Phlox Care Guide: How to Grow Phlox

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The Phlox genus encompasses almost 70 species, also includes annuals, perennials and shrubs. Most of the perennial varieties are upright, but a couple of species are dressed forming. Most of all the popular garden varieties derive from the species Phlox paniculata, a tasteful, erect, herbaceous perennial with sword-shaped leaves. It creates loose, branching clusters of five-petalled flowers (or panicles, therefore’paniculata’).   These are typically white, pale lilac or darker purple and continue to seem throughout the summertime and into the early fall.

Phlox arrived in the UK as a garden plant by its native North America in the ancient 1800s and became a firm favourite for the summer herbaceous border. The plants not just create plenty of color but also a delicious aroma that arouses the very character of a traditional English cabin garden. The flowers are pollen and nectar-rich, plus they bring hordes of pollinators like honey bees, bumble bees and butterflies.

The title ‘phlox’ stems from the Greek for fire, possibly making reference to the wild species’ vivid flower colours.

This article focuses on caring for the upright, herbaceous, perennial phloxes.

  • Jump To:
  • Overview
  • Varieties
  • Care
  • Propagation
  • Problems
  • FAQs

Plant Overview

Common Name Phlox, summer phlox( perennial phlox
Scientific Name Phlox paniculata
Plant Family Polemoniaceae
Origin North America
Height Around 1m
Light Sun or light color
Temperature Established plants will cope with temperatures below freezing
Hardiness Hardy
Soil Rich, moisture retentive but well drained loam
Fertiliser Blood, fish and bone in spring and also water soluble fertiliser in fall
Propagation Division, soft cuttingedge, root cutting
Pests Slugs, eelworm, mildew and other fungal infections
Difficulty Easy

Phlox Varieties

A wide assortment of phlox cultivars is available from nurseries and garden centers.  Many different colors are created, though the many frequent varieties are usually white, pink, purple or blue. Orange and reddish varieties also have been created.  There will also be cultivars with two-coloured flowers, plus some with variegated foliage.

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The following list includes some of the hottest, reliable and widely available cultivars. All have been given the RHS Award of Garden Merit following a variety of horticultural trials over several decades.

Phlox paniculata ‘Uspekh’

‘Uspekh’ is a herbaceous perennial, growing up to 1m high. It has the typical green, lance-shaped phlox leaves and blossom, purple flowers with a white star at the center during mid to late summer.

Phlox paniculata ‘Miss Ellie’

A bushy, upright herbaceous perennial growing up to 1m high, ‘Miss Ellie’ includes dim, lance-shaped leaves and lush panicles of fluffy, rose-pink and aromatic flowers from mid to late summer.

Phlox paniculata ‘Prospero’

‘Prospero’ develops to 90cm tall. It has dark green leaves and terminal panicles of fragrant, white-eyed, light lilac flowers with pale-edges to the petals. It is earlier flowering than many, blooming from the beginning of summertime.

Phlox paniculata ‘Danielle’

A briefer, strong and weather-resistant variety up to 70cm tall, ‘Danielle’ generates clean white flowers with an excellent scent over an elongated period during the summer.

Phlox paniculata ‘Prince of Orange’

‘Prince of Orange’ is an upright, herbaceous perennial up to 80cm tall. It produces panicles of very fragrant, vibrant, orange-red flowers in mid summer.

Phlox paniculata ‘White Admiral’

One of the popular white varieties of phlox, ‘White Admiral’ is upright and develops upward to 90cm in height. The flowers are beautifully aromatic and are made from the middle of the summer into early fall.

Phlox paniculata ‘Rosa Pastell’

‘Rosa Pastell’ develops upwards to 70cm high. The variety has dark stems and striking, loose heads of dark pink buds which open into highly scented, pink flowers with a darker eye during the summer.

Phlox paniculata ‘Blue Paradise’

This tall variety can grow up to 1.2m in height, and normally requires staking in an open edge. The curved heads of blossom, dark-eyed violet-blue flowers appear in summer time, also bring a beautiful ancient fragrance to the herbaceous border.

Phlox paniculata ‘Grey Lady’

‘Grey Lady’ is a bushy but upright perennial, growing up to a height of 1m.   The blossoms are a delicate shade of light lavender-grey, with a beautiful aroma. Flowering occurs from ancient to mid summer.

