The blue-purple flowers of strobilanthes have been exceptionally good this year, probably due, as with many other plants, to the mixture of sunshine and showers that has been more or less unbroken since early June.

It contrasts well with autumn colour foliage and late yellow flowers, such as rudbeckia, heleniums and helianthus. It is a perennial flower of medium size, capable of reaching about 1.2m tall or a bit more with older plants.

It can grow to at least the same in width and often more, as the clump spreads slowly. It does not come into flower until late summer, and this means it takes up space while it grows to flowering stage.

A small garden cannot afford so much space even if the plant is valuable. But it suits a large garden or a rural garden very well where it fills space effectively.

The plant grown in gardens is the species as originally collected from the wild — it has not been changed, so it looks very natural and it has plenty of vigour.

It is a most understated plant, often it is not noticed until you are right beside it. At other times, a glance across its broad rounded top catches a crescent of intense blue colour.

The flowers are not large but numerous, and they have bloomed in greater numbers this year. Each flower is about 4cm long, shaped not quite like a trumpet because it has a bend in the tube, but it has a frilled trumpet-like front, intensely coloured. The flowers are carried in branching clusters and open from buds in succession, which is why the flowering period is so long, extending from August to October.

The longevity of the flowers depends on sunshine. In a nice sunny year, it keeps going, but if it is hammered by rain and cold winds, it soon begins to shut up shop for winter.

This plant is not much seen for sale, unfortunately, but it seems to have been passed around over the years, because it appears in old gardens, even small cottage gardens, often as a big clump. It would seem to be very good at surviving in competition with other plants, undoubtedly because of its dense mesh of stems and leaves.

The leaves are nettle-like in appearance and have a musky smell when crushed, earning it the unflattering name of “stinking nettle”, though it is not even related to nettles.

It is also known as the ‘wild petunia’ or the Mexican petunia. Strobilanthes atropurpureus has no common name that is used, so it is known by its botanical name, strobilanthes, which is correctly now Strobilanthes wallichii.

The plant is neither Mexican or has any connection with petunias either, which are part of the potato family. It is a member of the acanthus, or bear’s breeches, family and it comes from the Himalayan region of India.

There is a tender related plant called Persian shield because of the shield-shaped purple leaves, occasionally used as a summer bedding plant, or in tropical bedding schemes, its dark purple leaves contrasting well with colourful flowers.

Because strobilanthes is late-flowering and does not offer much more than nettle-like foliage before it flowers, try to have something with colour in the early part of the summer placed in front of it, such as Oriental poppies or dicentra, which wither away in summer.

It looks great with the taller Helianthus ‘Lemon Queen’ in the background. It is a robust plant, well able to resist weeds and the competition of other plants. Give it reasonably good soil, well-drained, though not too dry, and a sunny position for maximum flowering, and it is hardy. CL

>> This week

Fruit, vegetables and herbs

The vegetable garden needs to be tidied as crops go over. Crops left in the ground can help the carryover of pests and diseases, and it is good hygiene to clear them out as they become unusable. Fruit crops can be picked and stored, using flat shelves or trays for pears and plastic bags, open at the neck, for apples. Weeds should be removed.

Flowers

Bedding that is gone over can be removed in preparation for planting spring bedding and bulbs. The next few weeks are the main time for planting spring bulbs and containers for spring display. The garden shops all have their spring bedding in now. Perennial flowers can be planted or lifted and divided in the case of existing plants.

Trees, shrubs and roses

Control weeds around the base of young trees and hedges. Tree and shrub planting can take place now for evergreens. Deciduous kinds and hedges planted bare-root must wait until leaves fall. Check that trees recently planted are properly staked, and stake any old shrubs that appear top-heavy. Check that the support on wall-trained climbers is solid.

Lawn

Good growth all summer has seen moss become a problem in many lawns, especially on acidic soils. Sulphate of iron can be applied if moss is a problem. Use either an autumn lawn fertiliser or a low- nitrogen compound fertiliser, which will maintain growth through the winter and leave the lawn in good condition.

Greenhouse and house plants

Place rooted cuttings in a bright position. Stop feeding house plants and reduce watering. Most of the greenhouse crops can be cleared soon. Throw out any old plants that are past their best, as they are a source of pests and diseases. Tidy up all debris and reduce watering to just keep pots from going completely dry.

Picking Bramley apples

‘Bramley’s Seedling’ is by far the best cooking apple and easily the most widely grown, and most trees yield some apples every year, some years more. Many apple trees – not just Bramley – are carrying a good crop. So much so, in many cases, that ripening, despite good temperatures is a bit behind the usual season. ‘Bramley’s Seedling’ normally ripens in early to mid-October, in some years later.

Apples continue to ripen while there are leaves on the tree. The longer the fruit is left to ripen, the better it will keep in winter, and Bramley can last into spring in good conditions. In the meantime, use up windfalls, of which there are plenty, and pick the rest when they colour up and come away easily from the twig. Store in unsealed plastic bags in a cool shed.