Monday, 14 May 2018

How to control bindweed, Convolvulus


It is many gardeners worse weed but can be eliminated by a single carefully timed spray

Bindweed, if it was difficult to grow everyone would want it
When I first wrote about killing bindweed the post reproduced below was tagged on at the end of a long boring post about glyphosate and no-one found it!

Unlike my posts about other distressing perennial weeds such as ground elder, mares tail, bramble and nettles which have been read thousands of times this post attracted no interest at all. To me that’s a shame as I think it is of value to numerous gardeners

Shame on Kew
When we visited Kew a few years ago I photographed one of their dicentras covered in bindweed. No doubt brought in in imported soil, I cannot believe that in a few hundreds year they have they have otherwise failed to control it.
It represented a typical beginners garden where any control of bindweed was limited to cutting the weed down and scrabbling away in the ground. I fear much gardening advice and product claims about ‘controlling weeds’ is at this level. Such weeds continually regrow from week to week and season to season.

When I write about eliminating perennial weeds I mean getting rid of them for ever. In the case of ground elder and worse, mares-tail, it might take a few years. Not so bindweed. It is extremely sensitive to glyphosate and if a luxuriant intact plant is sprayed the weedkiller is translocated to its strong rhizome resource and kills it.

Contrast this with attempts to physically remove the underground ‘roots’. It always fails and the gardener merely propagates the weed. Worse the weeds’ irregular regeneration inhibits future glyphosate use.

I used to think that bindweed was just a perennial weed that once eliminated did not return from seed. Peter Williams tells me I am wrong. I suspect what happens is that although most gardeners suppress it with their constant weeding they never let it get so far as it flowering or if it does they pull it out in a panic.
If you do really eradicate the weed using my methods with minimal care it will not normally return from seed.

Ironically the best time to completely kill bindweed with glyphosate is when it has just come into full flower. Many gardeners will be impatient and if it grows strongly enough might get away with spraying as early as June. It is useless to zap a bindweed shoot as soon as it appears!

Let me emphasise. If you spray it today (early May) it has not grown enough and you will fail. If you scratch away at the roots at any time and do not allow time for every single convolvulus chopped 'root' make a strong top you will fail

This is my original prose about controlling bindweed in Steve's garden

We made an unexpected visit to Steven in Folkestone. He has moved yet again! This time the house is built into a cliff on Sandgate Hill. Formerly a very fine garden, children and boxer dog permitting it might be so again if we make enough visits! Almost completely neglected for 18 months although full of fine plants, it is completely overgrown! The ten foot curtains of bindweed were absolutely magnificent.

What a chance to put my money where my blogging mouth is. I have often enough said how easy it is to control bindweed given the right conditions and every time I metaphorically hear "this man is an idiot". 
I asked Steven whether he wished to keep this lovely plant. He was rather decisive that he did not!

Everything was right for a speedy and definite kill. The bindweed was completely intact and growing luxuriantly. There had been heavy rain the previous night to perk it up even a bit more. Now dry, it was a warm and sunny. Even better it remained hot and dry for the rest of the weekend. In my opinion July is the very best time to kill bindweed.
My weapon was a small, cheap but accurate hand sprayer. The exercise was to clamber through the steep garden spraying all the leaves of the bindweed without spraying the plants. Amateurs excessively fear any spray might be misdirected onto their plants. It takes a most unskilled and careless sprayer to harm husky privet, ancient griselinia, ceanothus, hebe, any conifer and almost all large vigorous shrubs. 
You need to aim to cover at least 80% of the bindweed leaves. I managed 90% and made quite sure I did not miss a single weed. My spray was a strong one for me, 1 in 40, commercial 360g glyphosate to water - about three and a half UK  teaspoons in my litre of water.

Hand sprayer  £2.40
Technique
Practice with pure water first. Take the nozzle very close to the convolvulus leaf and gently pull the trigger. For the sprayer illustrated move the trigger only part of its travel. A complete pull in little stutters will separately spray several individual leaves. This will be the most skilled parts of the operation. All other variations in directing the spray will be quicker and easier.

I had to be careful near the rose. The conifer hedge would be almost impossible to harm!
Usually the canopy of bindweed leaves will be make its own cover over a section of your plant. Vary your direction of spray to wet them and not your plant! The bigger the cluster of bindweed, the speedier you can be.

The convolvulus was so thick here I had to lift the draped curtain to reach more leaves below!
Usually bindweed binds very loosely! Un-twirl little bundles and pull them away from the host and spray them. Even in herbaceous borders you can do this if you gently pull out the clusters of bindweed away from your plants.