Phlox paniculata ‘Miss Pepper’

‘Miss Pepper’ develops upwards to 1m high, however contains hardy and relatively wind-resistant stems.   Its sweetly fragrant pink petals frame a dark pink eye, and are endorsed by contrasting purple sepals.

Phlox paniculata ‘Le Mahdi’

‘Le Mahdi’ is a clump-forming herbaceous perennial to 1m tall, with black foliage and panicles of fragrant violet-blue flowers.

Phlox paniculata ‘Flamingo’

A fantastic choice for a pink variety, ‘Flamingo’ includes fragrant flowers with a cerise eye. This cultivar grows up to 1.1m high.

Phlox paniculata ‘Mother of Pearl’

Growing to 75cm tall, ‘Mother of Pearl’ includes black, white flowers infused with delicate tinges of a blush-pink color.

Phlox paniculata ‘David’

A fantastic choice for the white backyard, ‘David’ has a bushy and upright shape and reaches a height of a metre, or more in great conditions. It includes a bunch of very fragrant, pure white flowers from mid to late summer.

Phlox paniculata ‘Grenadine Dream’

A briefer, hardy and self-supporting variety, ‘Grenadine Dream’ develops upward to 60cm high. The dark green leaves provide a contrasting background to the pleasantly scented, reddish-purple flowers from mid to late summer.

Phlox paniculata ‘Monica Lynden-Bell’

‘Monica Lynden-Bell’ is another shorter variety, reaching to 80cm in height. The blossom flowers are a delicate pale pink with a pearlescent quality.

Phlox × arendsii ‘Miss Mary’ (Spring Pearl Series)

The hybrid ‘Miss Mary’ develops upward to 1m in height, and contains more oval-shaped leaves compared to many garden phloxes. It creates plenty of clusters of scented, cerise flowers throughout the summer.

Phlox Care

Phlox is quite simple to increase and requires little attention, though crops may take a few decades to establish entirely and attain their maximum potential.

They ought to be planted in a sunny or partially sunny location. Space them out well, at least 30cm apart and away from other crops, to ensure decent ventilation, since they are vulnerable to mildew.

Prepare the floor for planting by digging in certain garden compost or other fertile organic thing.   Ensure the mulch in the pot matches the degree of the surrounding soil when preparing the gap and planting out.

Phlox are hungry crops, so use a 5cm to 10cm dressing of backyard mulch or well-rotted manure each spring.

Most forms of phlox have sturdy stems and are self-supporting, but a few of the taller varieties will require staking with canes, hazel sticks or herbaceous perennial loops in windy gardens.

Once flowering stalks have finished, they may be cut to maintain them looking tidy. The entire plant could be cut to soil amount in the fall.

Some enthusiasts advocate a spring movement of phlox plants each four or five decades, since they may deplete the soil of certain nutrients, and to help stop the build-up of disease. During the move, the plants could be divided, using the outer portion of the clump with healthy-looking shoots and discarding the older, brown, woody centre.

Light requirements

Phlox favors a position in full sun, although it will still grow well in a little light color.


Do not water phlox late in the evening or during the night since this may facilitate the establishment of powdery mildew. Water the soil round the plants well in the morning to permit any splashes on the leaves time to dry out earlier the conditions become more humid about nightfall.

Soil conditions

The plant requires quite good, rich, well-drained soil. When planting, include garden mulch or well-rotted manure to enrich the soil.


Plants and flowering could be improved by providing them with a sprinkling of blood, fish and bone annually previously the spring mulching with rich organic matter.

An dose of water-soluble fertiliser in the fall will even keep the plants vigorous.


While not normally grown in containers, phlox may produce a colourful addition to a mixed summertime patio planter, although the plants will still need to have air circulation and distance if mildew is to be maintained at bay — perhaps not always easy in a crowded planter. The container demands to be well drained, big and profound in order to adapt the plant and its origins. Use a fantastic quality potting compost with 25percent perlite to improve drainage.

After planting, water the container liberally to settle the soil round the roots, trying to avoid wetting the foliage. The compost will require to be stored moist, constantly watering early in the day. Deadheading will maintain new flowers coming through the summer.

If mildew does impact the plant, so it is best cut to soil degree. Plants that remain healthy ought to be cut to 5cm in the fall, and they will re-sprout following spring.

