The soft-pink flowers of soapwort are quite eye-catching, but perhaps not eye-catching enough for people to enquire about it or to look it up, simply passing it off as some wild flower. However, when you do know what the plant is, you will see it all over the place.

For several weeks now, soapwort has been flowering by roadsides in many parts of the country, mainly the east. When spotted, it is usually close to a house or the ruins of an abandoned place. It can sometimes be seen away from houses, but always still by roadsides. It would not be seen in open countryside, away from houses and roads. These are signs of a plant that might be so natural that it appears to be native, but it is not. It is what’s called a ‘garden escape’.

A garden escape is a plant that is, or was, cultivated in gardens, but has made its way into the wider environment. Soapwort is botanically called Saponaria officinalis, the first part meaning ‘soap-maker’ and the second means ‘sold in shops’, which is a reference to its use as a herbal remedy for skin and respiratory ailments. Wort is an old English word for a plant, often a plant that had a practical use or was used medicinally. Sometimes it is pronounced incorrectly as ‘worth’.

As a bioactive plant, saponaria contains a group of chemicals called saponins, which are soap-like in action, and these can be 5% or more of the plant’s weight. These compounds are used by the plant as poisons to prevent grazing, and no grazing animal will touch it, including deer or rabbits. Not that they are deadly poisons, they are not, but they offer a nasty taste, like having a mouth full of soap. This is part of the reason why soapwort has survived so well, long since its medicinal and cosmetic values were superseded.

The saponins can be released by chopping up the leaves or roots and boiling them in water. When the boiled leaves or roots are removed, the remaining strained liquor can be used as a gentle soap or shampoo, and that was the reason for growing it. Since ancient times it has been used for washing wool. Despite being potentially distasteful, it has also been used in tiny amounts to put a foamy head on beer. Related to carnations, and sweet William, soapwort normally has five flat petals.

The form seen growing by roadsides is almost always double-flowered with more than five petals, another sign that it is a cultivated plant that has escaped.

Although it is invasive, it can be grown quite happily in a semi-wild corner, in sunshine or part-day shade. And it is at home in country garden, forming a big robust clump of pretty, pink flowers.

Its robust nature is the other reason it has survived so well. It is well able to compete with roadside grasses and other wild plants, even nettles. It can grow to about 60cm and produces stolons to spread itself outwards. It is not unusual to see a clump several metres in length by a roadside.

It seems to favour a well-drained, even dry spot. Soapwort is rarely seen for sale as it’s such a runner, but it is easily raised from cuttings of the stem in summer, even while flowering, and from divisions, or just pieces of the roots in autumn or winter. It is a true cottage-garden plant, with pretty flowers and a sweet, light scent. CL

Plum disease

This summer, there appears to be an increased incidence of a damaging disease of plums, called pocket plum. The disease gets the name from the elongated shape of the affected plum, making them longer and sometimes with a groove on the incurving side. If the young fruit is cut open, there is no stone inside, the fungus having affected normal fertilisation.

The outside of the fruit may have a coating of dark-coloured fungal growth, though not always. In general, not all the plums on a tree are affected, but they can be and the whole crop can be lost. If a plum tree has been affected, rake up or pick up all fallen fruit and remove any left on the tree. Burn or bury them to reduce the chances of infection next year.

Trees, shrubs and roses

Shrubs planted from pots during recent months may still need watering. Make sure all existing grass and weeds are dead before autumn planting. This usually means two applications of glyphosate-based spray. Good results will be achieved, as there is still some warmth and weeds are weaker.

Flowers

Continue feeding and watering baskets and other containers on a regular basis. Stay on top of weeding in flowerbeds and borders. Prevent weeds from going to seed. Collect seeds of perennial flowers to raise new plants, eg aquilegias. Take cuttings of tender plants to carry over winter.

Fruit, vegetables and herbs

Sow winter lettuce and spring onions. Raspberry canes that have finished fruiting could be pruned out and new canes tied into position – if there are too many, reduce the number to about 10-15 per metre of row. Tying down branches of young apple trees horizontaly will help early fruiting.

Lawn

Rainfall amounts have kept grass going in most areas. Most lawns are growing well and probably benefiting from the natural release of nitrogen that occurs during summer. Any lawn that is not looking good will benefit from feeding with high-nitrogen fertilisers in rainy weather until the end of the month.

Greenhouse and house plants

Take the tops off tomatoes to encourage the green fruit that is already present. Tidy up plant debris from the greenhouse. Be careful not to overwater or splash water about. From now on, grey mould disease becomes a problem in greenhouses and good hygiene is the best way to avoid it.