Covered with lots of bright blue flowers, leadwort is a delight of the autumn garden. It starts to flower in August and continues well into September and even October in some cases.

Although the flowers are small, they are carried in clusters at the tips of the shoots. The individual flowers do not last very long, shrivelling up after a few days, but they are produced in large numbers from the gathered buds at the shoot tips. The effect of the little bush and its flowers is very striking and carries much more impact than might be expected. The shade of blue is intense, but clear and bright and cooling.

Leadwort is a funny little plant. It not widely grown but it appears from time to time in gardens, picked up in a garden centre because of its bright blue flowers. The name is assumed to be a reference to its blue colour. It is part of the plumbago family, plumbago meaning lead-linked. The family is named after the Cape leadwort, plumbago capensis, a very beautiful climber grown in warmer countries and for growing in a conservatory here where it flowers for perhaps 10 months of the year. Long flowering is one of the family traits. Being from the Cape of South Africa, plumbago is not very hardy and that is why it needs to be grown in warm conditions. Its small shrubby cousins are much more hardy but they can be damaged by frost in a cold winter.

There are two main kinds grown: Ceratostigma plumbaginoides and Ceratostigma willmottianum. Native to China, the first one is a perennial plant arising from a woody base. It is about 50cm tall and has rhizomes that spread under the soil surface. It can be a bit of a spreader in ideal conditions and it needs to be given a bit of space at the front of a border, but it is easily controlled if necessary.

As autumn progresses, its leaves take on a rich red colour that is enhanced by the blue flowers. The shrubby leadwort, Ceratostigma willmottianum, is also of Chinese origin. It is much bigger than the one already mentioned and is a true shrub, reaching about one metre tall and twice that in width. It has red-brown stems and carries bright blue flowers. Its leaves change colour to fiery shades of orange and red before falling. The blue flowers look good with any sort of autumn colour nearby and they beautifully enliven any plant with silver foliage, such as lambs-ear or verbascum.

Leadwort is easy to grow in any reasonably fertile – but not too rich – soil. Rich soil tends to make the plant very leafy at the expense of flowers. The soil should be fairly light and well-drained in winter. Because the plant can be damaged by severe frost, it has a better chance when grown in light, well-drained soil because its stems will be a good deal harder and more resistant to frost than if they are grown soft in rich, fertile soil that has a good deal of moisture.

But the plants must not be starved of moisture either. The shrubby leadwort is the hardiest of the family but can be cut to the ground by hard frost and will sprout again. It can be trimmed back in spring to keep it neat. One kind is perennial, the shoots withering back, and the more shrubby kind can also be treated as a perennial and cut back to keep it small. In fact, frost may do this naturally. CL

Butterflies as láthair

Butterflies have largely been absent this summer. There are still butterfly days ahead, of course, because butterflies can appear late in the season, but the numbers have been a tiny fraction of a normal year and an even smaller fraction of a good year, such as last year. Only the occasional cabbage white was seen, which is a mixed blessing, and few, if any, others. A cold and wet spring and a cold, rainy summer, has destroyed caterpillars of native species, such as small tortoiseshell. Summer migrants from the continent, such as red admiral, have had to contend with near-continuous cold winds from a northerly direction, not an encouragement to fly north. The same cold, unfavourable weather has kept wasp numbers low, nor are houseflies numerous this year.

Trees, shrubs & roses

If planting bare-root trees this autumn, make sure all existing vegetation is completely killed before planting begins. This usually means two applications of Roundup or similar glyphosate-based spray. Check the ties on young trees are not rubbing. Shrub roses and ramblers can be pruned by removing shoots that flowered.

Fruit, vegetables & herbs

Raspberry and tayberry canes that have finished fruiting can be pruned out and the new canes tied into position. If there are too many canes, reduce the number to about 10 or 15 per metre of row. Finish off any remaining summer pruning of over-vigorous apples and pears, shortening the long whippy shoots.

Flowers

Continue to prevent weeds going to seed in flower beds and borders, as it has been a showery and weedy summer. Continue feeding and watering baskets and other containers regularly. Buy spring bulbs and plant them as soon as possible — the fresher they are going into the ground, the better they will flower.

Lawn

Moss has grown most of the summer and can be controlled now with sulphate of iron. Continue mowing regularly and apply an autumn lawn feed to give the grass a boost going into autumn. Prepare now for sowing new lawn areas, or re-sowing old lawn this month or next. Keep edges neat around beds and borders.

Greenhouse & house plants

As the nights grow cooler, grey mould disease becomes a problem for many greenhouse plants and good hygiene is the best way to avoid it. Tidy up the greenhouse now and do not overwater or splash water about. Continue to train and side-shoot tomatoes and cucumbers. Allow only existing fruit to develop.