No summer flower display is complete without garden phlox, a workhorse of the home flowerbed since European naturalists first discovered our native species, Phlox paniculata. The name ‘phlox’ comes from the Greek for flame, and you can see why– there’s nothing shy about these stalwart mainstays.
Tall phlox not only put on a colorful show, they’re usually long-lived once established. Some are wonderfully fragrant. New introductions are more disease resistant than ever, and many repeat bloom, or just keep going like the Energizer Bunny.
In my quest to identify some of the best phlox choices for zone 6, I delved deeply into two exhaustive phlox trials, as well as drew on my own experience with some of the cultivars.
Let’s take a look at the top performers, new introductions and what makes tall phlox so desirable in the garden.
First, a little background.
While there are sixty-some species of phlox worldwide, most modern plants descend primarily from P. paniculata, a species native to the eastern US and Canada. From these, Dutch and American growers are breeding more compact hybrids with longer bloom periods in richer colors, such as the Fashionably Early series from Walters Gardens and Garden Girls from Proven Winners.
We call these upright cultivars “tall garden phlox” to distinguish them from creeping, woodland, and moss phlox. There are annual and biennial phlox too, rarely available except as seeds. To avoid confusion, I’m focusing on perennial tall garden phlox and their hybrids only.
Why Phlox? Color! Fragrance! Cut flowers!
Tall phlox start blooming in early summer, when the main flush of spring perennials are finishing. Many go on flowering all season. Some start in late summer and bloom well into fall. If you’re looking to add late season color, phlox are an excellent choice.
The native cultivars, or nativars, are truly tall (4 to 5 feet) but lots of cultivars are much shorter, ranging from 18″ to 3 feet. Their moderate height makes them easy to position in the middle of beds and borders, in meadows, even massed on their own. They do take a little care, but they will repay you with fabulous color all summer long.
Pros
- Long blooming, summer through fall
- Wide range of colors
- Often fragrant
- Good companion plant
- Range of heights from 15″ to 5 feet
- New introductions are mildew-resistant
- Excellent cut flower
Cons
- Susceptible to powdery mildew
- Susceptible to spider mites if heat-stressed
- Can be slow to establish
- Need supplemental watering and moderate care
- Vulnerable to deer and rabbit browse
Best Choices for the Mid-Atlantic and Northeast
In 2018, Delaware-based Mt. Cuba Center published a 3-year trial of 94 phlox selections. I also looked at an older, Chicago Botanic Garden 78-cultivar trial. Of the two, I consider Mt. Cuba’s climate to be closer to southeastern Pennsylvania’s, and their criteria were more rigorous.
Only two cultivars received five-star ratings in both trials: Jeana and Shortwood. Both are over 48″ tall; Jeana is a native cultivar discovered in Tennessee. Shortwood is an intentional cross between two well-regarded cultivars, David and Eva Cullum.
Here are ten top-rated selections and seven runners up:
Five Stars, both trials
- Jeana – A tall pink native; unfortunately no scent.
- Shortwood – Light pink with a rich pink eye. Sweetly fragrant.
Photo credits: John Henry Co. and Bluestone Perennials, respectively
Top-Rated by Mt. Cuba
- Glamour Girl (hot, saturated coral)
- Delta Snow (cool white with lavender eye)
- Baby Face (warm pink with a cherry eye)
- Lavelle (white with pale pink tubes — may be hard to find)
- Robert Poore (cool magenta)
- Dick Weaver (bright magenta)
- David (pure white)
- Coral Creme Drop (salmon-coral)
4-stars — Good performance under typical conditions:
- Blue Paradise (magenta-blue)
- Coral Flame (cherry coral)
- Ice Cap (pure white)
- Laura (lavender-purple with a white eye)
- Frosted Elegance (variegated foliage; lavender with dark eye)
- Katherine (soft lavender with a white starburst)
- Peppermint Twist (hot pink with white stripes)
photos: off the web
Of course, new introductions are coming to market all the time. The Flame series offers rich, vivid colors on shorter plants. Earlier blooming series include Early Start and Opening Act, along with Fashionably Early. Glamour Girl is a top-rated selection from Proven Winners’ Garden Girls series.
I grow some of these, but I also have others which do well for me. All took their sweet time establishing, though.
Tall phlox in my garden
Blue Paradise – An absolutely gorgeous blue-magenta that changes color with the light. Caveats: Hard to establish, needs staking when young, and must be netted for deer protection. But patience pays off!
Bright Eyes – Rounded pink florets with a deep pink eye. Extremely long bloom period, right up until frost. Always fresh looking and a vigorous grower. Flower heads are very full.
Minnie Pearl – A short white hybrid. Always the first to bloom in spring. It will repeat bloom if lightly deadheaded — cut just beneath the spent blooms — any lower, and it won’t flower again. The foliage is a dense mass of narrow leaves, which slowly spreads outward from the rhizomes. Excellent disease resistance; stays tidy and never flops.
Fashionably Early Princess – A compact lavender-pink hybrid from the Fashionably Early series. Extremely long prolific flowering period that just doesn’t quit. Again, deadhead only the spent tops. Very fragrant. Excellent mildew resistance; narrow foliage spreads slowly outward. Medium height, about 24″. Hardy and reliable.
