Well, I'm here to applaud dianthus as a reliable twice a year bloomer if you dead head. I got a few of a variety with a slightly grey foliage and the most intense ,hot fuchsia color blooms. Sitting slightly elevated in a 'watered only by rain' border ..full sun and even more reflected off house and driveway.
Maybe siting is important to dianthus so they don't suffer wet feet in winter. They're under a vitex tree which soaks up excess rainwater.
Still, I can't rely upon bloomtime to coordinate with other plants unless I buy all at the same time,in bloom, and sink the pots in the ground like an artificial display.

As for Columbines, over the past three years they have come into favor with home gardeners and are readily available from Lowes and Home Depot. Why wait for seed ?

plants should receive at least 4 to 5 hours of sun a soil
PH of 6.75 is ideal they need a well draining soil and do not over water and try to keep the foliage as dry as possible plants should be planted so the crown of the plant is at soil level and do not mulch they do not like it
it will keep the plants to wet.they like good air circulation at all times a 10-10-10 fertalizer is good
some of my favorite but hard to find are the following
Dianthus barbatus (sweet williams)
Dianthus gratanopoliams Firewicth a good hot pink
Dianthus Allspice 17 century plant raspberry red w.a white margin grows to 10"
Dianthus Dainty dame is smaller w/white flowers a compct plant
Dianthus Lady granville (1840's) highly scented white petals laced w.red great plants
Dianthus Sinkins (1860's) an old fashion plant w/double pure white flowers and extremely fragrant a must have
there are of course more common one that are just as good for the garden.

Blueangel

I love firewitch. It is really tough and blooms a very long time in spring - sporadically through summer if you can keep up with the deadheading. I bought a very small dianthus barbatus heart attack from PDN last spring and have been thrilled with it. PDN says this one is perennial. The flowers are a really deep red and they bloomed a pretty long time. It also grew amazingly and has been evergreen.

I live down east near Greenville NC and my Mexican Heather is blooming with very small pink flowers in this really cold weather. Linda

Columbines seem to be the signal bloomers for returning hummingbirds which arrive here in late April and early May. Some species/hybrids bloom very early but most bloom in May and last til early June.

Dianthus can be tricky but most people that can grow Rosemary or Lavendar have no problems growing it. They seem to like poor gravely soil and tend to wimp out during really hot weather. They do great planted right up against the pavement or in a rock garden. They also do well in pots. Some varieties do really well here but not all.

If you had started either of them by last fall and sheltered them through the winter you might be able to coax a few blooms out of them this early spring/summer.

I have no problem growing perennial dianthus -- however, the deer LOVE to pull it out of the ground and spit it out!

I have a wonderful edging of dianthus inside my fence along a gravel path, but the dianthus along my front path was destroyed over the last few weeks. I grow it "high and dry" like my lavender and rosemary. The foliage stays nice looking mostly year-round in my garden, with the hottest months being the hardest on the plants. I deadhead after the first bloom and get a weaker, spotty second bloom.

Dianthus gratianopolitanus 'Mountain Mist' is a favorite and more heat tolerant than some of the others.

If dianthus doesn't do what you want and you'd like a longer blooming color try ice plant. The hot pink flowers..well, I've already had some in bloom before this period of cold weather. In 'real' spring it will begin blooming and not quit until late fall.

I can second what Dottie says about ice plant. Drought tolerant, grows in poor soil, no pampering. Blooms almost continuously, spreads rapidly as a ground cover. Is evergreen, but isn't very noticeable in winter due to the low profile. Mine is a fuschia color.

Re-reading your post about red/white flowers, you might want to look at
Salvia microphylla 'Hot Lips'
sun/part sun
height 2.0 ft
width 4.0 ft
water average
growth rate average
zones 7-9a
well drained soils
red and white flowers

Flowers are red and white bicolor. With warm summer nights the flowers will be mostly red.