PlantFiles: Mountain Cornflower, Mountain Bluet, Perennial Cornflower
Centaurea montana

I have had this plant for several years but did not know what it was until now. This plant is growing in poor clay soil on the west side at the bottom of my deck steps in full sun. I have nepeta growing by it and a red and pink honeysuckle vine. The color of the perennial cornflower is outstanding. It does reseed in mid summer, but I just pull them up.

Hi! This plant has very pritty, true-blue flowers. This will be my third year growing it; I am very happy with it. The plant was quite small when I bought it, but it has now formed a nice clump, which I may be able to divide this spring. Mine is in a somewhat droughty area, which may be the reason it has not re-seeded everywhere.

Love it. Planted it 3 days ago & already blooming beautifully. It calls for full sun but I am reading it does well in partial. I recently joined this site to learn more, given my novice gardening skills. My mountain blue is covered in RED ants, which I am now relieved to find is normal.

The blooms are electric blue! It really reseeds, but is easy to control by pulling. It doesn't need watering or any special care. I've had it grow in sun and shade.

So far this has not been invasive for me. I have moved it several times trying to get it in just the "right spot," so it may not have had a chance. As long as it stays well behaved, I really like it. Another name for it is Perennial Bachelor Button.

I must agree with haighr, this plant is very invasive in my yard. Thankfully it is in a bed separated from most of my other plants. It spreads with abandon and has roots that seem to go on forever. If I can ever get rid of it I would never bring it back in to my yard again. I do not even offer it as a freebie to my friends.

This is one of the weediest pretty flowers I have ever seen. I moved into a house that already had these established and I think it is the house I live in that has been the epicenter for this plants spread throughout the neighborhood.
Plants look great while young and in flower... once the flower is done and gone the plant looks rugged and weedy. The plant spreads by offsets produced at the base and very well by seed. They are a pain to uproot.

A good hair cut is what this plant needs to keep looking good in MN.

Invasive or just ruggedly robust? We prefer to say the later.

This plant has been hardy here in zone 4, and hasn't been invasive for me at all. Actually, I would have given it a positive except that it gets kinda weedy looking in late summer. I'll try cutting it down like someone suggested.

I also loved this plant and tried one. It gave me quite a show of flowers. About June 23 (Holland, PA, zone 6) I noticed something that another subscriber also mentioned. It appeared that the plant was choking and that a cat laid down in the center of the plant and parted it to the left and right. I watered it well but it remained wilted looking. I always deadheaded the plant so I knew it was nothing I purposefully did not do. I decided to cut it down to about an inch in the hopes that the plant will revive itself. I also left the flowers that I deadheaded around the plant, hoping it would reseed itself. I love this plant. It shows beautiful in the sunshine and looks like a sparkler on a birthday cake when it blooms. Any other info on this plant, and also on the yellow variety would be appreciated. Jan D.

I love this plant so much I moved it from Vancouver BC (Zone7) to Kimberley BC (Zone3) with no problems. I've never had a problem with it getting out of control 'cause as soon as it gets leggy, it is cut right back to the ground and comes back a second time, just like my 'Johnson's Blue' perennial Geraniums. I'm now trying seeds, from a friend who grows Centaurea macrocephala (Yellow Coneflower)with great success in Zone3.

My garden center identified this plant as a bachelor button. I planted three in a border in full sun and two did very well.

Very nice. Blooms in spring and still is now (late July). When coming up in the spring, it looks very fresh & lush and comes up fast. After blooming for a while the foliage begins to look gnarly and it is often covered with powdery mildew. You just cut it right back down to the ground and it starts all over again. They bloom in the fall too, even in the snow. Very popular plant in my neighbourhood but not all of them know about cutting it back a few times. I like it so much I have just bought some seeds for the yellow kind, hoping it behaves the same way.

Sandy

My perennial cornflower (just id'd thanks to the database) was a 4 inch potted plant that I got either free or for 25 cents at a closeout sale. It's planted in partial shade, made a big clump that bloomed and then fell outward like the cat might have layed down right in the middle. I cut off everything that was flat and it came up from the center and it is a nice plant again, blooming for the 2nd time this season, late July now. Mine has ants too.

I found this plant this year in my new homes garden and love it. The color show is gorgeous and does well in my zone 6 shaded area. Started blooming in early May and is just starting to give up in mid-June. A must have.

Perennial garden staple here in z5. Not invasive in my garden, stays in nice clump with iris blooming around it. The cornflower blue blooms are an excellent complement.

I have found these to be the most invasive plants in my gardens. My personal distaste is that the foilage is weedy looking to me. They are not a plant you can just reach down and pull as they root quite deeply. Although the blue flower is attractive, I find the rest of the plant unappealing.

I started with 2 seedlings from a friend, about 3 years ago. I now have almost a dozen. However, they were in a partial shaded place for 1 year and became quite mouldy and I lost a few. Moving them back to full sun this year has resulted in more blooms and more plants. Self seeding, and require deadheading for more blooms. (Zone 6b, summers seldom above 90 degrees F.)

what a show this multi shades of whispery blue flower puts on in june. with deadheading it will bloom these 2" flowers all summer long. i planted 3, 4" potted plants, 12 inches apart, may 2001. 1 plant prospered that year to bloom, 1 died and 1 hung on for life. spring 2002, with 2 plants now the one hanging on to life grew 2 leaves, then died. The final plant thrived to be ~ 20" tall and 30" wide and has stayed that size now for 2 months. planted at the border of my driveway garden, only 12 inches from the blacktop surface, in full sun it withstands the heat nicely for me. As naturepatch said they must require ants to blossom because they are covered in small black ants. So it is not a plant i cut and bring into the house.
I know this plant as a perennial Bachelor Button.

Stunning plant when in bloom. Tends to get a bit wilty in high heat, so provide shade. Attracts earthworms. Will self-seed occasionally. Deadheading will prolong bloom time. Might need ants to open like a peony. Ants are always on it when it is getting ready to bloom.