Cut the stems down in late autumn to tidy up the plants and carefully collect and remove any fallen and dead leaves. Wash off the soil, and use a sharp, sterilised knife to cut off 5cm lengths of good, healthy roots. Phlox arrived in the UK as a garden plant from its native North America in the early 1800s and soon became a firm favourite for the summer herbaceous border. Garden phlox, or Phlox paniculata, is a perennial that blooms in late summer and comes in a variety of colors. Phlox is traditionally grown in herbaceous borders with other summer-flowering perennials such as lupins, Penstemons, Alchemilla mollis, Campanulas, roses, Heleniums, Echinaceas, Stachys, Achilleas, Delphiniums and hollyhocks. Parasitic nematodes (roundworms) are an infection that the plant gets from invasion by roundworms, and powdery mildew is exactly what the name implies: a mildew growth on the plant itself that can kill the phlox if left untreated. Keep the cuttings moist but not over-wet, moving the tray to a well-lit position once the green shoots emerge. The flowers are pollen and nectar-rich, and they attract hordes of pollinators such as honey bees, bumble bees and butterflies. The fragrant flowers are a delicate pale pink with a pearlescent quality. Phlox is very easy to grow and requires little attention, though plants can take a couple of years to establish fully and reach their maximum potential. It has dark green leaves and terminal panicles of fragrant, white-eyed, light lilac flowers with pale-edges to the petals. While it grows tall and looks healthy, it has never flowered. Propagation of the cultivars is easiest by division or root cuttings. Other more diminutive species grow in sunny rock gardens and shadier situations. During the move, the plants can be divided, using the outer part of the clump with healthy-looking shoots and discarding the old, brown, woody centre. The half-hardy annual group are useful as bedding plants and for growing in containers. Sometimes it is possible simply to pull rooted pieces from the edges of clumps without digging up the whole plant. This means they are intolerant of dry soil but will grow well if regularly mulched to maintain moisture retentive, humus rich soil in sun or part shade. Deadheading will keep fresh flowers coming through the summer. Other more diminutive species grow in sunny rock gardens and shadier situations. The name ‘phlox’ comes from the Greek for flame, perhaps making reference to the wild species’ vivid flower colours. All of this material should be burned or thrown away. Root cuttings are taken during early spring or in November. The half-hardy annual group are useful as bedding plants and for growing in containers. Phlox. The compost will need to be kept moist, always watering early in the day. Deadhead the plant and take out any damaged or untidy stems through the summer to encourage fresh growth and more flowers. Placing the tray on a warm surface will hasten growth, but it is likely to be mid-summer before roots are sufficiently established for the cuttings to be grown on. Affected plants can be used to take root cuttings before destroying them if desired. They should be planted in a sunny or partially sunny location. Once flowering stems have finished, they can be cut off to keep them looking tidy. Leaves Covered With White Powder Signal Powdery Mildew Powdery mildew is caused by fungi that live on the surface cells of a plant, coating infected leaves with a white or ash-gray powdery mold. It produces an abundance of clusters of scented, cerise flowers throughout the summer. Groups of five or seven are most effective. Growing to 75cm tall, ‘Mother of Pearl’ has fragrant, white flowers infused with delicate tinges of a blush-pink colour. Neither is terminal, and infection can be avoided or reduced through good care of the plants, ensuring they do not suffer water stress, providing adequate ventilation, and not watering late in the day. Whilst it is normally important to remember which way up the cutting was on the plant, any confusion can be avoided with phlox root cuttings by laying them flat in rows onto a 50:50 mix of potting compost and horticultural grit in a seed tray. Phlox is very susceptible to fungal infections such as leaf spot and powdery mildew. Some contemporary gardeners are rebelling against this tradition with less regimented designs, for example using taller but visually permeable plants such as grasses nearer the front of the border. A dose of water-soluble fertiliser in the autumn will also keep the plants vigorous. Slugs can be a problem with fresh spring growth. 222879/SC038262. Phlox arrived in the UK as a garden plant from its native North America in the early 1800s and soon became a firm favourite for the summer herbaceous border. The whole plant can be cut down to soil level in the autumn. This disease is first noticed by the powdery white spots or coating on plant tissues. ‘Prince of Orange’ is an erect, herbaceous perennial up to 80cm tall. When planting, add garden compost or well-rotted manure to enrich the soil. Established clumps can be divided in early spring every four or five years or so. Some phlox varieties are more susceptible than others and because it's a widespread problem newer varieties have been developed with resistance or tolerance, usually indicated on the plant tag. To take root cuttings, dig up the plant with as much of the root-ball intact as possible. Some cultivars have greater mildew resistance, and horticultural trials in the United States suggest that Phlox paniculata ‘Jeana’ is one of the best types to grow in badly affected gardens. A great choice for a pink variety, ‘Flamingo’ has fragrant flowers with a cerise eye. Phlox plants occasionally experience various leaf issues, with leaf spots typically inflicting the worst damage. While not generally grown in containers, phlox can make a colourful addition to a mixed summer patio planter, though the plants will still need air circulation and space if mildew is to be kept at bay – not always easy in a crowded planter. Split stems or distorted, misshaped leaves are likely to be signs of stem and leaf eelworm infestation. Read and follow … Feed the plants in early spring with a low-nitrogen fertilizer for best results. ‘Miss Pepper’ grows up to 1m high, but has sturdy and relatively wind-resistant stems.