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How to Grow Polygala — Milkwort

Polygala myrtifolia
Polygala myrtifolia or the myrtle-leaf milkwort flower, blooming in spring in the garden

Polygala includes perennials and shrubs that bear deep blue pea-like flowers in spring and summer. They are tender plants well-suited for warm gardens or for growing in a conservatory.

Polygala flowers have 5 sepals; the inner two form broad, petal-like “wings.” Leaves are blue-green.

There are 500 species in the Polygala genus. Two—Polygala x dalmaisiana and P. myrtifolia–are small shrubs that are prolific bloomers in summer. They make showy low hedges or border edges.

Sweet Pea Shrub, Polygala dalmaisiana
Sweet Pea Shrub, Polygala dalmaisiana

Get to Know Polygala

  • Plant type: Evergreen shrub, perennials
  • Growing zones and range: Zones 6 to 10
  • Hardiness: Leaves will drop and plant can be damaged in cold winter regions
  • Height and width: 6 inches (15cm) to 8 feet (2.4m) tall depending on the variety, 3 to 8 feet (.9-2.4m) wide
  • Foliage: Leaves can be alternate, opposite, and whorled
  • Flowers: Racemes of pea-like flowers; each flower has 5 sepal, the inner two form, broad, petal-like wings
  • Bloom time: Late spring and summer
  • Uses: Woodland, rock garden, or shrub border
  • Common name: Milkwort, Seneca, snakeroot
  • Botanical name: Polygala
  • Family name: Polygalaceae
  • Origin: Southern Europe and South Africa

Where to Plant Polygala

  • Plant Polygala in full sun or part shade.
  • Grow Polygala in humus rich, well-drained soil.
Polygala myrtifolia
Polygala myrtifolia

When to Plant Polygala

  • Plant container-grown Polygala in spring or autumn.
  • Start plants from seed in spring.

Planting and Spacing Polygala

  • Space 1 to 8 feet apart depending on the variety.

How to Water and Feed Polygala

  • Keep the soil evenly moist.
  • Fertilize Polygala with an all-purpose organic fertilizer in spring.

Polygala Care

  • Mulch around Polygala with aged compost to slow soil evaporation.

Polygala Pests and Diseases

  • Aphids and whiteflies are occasionally a problem.
Polygala calcarea
Polygala calcarea

Polygala Propagation

  • Sow seed of hardy species in containers in spring; sow seed at not less than 60°F (15°C).
  • Take softwood cuttings in early summer, or semi-ripe cuttings in mid- to late summer.

Polygala Varieties to Grow

  • Polygala calcarean: Low-growing perennial; upright spikes of deep blue flowers with a white fringe on the lip; grow 2 inches (5cm) tall and 8 inches (30cm) wide.
  • P. chamaebuxus: Perennial grows 6 inches (15cm) tall and twice as wide; clusters of yellow flowers with white lips in late spring and early summer.
  • P. x dalmaisiana, sweet pea shrub: Tender shrub with lanceolate blue-green leaves grows to 3 feet (.9m) tall and wide; purplish-red flowers in late spring and summer.
  • P. myrtifolia, myrtle-leaf milkwort: Tender shrub grows to 3 feet tall and wide; blue-green ovate leaves; greenish-white flowers veined with purple in late spring and summer.


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