Large-leaved phlox – planting, care and tips

If you are looking for a lush and colorful permanent bloomer for the summer, you will enjoy the large-leaved phlox and its varieties.

Profile of large-leaved phlox:

Scientific name: Phlox amplifolia

Plant family: phlox family (Polemoniaceae)

Other names: Largeleaf phlox

Sowing time:

Planting time: spring or autumn

Flowering period: July to September

Location: sunny

Soil quality: sandy to loamy, nutrient rich, humus rich

These information are for temperate climate!

Use in: flower beds, bouquets group, planting borders, cottage garden, flower garden, natural garden

Winter hardiness: hardy, USDA Plant Hardiness Zones: 4 (-32 °C / -25 °F)

Bee and insect friendly: Yes

Plant characteristics and classification of large-leaved phlox

Plant order, origin and occurrence of large-leaved phlox

The large-leaved phlox (Phlox amplifolia), like almost all garden-worthy phloxes, comes from North America. In the Southern Appalachians and in the highlands of Tennessee and Missouri it grows in sparse forests and on the edges of trees. The largeleaf phlox is similar to the garden phlox (Phlox paniculata), but proves to be more robust and healthier. Since it also tolerates drought well, the plant is a valuable addition to our gardens in times of climate change. Only since the beginning of this millennium have floriculturists been concerned with it in more detail and there are already a large number of new varieties. A perennial inspection is currently taking place in order to determine which species the new varieties belong to. Like all phlox, large-leaved phlox also belongs to the phlox family (Polemoniaceae).

Characteristics of large-leaved phlox


The perennial Phlox amplifolia spreads out into lush clumps with short runners, of which the sturdy stems grow upright. Sometimes the stems have red spots. The height of growth is between 90 and 120 centimeters (36 and 48 in), some varieties can reach heights of 170 centimeters (68 in) with a good supply of nutrients.


Large-leaved phlox has the largest leaves of all species in the genus, which is what it got its name. They sit opposite each other up to the tip on the stems. The broadly lanceolate leaf has a serrated edge and is finely hairy on the underside.


The five-fold, radially symmetrical single flowers always sit together in several in panicles. Phlox amplifolia proves to be a reliable permanent bloomer from July to September, constantly sprouting new inflorescences from side shoots. The color spectrum of the varieties ranges from pure white to various shades of pink with and without eyes to bluish shades.


The large-leaved phlox forms capsule fruits that contain the seeds.

Large-leaved phlox – cultivation and care


Phlox amplifolia likes a sunny spot, but can also cope well with heat and partial shade. It is particularly noteworthy that it tolerates the pressure of the roots of woody plants well.


Ideally, the large-leaved phlox should be planted in a humus-rich garden soil. Good permeability is important, which means that on heavy soils you have to ensure good drainage.

Planting large-leaved phlox

Like all perennials, large-leaved phlox is best planted in spring or autumn. A plant spacing of 50 to 60 centimeters (20 to 24 in) is recommended, two to three plants per square meter (10 sq ft.) are sufficient. A layer of mulch around the root area makes it easier for the young plants to grow and keeps the moisture in the soil.


Large-leaved phlox copes well with drought, but will be grateful if you water it at the time of budding and during flowering in prolonged periods of drought.


Annual composting in spring ensures a good supply of nutrients.


If you cut withered inflorescences from the phlox in time, you can extend the flowering time.


The large-leaved phlox should be left alone for the first five years so that it can establish itself well. The rhizome is only divided in autumn to rejuvenate when the flowering capacity has decreased.


Phlox amplifolia is best propagated by division or cuttings in spring. The extraction of root cuttings is also possible.

Diseases and pests

In contrast to garden phlox, Phlox amplifolia shows hardly any susceptibility to nematodes, powdery mildew and leaf spot diseases.


Large-leaved phlox is hardy down to-32 °C / -25 °F.

Use in the garden

The large-leaved phlox is ideal for planting on the edge of trees, where it harmonizes with trefoil, liverwort and daylily. It is also an eye-catcher on sunny open spaces or in beds and borders.


The newer varieties of Phlox amplifolia often have names that are reminiscent of the North American indigenous people.

  • ‘Minnehaha’ blooms reddish-violet
  • ‘Winnetou’ is strong dark pink
  • ‘Great Smoky Mountains’ are pale violet-blue
  • ‘Waupee’ and ‘White Cloud’ are pure white

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