In my zone 5 Iowa garden they definitely work as spring/early summer bloomers. I don't get good flowering throughout the summer. The ones that are reblooming currently look pretty pathetic now that I've gone to take a good look. I made several bouquets for an event in early July and already I had no sweet Williams suitable for cutting. I imagine there are ways to manipulate bloom times. I think there are some that bloom first year from seed so maybe those would flower during the summer if started from seed in the spring. Or maybe it depends in the amount if heat? Campanula, do your summers stay pretty mild? Here's a single plant I deadheaded and it is now just a pleasant bit of glossy green foliage. This is a full sun garden but the sweet will is shaded by other plants. I've noticed some just die out by now. As grdenweed mentioned above, they are generally biennial or short lived perennials. They are one of my all time favorites. The fragrance is one of the best flower scents, IMO. I find some fragrances overwhelming, but not sweet William. I have never grown the carnation (d. caryophyllus mentioned) as I thought they were fussy. Hmmm...I will have to revisit them! :) I saved seeds from a low growing pink one as Sammy mentioned. I am hoping the offspring will resemble those plants. One can buy single color varieties from a place like Geoseed. For example, they have 11 colors of the Barbarini series available, single color packets, or mix, $3.30 for a packet if 100 seeds. Swallowtail seeds also has two red varieties for sale. If you like buying open pollinated seeds though, I think you are more likely to end up with mixes. This post was edited by trovesoftrilliums on Thu, Aug 1, 13 at 12:10

Melissa, Sweet Williams generally will not bloom in their first year. Depending upon where they are and how your winters are, they might not even "die" off completely--I think mine were green all winter, but I would put the pot under the dripping gutter if it was really dry (note to self: do NOT leave it there if there is a downpour...), and are getting ready to burst into bloom. I'm not sure of the variety, and blooming habits may be different from one to the next, but mine typically bloom all season. For the record, they will be nice green, but you should probably add some color where you are planting these. They will come up and have a bit different leaf next year. I think I unintentionally sowed about a million Sweet Williams last year, and at least half of them are coming up... Either SW, or petunias; I'm not sure which yet! I'm leaning towards petunias; either way, I'll know in a couple weeks and will be able to intersperse if it's all SW with some INTENTIONALLY WS petunias! Expect color next year (sorry!).

Trudi is right, although I've seen some so called biennials last for quite a few years. What started me on Sweet Williams was one such plant which was on it's 5th year. This was at a nursery where the gardens were tended by one of the kindest gardeners I've ever met. He looked as though he was in his eighties and noticed my curiosity about a particular flowering plant. He told me he loved the colour - a beautiful velvet wine red laced with a tinge of white - and had never let it seed in five years as he had been unable to grow another like it. The footing had grown to 1 foot in diameter and the plant was a knock-out!! I've decided to try what he did and this year I separated all the seedlings - no hunks - for about 15 plants. We have SWs in my daughter's garden which have been there for 4 years. They have to be the same plants as we've never let them seed. Now I just want to separate one colour from another.

merricat, I haven't grown columbines since we moved to our new home. I had many varieties at the old place, but somehow my seeds got lost or misplaced during the move. I planted a couple of foxgloves the first year we moved but they didn't survive, nor did they produce any seeds or seedlings. I'm looking forward to seeing your list.