UPDATE 2019:

I still have the 3 plants shown in the original post but they performed for the first time really poorly ie not as many flowers and each not lasting very long. I think I could have predicted this as for the past couple of seasons but especially this season I had wild grass get "mixed in" with each clump...so intertwined that it was problematic pulling these grass stems from above ie many would snap off still leaving the root below in the clump of allium.

I am wondering what can be done to remove these grasses.

I am a bit skeptical that digging up each clump to try and pick out the individual grass stems can be successful.

Anyone else encounter the same problem?

I have Bermuda, so grass is a given, but it doesn't seem to affect the plants which do most of their early growth cycle before the warm-season grass is active. If I had to deal with it, I'd use a grass specific herbicide.
My Millenium is pretty much asking to be divided this fall or next spring. I could probably make a 10 foot row if I wanted to do something silly (which I won't) of planting one by one in a line.

Alliums die down at the end of the season. Around that time, or whenever the foliage starts to go, dig up the whole clump, separate the bulbs from what is left of the foliage, throw out the mess of old bulb foliage and gras, and replant the bulbs as if you just bought them dry from the garden centre. That should be doable, and you could even divide the bulbs into two or more clumps, if you like. As you say, pulling out grass from between actively growing bulbs doesn’t work. This should, I think.

My Millenium is pretty much asking to be divided this fall or next spring.

For all I know that may well be the issue. for me and not the grass intrusion per se.

(dbarron, how old is your millenium clump that you intend to divide?)

I think 3 years in the ground blooming, but was late summer planted, so they're probably a four year old. The pot had at least ten growing points when I planted them. More like thirty now I think.

Grass can be such a nuisance in perennial beds. It grows right through some of my bulbs like daffodils, muscari, etc between the layers of bulb as it multiplies. I can see how grass could be a problem with this allium since it isn't even bulb form but herbaceous perennial form. Have you tried giving the soil a good water, loosening the ground around the grass with a fork and seeing it they grass will budge that way? If that wont' work them then like the others above I suggest you wait till the weather is good and cool in your area and prepare to divide just in case since the grass root infestation may require that. You might try removing the whole clump with a fork first so that the grass might naturally show it's root origins, and then you could just replant the whole clump as one. If they are still tangled in, you could always try to hose off or soak off every piece of soil, therefore loosening the grass. I find this doesn't work as well as the books say in my sticky clay soil, but imagine it would work nicely in a sandy soil. I often find nasty ones like that end up in a few pieces when I finally get the rangy weed roots out, but if it's a healthy plant then better than loosing it altogether.

Just as a follow up from my post above, my little plant has beefed up quite a bit and had 5 blooming heads this year. So nice to have one that is not just a bulb, keeps its foliage and bloom after most of the bulbous types.

Millennium is sold as a perennial and AFAIK isn’t available as dry bulbs since it doesn’t form large bulbs. Growth pattern is more like chives.

Just came in from digging up and diviidng a couple of our 4 year old Millenium clumps:

Take a look:

I think they'll profit from division..looks crowded.

This is my second summer of growing allium millenium. It performed very well and last winter I left the seed heads in place for visual interest. I have several seedlings coming up around my plants. This variety is supposed to be sterile. Has anyone else experienced seedlings? I planted it because I didnt want something else to weed while I'm aging gracefully.

brightonco, all I can say is that I have had several of these allium going back probably 5 years and I have never seen any seedlings (as advertised).

I also get seedlings off my three 'Millenium' which has caused me to questioned if there are, in fact, 'MIllenium'.

I had to think where I purchased all my allium 'Millenium'. The ones I purchased from Select Seeds did not reproduce by seed. However, I saw several Millenium onion at Lowes on the discount table and couldnt believe the new perennial plant winner was on sale. I purchased four and planted them in a specific area in my backyard garden. Those are the ones that had seedlings. Buyer beware? Did I not purchase a true allium 'Milleneum'? Photo Below.

I don't believe mine produce seeds.

I have either "Blue Eddy" or "Blue Twister" -- I don't remember which, but they are a short cultivar -- and I love them! They do well in part-shade and bloom beautifully, foliage is terrific all season, though does splay a bit after flowering, which is in August and lasts for a few weeks.

Fun to let some 'Millennium' seedlings show their stuff, this one flowering a good deal later than all others, really nice color and fullness as well, a keeper!

Those flowers seem larger than "original" Millennium...nice.

"Maybe" slightly larger at most, but the color is what draws me and the fullness, here's them together. Will be fun to note if it flowers as late again next summer.

Your Milleniums look beautiful with the yellow flowers, FrozeBudd!

Mine were planted 3-4 years ago, and while I like the foliage and blooms, I find the bloom time very short. How long do yours stay purple? It feels like a little over a week in my garden.

Here, today (August 6/22)

They spread out nicely! I don’t know where to put them, otherwise…

Looking good, rouge21, they sure did fill in wonderfully!!

I like to intermingle alliums "Summer Beauty" and "Millennium", to get about two months of presence from the group.

