Particularly Painless Plants: Tall Garden Phlox

Garden phlox (Phlox paniculata) is usually called “tall garden phlox” to distinguish it from creeping phlox (P. sublata) and the 65 other species in the family. It has also been repeatedly called “the backbone of the garden border.”

No wonder.

It’s typically tall – two to three feet or more – so it really can be a strong addition to the back of the bed or border. A newer range of varieties, ranging from 10 to 14 inches, is also available.

(I wonder if we should call those “short tall phlox”?)

Phlox is showy and available in a range of colors from pink to rose to bright red to lavender, purple or white. Some cultivars are prettily bi-colored with an eye in the middle of the flower one color and a contrasting color around the edges.

Phlox is also a long bloomer, one of the main requirements for being “particularly painless,” putting out a non-stop flower show for up to six weeks in mid- to late-summer. It is relatively easy to grow and is fast to establish and spread.

It’s a butterfly attractor. And some cultivars are even sweetly scented.

So, what’s not to love?

Just one thing: powdery mildew. Traditional tall phlox is, like monarda, a bit of a magnet for that annoying (but rarely fatal) fungus.

Luckily, some of the newer varieties, such as 2002 Perennial of the Year, David, have been bred to resist mildew. In any case, the problem can often be avoided by making sure the plant has plenty of air circulating around it and by refraining from getting the leaves and stems wet when watering.

Phloxes are generally sun-lovers, though they can tolerate some light shade. Paniculata varieties typically bloom in the hottest part of the summer, July and August, and some of the newer cultivars are advertised as being capable of blooming into September.

Being late-season bloomers, unless you live where it stays warm well into autumn, there isn’t much need to deadhead the plants, except to keep them neater-looking. By the time most phloxes are spent, the summer is gone.

Simple to care for

They like a fair amount of water, not surprising for plants that bloom in the hottest weather, but again, beware of letting the leaves stay wet for too long or you’ll be inviting mildew.

Propagation is simply a matter of dividing the roots and leaving the strongest three to five stems in fall or early spring. Since they’re steady spreaders, you’ll want to divide the plants every 3-4 years to keep them from getting too crowded (and thus fungus-prone.)

In summer, you can also root 3 to 4 inch stem cuttings that have no flower buds on them.

Older hybrids tend to devolve back to a pale magenta, so clean up fallen flowers to keep the plants from reseeding. Newer cultivars are often sterile, freeing you from even that small chore.

Fall care requires only that you cut the stems down to the ground (I always leave a few 6-inch stubs to remind me where it is!)

Occasionally, spider mites can be a problem but even those will rarely harm a healthy plant.

Tall garden phlox was a staple in the gardens of our grandmothers and great-grandmothers. With the improved varieties available today, they can be a very satisfying addition to almost any painless garden.

Do you have a favorite phlox that does especially well for you? Tell us all about it in the comments section below.

Phlox photos courtesy of Wikimedia Commons. Phlox Amethyst photo (top) by Epibase. Phlox Rosa Spier photo by TeunSpaans.