have  given home to a menace when accepting an infected plant - a real Trojan horse - from a so called friend.
It might therefore seem highly foolish of me to have started planting for Cathi in the second year (2016) of the project. I do not recommend it for the inexperienced gardener or anyone who does not have total confidence in their precision use of glyphosate as I do!

 The fact that most of my planting was upright monocotyledons like this agapanthus makes it is easy for me to selectively spray. Note the withered ground elder that had been earlier sprayed

Three weeks after May 2016 spray. Note I have as yet done little planting where the ground elder had been thickest   
I attempt to present this post today in such away as to be of value to the gardener who is merely eliminating ground elder. Please regard my attempts to establish grass and plants in parallel as pure serendipity. Although you might watch in horror I am confident of my final destination. Details of the garden plants and the grass elements of the project will follow in a further post in a few weeks.

Weeds from seed
Please excuse my indulgence in the main title calling them in the popular fashion, 'annual weeds'. In truth they may be annual, biennial or perennial.
Whenever you have a project involving repeated spraying and your original target weed subsides, space is created for weeds from seed to establish in their place. Released from inhibiting influences to germination such as lack of light they germinate everywhere. You must increasingly turn your attention to controlling them too.
Soils contain enormous banks of weed seed. For those weed seeds more deeply buried some can remain dormant for many decades, others much longer! Generally if such weeds are not brought to the surface by digging those weed seeds already exposed under your sprayed-off canopy will be hugely diminished after a few years of sound weed control. Unfortunately the seed store is frequently refreshed by new seed that blows in or - more shamefully - those weeds you miss and let seed!  
Not for nothing the old gardeners’s dictum “one year’s seeding, seven year’s weeding”

The aim in all my own gardening is by keen attention to not letting weeds seed is to build up ‘a cycle of virtue’ with weed control becoming easier as each year passes.
Eventually in Cathi’s project ground cover grass and plants will also suppress newly germinated weeds.
Do I hear “dream on?”

Resumé of Year 1,  2015

I had waited until mid May to make sure that the ground elder and nettles could make a luxuriant top before my first spray. 
As anticipated most of the weed turned yellow and the tops died. Six weeks later there was fairly strong regeneration and I sprayed a second time.
For practical purposes this was the end of the nettles and the ground elder was so subdued that for the rest of the year it might have not been there. 
Any germinated weed seed and missed or regenerating perennial weed were picked off by a couple of later quick spray arounds - spraying only the weeds, no need to spray bare spaces.
Spring bulbs were planted in early September. Although at this time the ground elder was not superficially apparent if you examined below the soil surface numerous strands of ground elder roots were laying down fat buds for the next year's campaign. As far as possible when planting I avoided placing bulbs and plant divisions amongst ground elder.
There was substantial  popping in of plants throughout the Winter 2015/2016

2016 report
My last post about the progress of the project was in March 2016
By then I had been popping in plants since the previous October and continued right through the Winter when planting conditions were opportune. Just ten minutes here and ten minutes there. Perhaps a total of 15 man-hours as I raided my garden! The fact that the plants were mainly dormant at this period and were planted at the more weed free stations created no extra problems for weed control.
During the Autumn and Winter I had wandered in with my sprayer two or three times to catch those awkward annual weeds such as hairy bittercress, cleavers and epilobiums that insist on germinating at that time. By then I had merely added the verge to my normal weed control routine for spraying the whole of Cathi’s garden which I have been maintaining for three years now. In total the extra time was no more than a single man-hour spraying.

Just about ready for first spray of ground elder mid May 2016
Ground elder looking sick several weeks after spraying
It took a firm mental effort to not spray the re-emergent luxuriant ground elder too soon when it was too small. Before mid May would be too early and counter productive.  Although the border had looked good with a succession of snowdrops, crocus and daffodils it was by then very weedy indeed. A new gardener would have probably despaired and might have abandoned the project and started forking - how sad. Superficially the ground elder seemed as bad as when I had first started - and all those extra Spring weeds from seed too! Trying and inevitably failing to fork out out would reinforce future problems as lots of small ground elder propagules would be created. Forking out would create separate ground elder plants with little rhyme or reason as to the time and place of future emergence.
It took all my experience to selectively spray the border. It took more than an hour of low pressure selective spraying holding the knapsack nozzle almost touching and carefully directed. It was made easier that the new growth of ground elder followed a pattern as the still connected roots had sprouted together. I had previously mainly avoided planting within the ground elder clumps. Inevitably where the ground elder had spread into the already grassy part of the verge there was collateral grass damage. The consequent bare ground would facilitate spraying of persisting  ground elder that re-emerged in the same place later in the season.

For the rest of the year I just sprayed as necessary as part of  my normal spraying routine for the whole garden. No more than a total of a couple of man hours. For practical purposes the by then weak growing ground elder had become ‘just another weed’.
Although substantially weakened, some ground elder will sporadically appear in 2017. It will be zapped just like any other weed.
I have written before about when I eliminated half an acre of a monoculture of two foot high ground elder on the village plot nearly ten years ago. Each year I still find a rare sneaky specimen. 

I might give the  impression that my weed control is only spraying. For Cathi’s verge this is substantially true. I do reserve the right when popping-in plants or just walking and day dreaming to bend my back and pull a weed out or skim my spade or slide my boot to detach seedling weeds. There are so few it is pure pleasure.

A few further glimpses of last year

Only when these snowdrops have completely died down will I spray over them

Camassias are one of the few bulbs traditionally planted in grass. The forget-me-nots scattered after the very first spraying are proving remarkably persistent 
Spraying is a little tricky here

I took on a further ten metres verge last year. Self sown poppies appeared after my first spray

The same extended area. I am pleased how well the agapanthus planted a few months earlier established. The blue commellna are going to have a field day

Although tulips do not have enough vigour to naturalise in coarse grass I expect them to thrive here

With patches of ground elder still around my effort to establish fine fescue grass has been as yet only half hearted 

There is still interest in mid September. At that time I anticipated the imminent wet spell by making a more determined sowing of Chewing's fescue grass seed
Mid february 2017. Somewhat scruffy but even Brenda admired it when we drove down the road

Links
There is now quite a saga about Cathi’s verge in my theme column
My post on controlling Japanese knotweed
Marestail (equisetum)
Bindweed (convolvulus) scroll to the end of this post


2 comments:

  1. The snowdrops are lovely. I find it amazing as to how many years some weed seeds remain viable in the soil. I've read thirty or more years! Don't field poppies need the soil to be turned over in order to germinate?

    ReplyDelete
  2. Certain seeds much more than thirty. You have probably read about poppy being brought to the surface and germinating perhaps even after a century! Those already at the surface and deprived of light by the ground elder in Cathi's garden do not need to be shifted!
    I would seem that Cathi has liked this variety in the past and now it appears all over her garden (Where I let it!)

    ReplyDelete

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