Tall garden phlox (Phlox paniculata) grows in upright clumps and has long been a popular perennial for the landscape. Not only is it beautiful, but it helps you keep your yard colorful in the second half of the summer after the flowers of many other plants have gone by. A long-blooming perennial, once it comes into flower, you can be assured of color in the yard until the frosts of fall arrive.
Tall garden phlox is available in a number of different varieties. In fact, there is something to please almost every gardener, including the following:
- Flowers in many different colors.
- Plants with compact growth habits.
- Varieties with leaves that bear two colors.
- Plants that are mildew-resistant. This quality can lower the amount of care that you must put into growing them, thereby helping reduce your landscape maintenance needs.
Volcano Ruby and Nora Leigh will serve as examples of varieties of tall garden phlox. Each has its own distinct beauty. So let's take a close look at the features of these two, plus how to grow them. You will then be introduced to several other kinds, as well as how best to use these perennials in your yard.
Volcano Ruby Tall Garden Phlox
Plant taxonomy classifies this flower as Phlox paniculata 'Barthirtyone.' But the cultivar name, 'Barthirtyone' is seldom used. The flower is more often referred to by the catchier names, "Ruby" or "Volcano Ruby" (it is part of the Volcano series).
Tall garden phlox is categorized as an herbaceous perennial flower.
This type of tall garden phlox can grow to a height of 24 to 36 inches (the more shade it gets, the leggier it will become, plus it will not produce as many flowers), with a spread of about 20 inches. It grows in clumps and its leaves are lance-shaped. The name, "Ruby" is meant to suggest its flower color, but its fragrant flowers have less red in them than that name suggests. It would be a bit more accurate to group them with the purple flowers than with the red flowers, although they are not deep enough to be a true purple, either. The most accurate description of the color would be purple-magenta. Nonetheless, the clusters of flowers are quite striking. Bloom time is from mid-summer until early fall.
Its color is certainly one of the finest features of this garden phlox, and it is a feature that you get plenty of since the plant bears many flowers per square inch. Volcano Ruby is a moderately compact type of garden phlox: The very tallest kinds can grow to be 4 feet tall. Even more compact varieties will be listed later. Like other plants in the species, Volcano Ruby offers a long blooming period, from mid-summer to early fall. And its superior mildew resistance allows for its use in relatively hot climates, which is a major selling point.
Planting and Growing Requirements
Native to North America, tall garden phlox can often be grown in USDA planting zones 3 to 8. But Volcano Ruby is not quite that cold-hardy. It is listed as being hardy only to zone 4. But its mildew-resistant trait means it can be grown further south than some other varieties can (to zone 10).
This tall garden phlox is best grown in full to partial sun (in the North) and should be planted in a well-drained, loamy soil enriched with compost. At the southern end of its range, it will require more shade.
Nora Leigh Tall Garden Phlox
Plant taxonomy classifies this type of garden phlox as Phlox paniculata 'Nora Leigh.' The cultivar name, 'Nora Leigh' is commonly misspelled as 'Norah Leigh.' Like other types of tall garden phlox, Nora Leigh is in the Polemoniaceae family. The name of that family may ring a bell. This is because it sounds like Polemonium, a genus in the family that is better known by the common name, "Jacob's ladder."
Nora Leigh produces clusters of flowers that are deep-pink in the middle, with light-pink edges. The flowers are considered fragrant by many. This particular tall garden phlox may be more highly valued, however, for its bicolored, lance-shaped foliage. The leaves have light green centers and creamy white edges. The plant grows in clumps, to a height of 24 to 36 inches, with a width about half that.
The overall impression created by the light-pink edges of its flowers and its light-colored leaves is one of brightness: It is dazzling in the way 'Wolf Eyes' dogwood is, but with more color and on a smaller scale.
Planting and Growing Requirements
Nora Leigh is listed as being suited to USDA plant hardiness zones 4 to 8. It requires the same growing conditions as Volcano Ruby in terms of sun and soil needs.
Since it is susceptible to powdery mildew (like all types of tall garden phlox are, to some degree), provide adequate air circulation. For the same reason, avoid overhead watering: Moisture on leaves invites fungus (powdery mildew being a fungal disease). Nora Leigh is fairly resistant to powdery mildew, but that is no reason to chance it.
If you live where powdery mildew is a big problem (as it is in the American Southeast) and you want to avoid planting anything that tends to be affected by this disease, try P. maculata (zones 3 to 8). It is similar to P. paniculata but has less of a problem with powdery mildew. Its common name is "meadow phlox." Since it is similar to P. paniculata, an example of it will be discussed later.
Water your tall garden phlox well during periods of high heat. Apply a garden mulch to help the soil retain water.
Care for Tall Garden Phlox
To prolong its blooming period and stop it from reseeding (unless that is what you want), deadhead tall garden phlox. Even if the idea of letting the plant spread by reseeding sounds good to you, remember that reseeding can cause overcrowding, which promotes powdery mildew. Also, seeds of hybrid cultivars typically revert to one of the parents, so the new plants will not necessarily look like the phlox they came from. Dividing can breathe new life into these perennials when their performance begins to go downhill. Water the plants during periods of drought. You may need to stake the plants if they become especially tall and if they are exposed to high winds.
