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advice desperately needed on the evil that is alkanet/pentaglottis
I understand this creature of evil can be called "green alkanet", or "pentaglottis." I have a few other names for it. Here is my story. If tdlr; please give me your advice on controlling alkanet. I know it might take years, if ever, for it to be removed, but I'm worried I'm making it worse, and that it's getting uncontrollable.
I recently moved into a flat where "maintaining" the medium-sized garden is part of the tenancy. I bring to this role a complete absence of gardening experience, a lack of natural talent (one might say even anti-talent), and a tendency to shriek at the sight of worms.
The previous tenant must have let it go for years, since alkanet owned that garden. It fully covered the beds. The beds are almost entirely empty apart from a couple of roses and some bamboo at the back. It ate the back third of the lawn, and was munching on the front third. I miss my naivity when I visited, saw a meadow of three foot high foot plants and thought "what beautiful blue flowers". And when the agent said it would be taken care of before I moved in...
Well, certainly the three foot plants were gone a month later when I moved in, but already on that day there were new 3-4 inch plants in all the beds again, and in all of the back third of the lawn, and growing in the front third. I ended up hiring someone to dig them out for 4 hours, and he said it had been allowed to be invasive for so long that the roots were over four foot, and it would keep coming back.
It stayed quiet for the best part of a month. Perhaps it was only licking its wounds before planning its next move. Then I noticed a few. Dug out/hoed out. Then a few more. Last week I noticed ones that had grown big hiding behind the bamboo. I couldn't pull them out. Dug in and the top root snapped. Last weekend, I pulled/hoed a lot of little ones from the beds.
Today (Tuesday) I pulled another 47, including distressingly a lot in the bed I had already hoed only two days earlier. I definitely had not missed them. There are also some growing in the fragile new grass that I have (incompetently) sown. I almost cried at the sight of that. And then while attempting to dig in the bed, I found a lot more of what I think are tap roots.
In case it's not clear, I am desperately in over my head here. I've bought a lot of plants that I want to put in the beds to protect the soil and - if possible - to reduce the alkanet's spread. But I don't know if it's safe to do this yet. I've googled a lot but am finding conflicting advice about how alkanets work and whether I'm following the right methods. In particular:
1) Should I keep attempting to dig out tap roots? Bearing in mind the soil is hard, and my incompetence (today I proudly dug a foot deep before the root snapped), am I actually making it worse by inadvertently leaving multiple pieces of root as has been said in one post ? Is that why they seem to be multiplying? Or am I slowly "making it better" by weakening the root, and the sudden increase is due to dormant seed?
2) Will the alkanet still come up "through" plants I put in the beds? I want to get ground cover, since it's 90% bare. But to keep on top of the alkanet, I need to hoe before they develop a tap root too hard for me to dig up. Putting plants in the beds makes that harder.
3) Is it a bad idea to plan to put bark mulch on top of the beds once the plants are in? Can that suppress alkanet? Or does it mean that by the time they push up through the mulch and I spot them, they will have generated that awful tap root?
4) Does Roundup kill the taproot itself if applied to the leafs, or will the root keep regenerating until dug up?
5) Does alkanet only clone itself by seeds, or does it spread its roots elsewhere? In other words, if I keep on top of hoeing the babies, does it matter that the tap roots remain? I keep finding a cluster of very thin brown roots when I dig but don't know whether to rip that out as well, or whether it belongs to one of the few surviving plants or previous occupants.
6) Is it okay to leave the tiniest of baby alkanets in the bed after hoeing? If it's big enough for me to identify as an alkanet, I dig it out and put it in a bag and take it away. But the beds keep growing lots of "cress like" weeds that in their first few days are hard to tell apart from alkanets. For those, I just hoe and leave them there. Could this be causing the sudden regrowth this week?
7) Should I stop spending money on plants and instead pay to have someone competent sort this out (again)? I am okay with hoeing and digging out babies. But ones that have the taproot are laughing at me.
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That is a situation just crying out to be tackled with a glyphosate weedkiller. Not now … the plants are shutting down for the winter and it needs to be applied to actively growing leaves.
… if any appear treat them as before. That should sort it and you can dig over and create a garden.
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
1. In my experience, the only thing that works is digging every bit out. And then again and again. Sorry. But it does work.
2. I have / had a few in paving or other spots where I cannot dig. On these I have used glyphosate. Repeatedly. Eventually it weakens them but is not as effective as manual removal, in my experience. However, occasionally it's the only option.
3. Don't hoe them. However small, remove them root and all. Otherwise you're making it much worse.
4. Yes, they will come up through other plants. Whether they are reduced or not I don't know, but I have had them enmeshed in the rootball of shrubs etc. Again, sorry.
Lots of sorrys. But they can be beaten, and if you get the big ones, any regrowth from the bits of root tend to be easier to remove and quite satisfying.
Mowing will help to keep it in check in a lawn, but if it spreads by rooting, it won't stop it getting into borders/beds.
Anything small that you regularly hoe will eventually [in theory] give up, but without killing the tap root, it's still possible for it to grow, like dandelions do. If you hoe new seedlings, and leave them on the surface, that part will die off.
The other little plant you describe is likely to be bittercress, and those are shallow rooted, so hoeing them will generally see them off very quickly.
I live in west central Scotland - not where that photo is...