Saponaria ocymoides (Rock Soapwort)

Seed Treatment 

Cold Stratification Steps:

  1. Mix seeds with moist sand, vermiculite, or a damp paper towel.
  2. Place the mixture in a sealed plastic bag.
  3. Refrigerate at 35–40°F (1–4°C) for 2–4 weeks.
  4. After stratification, sow seeds immediately indoors or directly in the garden.

When to Sow

  • Indoors: Start seeds 6–8 weeks before the last frost.
  • Outdoors: Sow in early spring after the last frost or in late fall for natural stratification.

Soil Requirements

  • Prefers well-draining, sandy or gravelly soil.
  • Tolerates poor and rocky soil conditions.
  • Ideal pH: 6.0–7.5.

Light Requirements

  • Thrives in full sun.
  • Can tolerate light shade, but flowering may be reduced.

Sowing Depth

  • Sow seeds ⅛ inch (3 mm) deep or lightly press onto the soil surface.
  • Do not bury deeply, as light aids germination.

Watering

  • Keep soil evenly moist but not soggy during germination.
  • Once established, it is drought-tolerant and requires minimal watering.

Germination Time

  • Germinates in 10–21 days at 65–70°F (18–21°C).

Spacing

  • Thin or transplant seedlings to 12–18 inches (30–45 cm) apart.

Growing Tips

  • Saponaria ocymoides forms a low-growing, trailing mat of pink flowers perfect for rock gardens, edging, retaining walls, and ground cover.
  • Blooms in late spring to early summer.
  • Cut back after flowering to maintain shape and encourage denser growth.
  • Very hardy and tolerant of neglect once established. Deer resistant and attractive to pollinators.