Other Varieties of Tall Garden Phlox
Some other types of colorful tall garden phlox flowers (P. paniculata) that you should consider adding to your garden are:
- 'Red Magic' (24 to 36 inches tall, 18 to 24 inches wide).
- 'Orange Perfection' (30 to 36 inches tall, 18 to 24 inches wide).
- 'David' phlox (3 to 4 feet in height, spreading about 2 to 3 feet).
- 'Delilah' (32 to 36 inches tall, 30 inches wide).
- 'Opening Act Blush' (18 to 20 inches tall and wide).
Like Volcano Ruby, 'Red Magic' is not even close to being a true red color. Instead, its flowers are similar in color to those of Volcano Ruby. The name, 'Orange Perfection' stays truer to what the flowers on the plant actually look like. Although their color is pink, a generous amount of orange is mixed in. As a result, this perennial has a perfectly cheerful look. 'David' has white flowers and, like Volcano Ruby and Nora Leigh, is one of the more mildew-resistant varieties of tall garden phlox. 'Delilah' bears purplish blooms, while those on 'Opening Act Blush' are a lavender-pink color.
All of these plants (as well as the plants discussed in the rest of the article, except where otherwise noted) have the following qualities:
- They are suited to USDA zones 4 to 8.
- They should be grown in full sun to partial sun (in the North) and in well-drained soil.
- They have average water needs.
- They bloom in mid-summer or late summer (depending on where you live).
Varieties With Light-Pink Flowers
Pink is a popular flower color for tall garden phlox. Some come in a deep pink color, others in a light-pink color. Examples of the latter, in addition to 'Opening Act Blush,' include those in the list below:
- 'Rosa Pastell'
- 'Bright Eyes'
- 'Thai Pink Jade'
Rosa Pastell becomes 2 to 3 feet high when mature, with a spread of 1 to 2 feet. As with most kinds of tall garden phlox, the center or "eye" of the flower is a different color from the rest of the petal. Bright Eyes reaches 1.5 to 2 feet in height and spreads to be 1 to 1.5 feet wide. Thai Pink Jade grows to be 2 to 3 feet tall, with a spread of 15 to 24 inches.
Varieties With Deep-Pink Flowers
Pick from the following for a tall garden phlox with flowers in a richer, deeper pink color:
- Pink Flame or Flame Pink (the actual cultivar name is 'Bartwelve')
Alexandra has a height of 2 to 3 feet, with a width of 18 to 24 inches. Flame Pink is sometimes confusingly called "Pink Flame." It is more compact than many kinds of tall garden phlox, reaching a height of just 15 to 18 inches, with a spread of 12 to 14 inches. Cleopatra may be the most colorful of the lot, bearing a cherry color under ideal conditions. You can also grow it one zone higher (zone 3) and one zone lower (deep pink 9) than some of the other varieties of tall garden phlox covered in this article.
Varieties With Light, Bicolored Flowers
Some types of tall garden phlox plants have bicolored flowers. Again, these can be divided into two groups: those that come in light colors and those that come in deep colors. The example used here for a light-colored kind is actually a type of P. maculata (as opposed to P. paniculata): 'Natascha.' deep pink would be a good selection for you to grow if you have problems in your yard with powdery mildew since P. maculata varieties have less trouble with mildew.
Natascha (also sometimes spelled "Natasha") grows to be 1.5 to 2 feet tall, with a width of 1 to 1.5 feet. The flowers bloom in cone-shaped clusters. The inner part of the petal is lavender-pink, while the edges are white.
Varieties With Deep, Bicolored Flowers
'Little Boy' could be said to be the opposite of 'Natascha,' in the sense that its darker color is on the edges, rather than in the middle of the petals. True to its name, Little Boy is the smaller of the two perennials. This dwarf has a mature height of just 1 to 1.5 feet, with a mature spread of only a foot (or even less than that).
There are two drawbacks to growing this plant:
- The color is not very consistent. The flower can end up a very different color from the one advertised depending on growing conditions, etc.
- It is not a very mildew-resistant variety.
Uses for Tall Garden Phlox
The various types of tall garden phlox are used in a number of different ways, both in and out of your landscaping. For example:
- Mass them together in a border planting, such as along a driveway or walkway. The border planting can consist wholly of tall garden phlox or be a mixture. Good companion plants are other sun-loving perennials that bloom in late summer, such as black-eyed Susans (Rudbeckia).
- Add them to a pollinator garden, as hummingbirds, butterflies, and bees adore phlox.
- Grow them in English cottage gardens.
- Place them in either the middle row or back row of a mixed perennial bed, depending upon their height and the heights of the companion plants.
- Use them as cut flowers.
- Plant them near veggie gardens to attract pollinators that boost harvests.
Yard and Garden: Handling and Caring for Garden Phlox. Iowa State University Extension and Outreach
A Comparative Study of Phlox paniculata Cultivars. Chicago Botanic Garden
Cox, Jeff. Perennial All Stars: the 150 Best Perennials For Great-Looking, Trouble-Free Gardens. Rodale Press, 2002