Wind a cluster round your hand (you might not be as confident as I am of the complete safety of glyphosate to use your bare hands)
Often the growth of the bindweed will help to make it easy and speedy to spray. If it clambers over soil, hard surfaces, walls, old ivy, or none-green shrubby stems it makes work very easy. Great curtains tumbled down over some of Steven’s walls. It was the work of a few seconds to spray tracts of a meter!

Great swathes tumbling down
I had to be very careful where a few delicate plants grew under the shrubs and small trees. Twice I needed to pull herbaceous perennials away from the overgrown shrubs. On one occasion I cursed when I sprayed a hidden day lily. It thanked me when I tore off the few contaminated leaves and it did not suffer at all.
It is most important to tackle every single bindweed plant. In Steven’s case I had to fight my way to and even beyond his boundary to get to all of the weed.

I had to stretch to reach over the pond
In the 300 square metres of garden there must have been at least a hundred vigorous clumps of bindweed. Steven tells me that after a week they were completely yellow and were  starting to shrivel. He will see them no more this year. I am completely confident that 90%of this bindweed will not appear again. The few plants I might have missed will be eliminated next year. It took me less than two hours for the complete operation. I needed one litre of diluted spray.



Was it my imagination that when we departed Sunday lunchtime that this convolvulus growing over the jasmine was starting yellow

Wear your normal garden clothing when doing this work. You might wish  to use waterproof gloves. Remember not to grab desirable plants with wet hands!


Two further visits to Steven’s garden
We returned in October - to sort out the pruning. There was no sign of any bindweed whatsoever. There was some insignificant browning on a few of the shrubs. No more than that caused by a stiff wind or a touch of mildew and all easily pruned out. (Actually as a result of the shrubs previously untamed nature massive  amounts of vegetation were pruned away!)

We returned the next June, eleven months after my original spraying. The only sign of bindweed was a a few strong shoots in a few very obscure places which I had previously missed.

The following September Steven and Haley moved!

Last thoughts
The method I have described works very well in shrubs and hedges and open ground. It is more tricky in herbaceous borders where your plants are more sensitive to misdirected application. It needs a little more care, especially early in the season when herbaceous perennials are particularly vulnerable. I find it works very well if you carefully twirl out handfuls of long bindweed shoots and spray each little bundle. Even better if the still attached shoots can be teased away and laid on bare ground.


Regular readers will note I have abandoned my beloved knapsack sprayer for this weed The small hand sprayer is much better.

All that trouble and yet at home I am growing this close relative ipomoea 

6 comments:

  1. i’m always removing bucket loads of roots as using your method on an allotment would be tricky and with neighbouring overgrown plots harbouring the stuff which flowers profusely stopping seeds spreading is impossible. Bizarrely I find removing it and following those fleshy white roots to their source to be rather satisfying - sorry!

    ReplyDelete
    Replies
    1. It's what turns you on that matters Sue
      Do you actually notice any coming from seed? I imagine it is difficult amongst all your convolvulus root cuttings to discern them. I am genuinely interested how well they come from seed. (as opposed to the seed born annual climbing polygonum also called bindweed)
      If it was me I would offer to get rid of it for your neighbours but perhaps they do not approve of weedkiller
      I imagine the convolvulus seed does not spread very far.

      Delete
  2. Good Morning
    I encourage any bindweed I encounter to grow up a long bamboo cane placed next to it and twine any shoots up cane and disentangle shoots from plants, then when bindweed is in full growth and flower slip the tangled mass ff the cane and place in large bin bag and spray, when spray has dried remove the bag - used to protect neighbouring plants - and then over the next week just watch the bindweed die!
    If I encounter a large bed over growing plants I have been known to disentangle bindweed from the plants I want to keep and cover these with bin bags and then spray the whole bed, leaving it looking like a modern art installation whilst spray dries!
    I am sorry I'm an infrequent comment leaver, but would like to say I do enjoy reading ( and inwardly digesting) your posts
    Many thanks
    Bridget

    ReplyDelete
    Replies
    1. Thanks for your helpful comment Bridget and pleased you enjoy my posts.
      I think for vigorous shrubs it is a bit fiddly but I know it works very well and will be helpful to readers - especially the bit about watching bindweed die!

      Delete
  3. Great and informative pos, thank you!
    Can you tell me at what point did you remove the dead bindweed?
    I have just found some bindweed in my garden :(
    Many thanks

    ReplyDelete
    Replies
    1. Never bothered on Stevens Nic!
      If you want rid of the unsightly yellow and eventually brown leaves perhaps ten days after spraying - unless the leaves are still green which would indicate a wheel had come off!

      Delete

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