Starry Skies – Creamy pinwheel florets streaked with lilac that appear magenta in strong sun and lilac-blue at dusk. A beautiful cultivar. May need staking, the blooms get heavy in rain.
Blue Spot -So close to Starry Skies it’s hard to tell them apart. The splashy blue florets have a white starburst effect around the eye. A bit finicky; keep an eye on it and make sure it gets enough water.
David – (5-star rated). A tall, pure white cultivar with healthy foliage and conical flower heads. In my garden, the deer browse on it just as it buds up, usually multiple times. As a result it is unable to bloom until quite late, but it’s exceptionally lovely when it does. Very vigorous.
Delta Snow – Dainty florets are white with a lavender eye and tube. Blooms July to October. Excellent mildew resistance. Tall with good branched form; tolerates hot weather well. This cultivar is a workhorse bloomer that just plows right through the hottest weather without a break. Lovely, tough, prolific. I can see why it’s rated a top performer!
Nicky — A neon deep purple-pink that’s so saturated it almost hurts your eyes. Pow! It’s all about color with this cultivar. Great for the hot garden or for enlivening paler companions. A strong bloomer with vigorous growth and good disease resistance.
Laura – Cool lavender with a white starburst at the eye. New to my garden last year, it is just getting established. It flowered very modestly. UPDATE — Laura changed color its second year from cool lavender to a screaming hot pink, evidently a result of cross-pollination. Disappointing.
Coral Creme Drop – Prolific, flowering repeatedly right to frost. Medium height; tolerates part shade. Dark calyxes and purple stems add to its allure. I didn’t expect to like this one so much, but I do! (So do the deer, by the way.)
Another coral is Glamour Girl, which is easier to find but a more saturated coral color and significantly shorter. Coral Flame is a dwarf similar to Glamour Girl but more cherry in color. Of the three, Coral Creme Drop has the best coloring in my opinion, because it blends with other colors instead of fighting with them.
Of course, there are many excellent cultivars on the market. I’m not a fan of overly saturated colors (except Nicky) but if you are, there’s plenty to choose from, including some striking reds.
Not Recommended
Here are two cultivars which proved difficult for me. If you choose to grow them, be prepared to give them some extra TLC.
Franz Schubert – A gorgeous lavender-blue phlox, this cultivar is extremely susceptible to mildew. I grew it well for a short time at my previous property (where this photo was taken) but it soon succumbed to severe disease. In hindsight, I didn’t pay attention until it was too late. If I were to grow it again, I would thin out some stems early on and treat it proactively with copper fungicide or baking soda (see TIP).
Old Cellarhole – A tall medium pink cultivar of uncertain parentage. Despite this being an heirloom variety, mine became stressed beyond its comfort zone and died the second year before fully establishing.
Growing Phlox
I’ll be the first to admit it; phlox aren’t the easiest flowers to grow. Plugs and small pots take at least two years to establish, and another year to reach full maturity. If you want to enjoy your phlox right away, opt for well-developed specimens from your local nursery. They should transplant fine with attentive watering and mulch. Many newer hybrids are quite disease resistant, too.
Tall phlox need full sun, rich fertile soil, lots of moisture and excellent air circulation. Ensure they aren’t crowded. Phlox benefit from spring fertilization, mulching and deadheading. Cultivars with variegated foliage should have some light afternoon shade to prevent leaf scorch.
All phlox appreciate supplemental watering but not from overhead, especially if mildew is an issue late in the season. (Water spreads mildew but doesn’t necessarily cause it.) Varieties with heavy racemes may need staking, as hard rains will break the stems or cause flopping. After frost, cut them to the ground and carefully remove and dispose of all dead plant material.
Dealing with Pests and Disease
Heat, drought, excessive rain and high humidity put stress on phlox, which can weaken their resistance to powdery mildew and spider mites.
To help prevent mildew, thin out closely packed stems (about a third) early in the season. Spray regularly with a copper fungicide designed to prevent powdery mildew, or make your own concoction — see TIP.
TIP! Make Your Own Fungicide. Mix 1 tablespoon of baking soda with a gallon of water and 1/2 teaspoon liquid soap, preferably an eco-friendly choice like Seventh Generation or Mrs. Meyers. Put into a clean spray bottle and shake well. Spray the whole plant, including undersides of the leaves, at least once a week during the growing season.
To check for mites, look for heavily stippled leaves and faint webbing on the leaf undersides. Treat with insecticidal soap according to package directions. To be effective, you have to wet the leaf undersides thoroughly, which is a time-consuming process. Luckily it seems to work. I’ve found insecticidal soap to be quite effective against many insect infestations when applied correctly.
Fortunately, neither mildew nor mites overwinter well if you practice good garden hygiene and take proactive steps to fight them. I’ve been growing phlox for years and while I’ve experienced most every pest and disease they get, most phlox will survive all but the worst calamities. They are still worth it in my opinion. I wouldn’t be without them!
I hope I’ve convinced you to try phlox. If you’re concerned about maintenance, start out modestly with just a few plants and see how it goes. I’m betting their lovely presence and sweet fragrance will have you at first flush.
Don’t forget to cut some for the house to enjoy! To me, phlox are simply summer in a vase.
