As the common name indicates, the prairie mallow is native to the prairie grassland of North America, where it thrives in wild meadows, sunny woodland glades and streamside fields. And it is part of the mallow family, along with such excellent garden flowers as mallow itself, hollyhocks, lavatera, and hibiscus, among others.

Practically all members of the family are characterised by their relatively large open flowers, often flat, or very shallowly cupped and so it is with the prairie mallow too, or sidalcea, which is its botanical name. Sidalcea looks like a miniature hollyhock, with flowers opening up the stem.

The plant that sidalcea most resembles is the musk mallow, which is from southern Europe with pale pink flowers on an upright stem, sometimes seen as a garden escape.

This very pretty plant produces copious numbers of seeds, and seedlings pop up close to parent plants and further away when carried on boots or tools.

However, the prairie mallow, though similar, is far more elegant. Its stems are slender and the flower spikes more rigidly upright, the dark flower buds yet to open nicely bunched at the top of the stem. The stems are produced freely by the plant, rising from a dense clump of leaves close to the ground.

The plant flowers over a long period in summer, the flowers opening up the stem, and they last well in water and can be used as cut flowers.

Mostly pale-pink forms are seen and they are more summery. There are several named varieties, the best-known of which is ‘Elsie Heugh’ with light-pink satiny flowers that are frilled at the petal edges. ‘Rosanna’ is a dark pink-purple. ‘Party Girl’ has pink flowers, rounded more than others with a central white or pale pink area. ‘Oberon’ has clear deep-pink flowers. Pale-pink ‘Loveliness’ is relatively short, at 75cm, as most kinds can reach one metre and sometimes more. The light colours are airy and summery and the darker ones offer a more brooding contrast.

Plant sidalcea near the middle of a border, where its lovely flowers lift its surroundings, forming a pillar of pink. Apart from the flowers, which provide lots of colour from late June to September, the upright shape of the stems makes a good contrast to the rounded clumps of other good border flowers, such as phlox and monarda, which flower at around the same late-summer period.

Like many other flowers, sidalcea is best when it is repeated along a border, even only one repeat in a small border lends extra power to its flowering.

Sidalcea is easy to grow and not very choosy about soil. It likes moist soil, not likely to dry out, and it will frazzle up in a hot, dry summer on light soil. The weather has suited it very well this summer, as it loves a mixture of sunshine and showers, enough moisture to keep it growing steadily.

But it is not a wet-ground plant and likes the soil to drain well. The roots will rot away if the soil is wet in winter. The soil must be open but retain moisture and be fertile without being too rich, which causes the stems to be soft and flop about.

Despite these requirements, and full sunshine for best flowers, it is not tricky, it usually does well – but it does so much better if its requirements are met. CL

Mildew on courgettes

Powdery mildew disease is very common on courgettes and, to a lesser extent, on related plants such as pumpkins. The mildew is a fungus that appears as a few spots and soon spreads to the whole leaf. While it does not kill the plant or cause the leaves to rot, it reduces the efficiency of photosynthesis and results in slower growth. Not as many courgettes are produced when the disease has become severe, and sometimes very few more are produced. The young new leaves are not affected initially, but the fungus soon spreads to them too. The problem has not been as bad this year, because there was a good deal of rain until recently. The best way to avoid this disease is to choose a mildew-resistant variety. Watering in dry weather helps too.

>> This week

Trees, shrubs and roses

Trees and shrubs have grown very well, due to sunshine and lots of showers. Young trees and shrubs that look a bit tired can be given an application of liquid feed to boost their late-season growth before winter. Preparations for planting of trees can be made using glyphosate to kill existing grass and weeds.

Flowers

Spring bulbs are in the shops already and it is a good time to make an assessment as to new locations for bulbs to bring colour next spring. Bedding and container annuals will last longer if given some liquid feeding now. They still have a couple of months to go, but feeding and regular watering will keep them going.

Lawns

Lawns grew strongly with plenty of rain all summer, until the relatively dry spell in August, when grass stopped growing, especially on light soil. Mow less often until there is active fresh grass growth and do not apply any fertiliser until enough rain falls to restore soil moisture levels. Keep lawn edges trimmed for a neater look.

Fruit, vegetables and herbs

Many vegetables have done well this year and have already been used in some cases – cabbage and cauliflower, early carrots, French beans, broccoli and peas. Sweetcorn will be ready soon. Old crops should be removed when finished, and make sure not to let weeds get out of control. Keep weeds from shedding seeds.

Greenhouse and house plants

Keep picking greenhouse tomatoes, peppers and cucumbers as soon as they are ready and do not allow any new green fruit to develop — remove the flower trusses. Otherwise cropping tails off quickly. Stop feeding most greenhouse plants now, because they will have enough in the pot compost to keep them going.