How to Grow Saponaria Plants

Guide to Growing Rock Soapwort and Bouncing Bet

This section is dedicated to growing perennial varieties of the Saponaria plant such as Rock Soapwort and Bouncing Bet; Click here for information on how to grow Annual species of Saponaria such as Soapwort.

Perennial Saponaria range from 15 to 90 cm (6 to 36 inches) in height. Like the annual varieties they may have pink, white or red flowers. Plants carry lance shaped leaves.

Perennial Saponaria flowers bloom from late in spring through to early summer.

Saponaria officinalis
Saponaria officinalis by Gmayfield10.

Saponaria flower close-up by Pastilletes. Both photographs under creative commons licence.

Saponaria Plant Growing and Care Guide

Common Names: Soapwort, Bouncing Bet, Cow Herb, Sweet William, Rock Soapwort, Crow Soap, Common Soapwort.
Family: Caryophyllaceae.
Life Cycle: Hardy annual. Hardy perennial.
Height: 4 to 30 inches (10 to 75 cm).
Native: Europe, Southwestern Asia.
Growing Region: Annuals: zones 2 to 10. Perennials: zones 3 to 9.

Flowers: Spring and/or summer.
Flower Details: White, red, pink. Fragrant. Five petals. Flat.
Foliage: Lanceolate. Opposite. Broad.

Sow Outside:
Annuals: Stratify seeds for one month. Surface. Following the last frost or in autumn (in warm areas). Spacing 10 inches (25 cm).
Perennials: Stratify seeds for two months. Surface. Spring (in warm areas). Spacing 16 to 18 inches (40 to 45 cm).
Sow Inside:
Annuals: Mix seeds in a growing medium, place in a freezer bag, keep moist, then stratify by refrigeration for one month. Germination time: one to three weeks in the light. Temperature 70°F (21°C). Five or six weeks before expected last frost. Transplant outdoors following the last frost.
Perennials: Stratify seeds for one week in the fridge. Sow on moist blotting paper in a covered plastic petri dish or similar. Germination time: one to three months in the light. Temperature 70°F (21°C). Once seeds have germinated transfer them into individual peat pots. Transplant outdoors following the last frost; minimum temperature should not drop below 41°F (5°C).

Requirements: Partial shade for best results; will grow in full sunlight. Soil pH 6 to 7. Wet soil. Boggy soil. Moist soil. Regular watering to keep soil wet. Do not water crowns and keep them high to prevent rot. May take up to five years for seed grown plants to flower. Propagate: dividing in the spring (cool areas) or autumn (warm areas).

How to Grow Saponaria Plants

The seeds of Rock Soapwort, Bouncing Bet and other perennial Saponaria plants should be sown on the surface. Do this in either early autumn or spring.

The spacing in which the seeds are sown is species dependent: small Saponaria should be sown about 10 cm (4 inches) apart, whilst larger varieties sown from 25 to 40 cm (10 to 16 inches) apart.

They can be grown in either sunny or lightly shaded areas, and ideally be grown in a dry and rocky soil.

They love a moist and rich soil and may grow uncontrollably; so if growing in these conditions it is important to weed them vigorously.

If starting perennial Saponaria species such as Soapwort from seed indoors, then do so about 10 weeks before due to be planted out (end of autumn or just before the last frost of spring).

Bouncing Bet seeds should be imbibed by placing the seeds (within soil) in a black bag, then placing in the fridge for three weeks. Seeds should then be sown out at a temperature of 20 Celsius (68°F) in the light; they normally take about 10 to 20 days to germinate.

Caring for Saponaria - Bouncing Bet, Soapwort

It is pretty easy to care for and maintain Perennial Saponaria plant species such as Bouncing Bet and Rock Soapwort.

In prolonged dry periods, give them a light watering. Cut back the plants once flowering has finished to keep them attractive; this may also lead to a further bloom.

If you require more Saponaria plants, then they can be propagated by division at the start of spring, or take cuttings from soft wood at the start of summer.

I hope that you enjoyed this guide on how to grow Saponaria plants. You may also enjoy the following Gardener's HQ growing guides: How to grow Irish moss and Gypsophilia plants.