Those are couch grass roots. An absolute pain in the garden, especially when it gets into the root ball of a perennial plant. I would buy some weedkiller containing glyphosate or do as I do, find a farm shop which supplies farmers and buy neat glyphosate. Using protective gloves mix up a measure of the weedkiller and mix with enough wallpaper paste to make a thick gloop. Sort out as much of the grass shoots as you can, tie them in small bundles easing them away from your dierama, put a piece of plastic or cardboard between the foliage of the plant and the weed and work the gloop into the blades of grass. It can take about 3 weeks for the grass to die. You will need to do this continuously until the last of the weed is killed off, no reason to only treat one bundle at a time.
The only other alternative I can suggest is to lift the dierama in the Spring and separate the bulbs from the grass. You will need to remove every blade of grass and every piece of root as couch grass will regrow from any tiny piece of root. I personally would wash the bulbs to remove all soil to avoid carrying any grass seeds and plant in a new location.
Def not couch grass as that has a slightly velvety feel and the blades are narrower at the base. The image above is exactly what my little problem looks like and it grows up to 3 feet tall. It also regrows from bits of tuber so I may have to empty the border.
(Joyce) I've been chemical free for a decade or two now so would prefer to not use any, if at all possible. Appears mowing short stimulates it - which amused me as I've not mown for weeks. Nice to know what it is though.
I have a similar problem with another grass, no idea what it is called. It grows from bulbils , looks vaguely like a miniature bamboo and it smothers anything within a couple of feet from where it is growing. It makes large clumps, achieving around 4ft in height and comes in from the uncultivated fields surrounding my garden. The juvenile bulbils are miniscule, like pills of soil so is really difficult to eradicate. Similar to celandine, another pet hate of mine.
The Nutsedge isn't technically a grass so I only found the info / pictures when I adjusted my search to be on "rhizomes weed 3 foot high" and then it popped up. Perhaps if you search on rhizomes or bulbils you might be able to find yours?
Anything with a flower on I tend to tolerate - have a large clump of Speedwell, in a corner of the lawn, that has grown huge this year. I just leave it be and mow it down at the end of summer as smaller pollinators love it - and it is pretty in May. I've yet to take a photo that does it real justice.
We have a house where there used to be a huge pond and the whole garden is infested with a tall sharp edged grass that grows everywhere! We have finally given in and covered everything but the patio in thick black plastic in a desperate attempt to eradicate it! It gets between the slabs on the patio but at least there we can control it.
I've removed a lot of rhizomes/plants from the border but (at the moment) am limited where it's growing through my Dierama and Geranium etc. I've therefore pulled out the leaves (the snap at the base anyway) as the link below confirms it will deplete the energy reserves in the tuber. http://ipm.ucanr.edu/PMG/PESTNOTES/pn7432.html - in case anyone else has this issue.
Need to read some more about the lawn as it says grass will normally, if not cut too short, out compete the sedge. Whether I risk waiting for that to happen (not wanting to use chemicals) is a decision for another day. Will ask a local gardener mate what he thinks.
Posts
Those are couch grass roots. An absolute pain in the garden, especially when it gets into the root ball of a perennial plant. I would buy some weedkiller containing glyphosate or do as I do, find a farm shop which supplies farmers and buy neat glyphosate. Using protective gloves mix up a measure of the weedkiller and mix with enough wallpaper paste to make a thick gloop. Sort out as much of the grass shoots as you can, tie them in small bundles easing them away from your dierama, put a piece of plastic or cardboard between the foliage of the plant and the weed and work the gloop into the blades of grass. It can take about 3 weeks for the grass to die. You will need to do this continuously until the last of the weed is killed off, no reason to only treat one bundle at a time.
The only other alternative I can suggest is to lift the dierama in the Spring and separate the bulbs from the grass. You will need to remove every blade of grass and every piece of root as couch grass will regrow from any tiny piece of root. I personally would wash the bulbs to remove all soil to avoid carrying any grass seeds and plant in a new location.
Good luck.
Def not couch grass as that has a slightly velvety feel and the blades are narrower at the base. The image above is exactly what my little problem looks like and it grows up to 3 feet tall. It also regrows from bits of tuber so I may have to empty the border.
(Joyce) I've been chemical free for a decade or two now so would prefer to not use any, if at all possible. Appears mowing short stimulates it - which amused me as I've not mown for weeks.
Sorry!
I have a similar problem with another grass, no idea what it is called. It grows from bulbils , looks vaguely like a miniature bamboo and it smothers anything within a couple of feet from where it is growing. It makes large clumps, achieving around 4ft in height and comes in from the uncultivated fields surrounding my garden. The juvenile bulbils are miniscule, like pills of soil so is really difficult to eradicate. Similar to celandine, another pet hate of mine.
Anything with a flower on I tend to tolerate - have a large clump of Speedwell, in a corner of the lawn, that has grown huge this year. I just leave it be and mow it down at the end of summer as smaller pollinators love it - and it is pretty in May. I've yet to take a photo that does it real justice.
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7432.html - in case anyone else has this issue.
Need to read some more about the lawn as it says grass will normally, if not cut too short, out compete the sedge. Whether I risk waiting for that to happen (not wanting to use chemicals) is a decision for another day. Will ask a local gardener mate what he thinks.