Ahhhh, gorgeous evening !!

I purchased two gallon sized pots of allium Lavender Bubbles on clearance for $5 each yesterday. Should I divide the clumps before planting?

$5?! Wow! At that price, might you be able to pick up a few more pots?

No, I'm pretty sure I got the last alliums. The sale perennials all have browned foliage and are arranged in no apparent order but allium foliage is distinctive. There are other treasures (a 5 gallon peony Do Tell for $10 called to me because I adore that peony but I can't think of a planting site for it). It tortures me to walk away from a good deal but any plants purchased now need to be planted soon or they would take up space in my garage all winter.

I have 5 Millenium to get in the ground, along with a bunch of other bare-roots. This is still a cheap option - I am pretty sure they were less than £10 - same for hardy geraniums, geums, hemerocallis etc.

You will love them as they are bullet proof! Mine are planted in my dry slope and they dont miss a beat.

@GardenHo_MI_Z5: Love the repeat of Millenium!

Maz thank you. Here’s a closer/better view looking from opposite side...

GardenHo: Wow they really shine from that angle!!

Just a tip for deals late in the season. Buy them even if you can't plant right away. Plant the whole pot up to the rim and transplant in the spring.

GardenHo: Wow they really shine from that angle!!

So true @mazerolm_3a. Great pic @GardenHo_MI_Z5.

I do love these later blooming compact alliums (not just Millenium) and maybe its my imagination but it seems to me that Millenium, and maybe these others, dont bloom for as long as I would have expected.

@rouge21_gw (CDN Z5b/6a): I’m with you on this. I’ve debated pulling them out because of it. They fade out super fast in my garden.

Thank you for the collective wisdom of the forum. I visited a regional nursery this morning and purchased two quart sized Millenium. Dividing each gallon sized Lavender Bubbles in half yielded six alliums to plant GardenHo style with a two toned effect inspired by NancyR.

I am a fan of late-blooming alliums. These are nice--planted some last year and hope they will be happy to return next year.

“dont bloom for as long as I would have expected.”

Rouge I recall you saying this last year and I was surprised to hear it as they seemed to bloom long for me? Now with Maz agreeing, I will make it a point to watch them this year...out of curiosity alone. I have wonder if both of yours are in full sun? Mine are part shaded although by late afternoon Sun.

“six alliums to plant GardenHo style”

Lol Cecily! I hope you enjoy them much as i do : )

I have wonder if both of yours are in full sun?

@GardenHo_MI_Z5, my alliums are in full sun.

I do "complain" that they dont bloom for as long as I expected or would have wanted but I still love them in our garden. With the large grouping that I have I am mesmerized by the sound and the sight of so many bees on them when they are in full bloom.

I am a tad miffed at the pinkishness of these, having decided on a 'no pink' rule in the new garden beds. They will look completely ghastly, next to the peaches, corals and oranges of agastache , salvia and sphaeralcea. I am now thinking to plant them along one of the path edges, under a rose hedge (I used to grow a chive edging and there are always a few remainers). I have a dozen hardy geraniums, including the fairly fleetingly flowered magnificum and a handful of wallichianums, which had been destined to do the same job so I am just going to stuff them all in together and see how it looks. Mostly irritated because I don't see any chance to plant any of them for ages, having missed my window before the bulbs and primulas start to expand. Now stuck with them in pots until May/June.

I was miffed that I could not get more Allium senescens which for me is a lovely lavender. I put in A. 'Millenium' last fall and I do like it but it is very pink. I do try to keep pink to a minimum because I find that too much is simply too much for me.

@GardenHo_MI_Z5: mine are in full sun too. Maybe I will move them next year to a shadier location.

I thought of this thread as I spied our grouping today :).

Camp I was disappointed with the color initially, thinking they would be much more purple (my fave). But they obviously have grown on me...

It will be interesting Maz if you do ‘experiment with them‘ as Ken would say lol. I'm thinking the sun is a big factor...

The Fine Gardening GPOD shows a nice "Rouge style" stand of Millenium today.

Your garden really is tremendous, GardenHo! I am also a bit wary of pink, perenne, One of the very worst colour combos I ever made, concerned 3 pink roses. I had a very pale, creamy pink, a slightly darker, clear pink, and a cool lavender pink. Grief, they looked unspeakable together.

I hadn't really paid any attention to colour wheels and theory,: colour preferences seemed to be idiosyncratic, emotional, very subjective. Nonetheless, I did learn a sharp lesson regarding tonal differences (especially after going back to school for 4 years). Made me a much better gardener (I had some great teachers, and this was before the decline of our Further Education system). Not that any of this new competence was in evidence in my own gardens...

Rouge's displays always look peerless. I have never seen one looking less than lush.

Not that any of this new competence was in evidence in my own gardens...

Haven't laughed so hard in a long time.

Rouge's displays always look peerless. I have never seen one looking less than lush.

Too kind @rosaprimula UK (Cambridge) Z8/9 but I do my best to not post pics of the many crappy parts of our garden ;).

Rosa thank you!