How to Grow Annual Saponaria Plants

Guide to Growing Soapwort and Cow Herb

Members of the Saponaria plant genus can be grown either as annuals or perennials, this section is dedicated to the annual variety; Visit this page for Information on Perennial Saponaria.

Annual Saponaria plants range from 15 to 90 cm (6 to 36 inches) in height. The plant Saponaria Vaccari, the anual cowherb/cow cockle is also referred to by the scientific name Vaccaria hispanica.

They carry lance shaped leaves, and come into bloom in spring (if sown in autumn) or summer (if sown in spring).

Flowers are usually flat and of pink or white. Some common names for annual varieties of Saponaria include Cow Herb and Soapwort. Their small size makes Annual Saponaria ideal for use in rock gardens.

Saponaria Vaccari
Saponaria Vaccari/Vaccaria hispanica by --Tico--.

How to Grow Annual Soapwort

When growing annual varieties of Saponaria, such as Soapwort and cowherb outdoors, the seeds should be sown on the surface. Do this either after the last frost of spring (for summer blooms) or at the start of autumn (for spring blooms).

Ideally Soapwort should be grown in a well drained sunny part of the garden, and spaced about 25 cm (10 cm) apart. The soil can be ordinary.

If you plan to start off Soapwort indoors, then start the process about a month and a half before you expect the last frost.

The seeds should be placed in moist soil, put in a plastic bag, then imbibed by putting in the fridge for about three weeks. The seeds should then be put into the light at a temperature of about 20°C (68°F).

It should take about one to three weeks for Soapwort seeds to germinate. Once ready transplant the young Soapwort outdoors following the last frost of spring.

Caring for Soapwort

Annual Saponaria plants such as Soapwort and Cow Herb are very easy to look after. Water them in the summer and in other prolonged dry spells. They should be lightly fed a couple of times during the growing season.

Common Questions

How many members does the Saponaria genus have?

The Saponaria genus consists of approximately 20 species, often known as soapworts.

Do members of Saponaria make a good garden or landscaping plant?

Saponaria plants are a good choice for gardens due to their attractive flowers and easy care. They're suitable for rockeries and borders.

Which Saponaria species are most frequently grown by gardeners?

The Saponaria officinalis (Common Soapwort) is commonly grown for its pretty clusters of pink flowers.

Are members of the Saponaria plant genus fragrant?

Some species of Saponaria, such as Saponaria officinalis, have a mild fragrance, especially in the evening.

What is the perfect location to grow Saponaria?

Saponaria prefers full sun to part shade and thrives in well-drained soil. It's drought-tolerant and does well in rock gardens or borders.

Is Saponaria invasive in the USA, if so in which states?

At this time, Saponaria is not considered invasive in the USA. Always consult local regulations for accurate information.

How do I remove Saponaria plants from my garden?

To remove Saponaria, dig up the plant, ensuring you get all the roots to prevent regrowth.


The Saponaria plant genus encompasses a variety of annual and perennial plants native to Europe and Asia. They are recognized for their small, fragrant flowers and their ability to produce a soapy lather when their leaves or roots are crushed.

To grow Saponaria, plant seeds, cuttings, or divisions in spring. They prefer full sun to partial shade and thrive in well-drained soil. Regular watering is necessary, particularly during dry periods, but overwatering should be avoided to prevent root rot.

I hope that you found this guide on how to grow Saponaria plants in your garden. You may also enjoy my gardening guides on how to grow Irish Moss, Dianthus plant, and Gypsophilia plants.