MHG Volunteer Blog 36: Soapwort

It's time for the latest blog from our dedicated team of volunteer gardeners at Pontefract Castle.

Find out more about their blog series here.

This Monday, as with the weather in previous months, life managed to conspire against the MHG volunteers. Carole was on her own again.

After carrying out the flower count, she helped the Site Officer, Joe, by cutting back the planter by the Swillington Tower. She then, belatedly, started to cut-back the lavender bushes on the drive. “Started”, because with over 50 bushes it is not a task that can be completed in one go. Cutting back also, unfortunately, showed the weeds that had been hiding in the “undergrowth”. But that’s a job for another day.

The start of the lavender cut-back in the Medieval Herb Garden

Later in the day she enjoyed some time, easing her back and knees, by talking to visitors. There was a couple from Lockerbie in Scotland and two ladies from South Carolina, USA!

Plant of the week: Soapwort (Saponaria officinalis)

The name "Soapwort" comes from the plants ability to produce a soapy lather when its roots or stems are rubbed in water. The botanical name Saponaria derives from the Latin word for soap, saponem. 

It is also known as bouncing bet, latherwort, fuller's herb, bruisewort, crow soap, sweet betty, flop top, lady-by-the-gate, Jill-run-by-the-street, and Devil-in-a-bush.

Soapwort originated in Central and Southern Europe and Asia. It is classed as an ‘archaeophyte’. This means it was introduced to the UK before the 1500s AD.

It is a clump-forming, deciduous, stoloniferous, perennial. It will grow in almost any well-drained, non-acidic soil. It prefers to grow in full sun in any aspect. It can grow up to a height of 4 ft or more. However, at this height it tends to fall with the stems then bending upwards again. This forms a 'hollow crown' effect. Because of this, the plant in the MHG often only appears to be about 2 ft high.

The plant has green, leafy, unbranched, knotted, stems (often tinged with red). The broad, lanceolate leaves are opposite. They grow between 2 or 3 inches long and 1/3 inch wide.

Soapwort in flower in the MHG

The plant flowers between June to September. Its flowers have radially symmetrical, slightly downy, petals. The petals are pink or sometimes white. Each of the five flat petals is about 1 inch long. They are arranged in dense, terminal clusters on the main stem.

Unfortunately, this lovely plant has stoloniferous roots. These enable it to spread unless tightly controlled each year. Even in 1597 John Gerard wrote “if they have once taken good and sure rooting in any ground it is impossible to destroy them.” With this “truth” we can wholeheartedly agree!

Culinary uses of soapwort

Soapwort has a bitter, slightly sweet flavour. It has a lingering, pungent aftertaste and produces a numbing sensation in the mouth. Its main culinary use is in small quantities in traditional recipes like halva. Here, it provides a smooth, fluffy texture and acts as an emulsifier.

Please note: soapwort contains the toxic chemicals saponin and saporin. Eating the plant can lead to severe vomiting, fever, weakness, muscle pain, bleeding and damage to red blood cells.

Folklore and other facts about soapwort

When soapwort is steeped in water, it produces a mild soap. It was used in the woollen mills of Britain. Because of this, it naturalised in locations where the mills once stood.

In some western Asian countries such as Syria, it is still grown specifically for its use in cleaning wool.

Soapwort extract is used in some UK-based shampoos and soaps. It provides a mild, gentle lather.

The plant's cleansing properties led to its use in breaking witchcraft spells.

In the past, Dutch brewers have used the plant to get a good head on their beer. It is still used as an emulsifier in the commercial preparation of tahini and beer. It helps to create a stable head on the beer.

The flowers are visited by various insects including owlet moths (Noctuidae), hawk moths (Sphingidae), bumblebees and hoverflies.

Medieval uses of soapwort*

In traditional medicine, soapwort was used in a range of remedies. It was used as a diuretic, a purgative and for jaundice. It was also used as an expectorant prescribed for coughs and bronchitis.

The plant has natural cleansing and anti-inflammatory properties. This made it useful for treating skin conditions like acne and eczema.

*As always, this isn't to be considered medical advice today. Please don't use any plants mentioned in these blogs as medicine without advice from a doctor.