We have a flower bed where we planted some mint a couple of years ago. The mint had taken over the bed. We have dug up most of the mint, however, it keeps returning. Any ideas how to completely get rid of it?
Poison it or pull it. They key to weeding it out is to make sure you pull new sprigs of it every day before they have had a chance to put energy back in the plant. Smothering it with some kind of mulch will work to.
If you cover it with carboard etc, that will work for the area that's been covered, but since it sends out long shoots along the ground, likely as not it will pop up somewhere off to the side. I would treat mint like quackgrass: dig through the whole area foot by foot with a digging fork (or a shovel or spade if you don't have one) and get all the roots, make really sure not to miss any. You don't have to go very deep--mint is shallow rooted--but just follow those long shallow roots wherever they go, and try not to break them because then you're leaving a fragment in the ground and it will grow.
You'll probably miss one or two bits no matter what, but then you keep an eye out over the next few weeks till leaves pop up from those, and dig them out too.
If you cant dig up any flowers (like ones that come again each year) then best thing to do is get some weed killer, cover hands ect with rubber gloves, use a paint brush/ make-up brush ect will do, hold a small clump of mint in one hand and paint the weed killer onto the mind, this will save the killer spreading by wind or spray onto plants you wish to save.
use a shallow dish or bowl and only pour in enough killer into the bowl at a time so IF there is spillage, you don't spread the killer everywhere.
I would do this in the morning (early) so there are not a load of animals around who may lick the poisonous killer or early evening, try to avoid times when there is breeze or wind that will move the plants around when wet with weed killer as this is another way to spread.
You may have to repeat this painting of killer over a whole season but by using a type that is taken down to the roots should after a few weeks show results and will be less harmful to neighbouring plants IF this method is used,
Trying to dig out the roots of mint is a thankless task as this plant regrows from broken bits of root, even a piece or root a fraction of an in will re-root and thats another new plant.
Next time you wish to grow Mint, grow it in a pot and if you wish, sink the pot into the soil, the pot prevents the mint roots from spreading under ground as all mint does, even stems being allowed to lay on top soil will take root within days, care is required with this plant,
Hope this helps you out a bit and good luck. WeeNel.