Looks great with

Phlox is traditionally grown in herbaceous borders with other summer-flowering perennials such as lupins, Penstemons, Alchemilla mollis, Campanulas, roses, Heleniums, Echinaceas, Stachys, Achilleatherefore, Delphiniums and hollyhocks.

Herbaceous perennials are usually increased in uneven-numbered groups for the best effect, assuming there is space in the border. Groups of five or seven will be most effective. Borders were traditionally laid out with the taller crops in the ago, mid-size kinds like phlox in the middle and shorter plants in the front. Some modern anglers are rebelling against this tradition with significantly less regimented designs, such as using taller but visually permeable plants like grasses closer the front of the border.



Deadhead the plant and also take any damaged or untidy stalks through the summertime to encourage new growth and more flowers.

Cut the stalks down in late fall to tidy up the plants and closely accumulate and remove any dead and lost leaves. All of this material ought to be burnt or thrown off. It shouldn’t be inserted to the compost heap to decrease the risk of re-introducing eelworm and mildew to the boundary in the following calendar year.

Phlox Propagation

While several kinds of phlox for example Phlox drummondii are available as seeds, the more prevalent Phlox paniculata cultivars are purchased as bare root or container grown plants.

Propagation of the cultivars is easiest by division or root cuttings.

Established clumps can be divided in early spring each four or five decades or so. Separate the clump into sections, discard the older, woody center, and plant the sections into the border straight away, watering in well but not waterlogging.

Sometimes it is possible simply to extract suspended pieces from the borders of clumps without digging up the plant.

Root cuttings are taken during early spring or in November. Phlox has rather fine roots which are a bit more fiddly to take cuttings from, however the technique is usually profitable. Only take cuttings from vigorous and healthful crops to avoid spreading or perpetuating disease, especially viruses.

Root cuttings are a fantastic method of overcoming eelworm issues without losing plants entirely, as the eelworms rarely infect the plant under soil level, so fresh plants derived from root cuttings will typically be unaffected.

To take root cuttings, dig the plant with too much the root-ball intact as possible. Wash away the soil, and use a sharp, sterilised knife to cut 5cm lengths of great, healthy follicles. Whilst it is generally important to recall which way upward the cutting was on the plant, any confusion could 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. Cover them shallowly with compost. The new roots emerge from 1 end of the root cutting and the shoots from the other.

Keep the cuttings moist but not over-wet, moving the tray to a well-lit position once the green shoots emerge. Placing the tray onto a hot surface will accelerate expansion, but it is likely to be more mid-summer until follicles are sufficiently established for the cuttings to be increased on.

Common Phlox Problems


Slugs may be a issue with brand new spring development.

Split stalks or distorted, misshaped leaves are likely to be signs of stem and foliage eelworm infestation. There is no treatment, therefore affected plants must be dug up and destroyed. Replacement phlox plants must be grown elsewhere in the backyard, and great garden hygiene imposed, removing all dead leaves. Affected plants may be utilized to take root cuttings before destroying them if desired.


Phlox is quite susceptible to fungal infections like leaf spot and powdery mildew. Neither is terminal, and infection can be avoided or reduced through care of the plants, ensuring they don’t suffer water pressure, providing sufficient ventilation, rather than watering late in the day. The best way to prevent mildew is to maintain the soil rich by mulching liberally in the spring.

Extra attention is necessary in the early summer when the times are hot and the nights cool.  Mildew flourishes in conditions of fluctuating temperatures, and the plant is much more susceptible when the foliage is wet or if it is suffering breakage.

Some cultivars have higher mildew resistance, and horticultural trials in the United States imply that Phlox paniculata’Jeana’ is just one of the best forms to increase in poorly influenced gardens.  The species Phlox amplifolia also achieved quite well, even though it is not widely available in the UK.


Q The phlox scents beautiful at the much end of my boundary — will it perform well in the vase if I utilize it in an arrangement for the dining table?


Phlox is fantastic for indoor structures, however the flowers will require to be considered after to remain their very best. Do not utilize flowers cut from crops which are clearly influenced by mildew, and reduce some leaves from the stem prior to placing the flower in the vase. Provide a few ferny foliage to set off the texture and color of the flowers.

Q My phlox has been growing in a sunny edge with a few Achilleas for five decades. While it grows tall and seems healthy, it hasn’t flowered. There is not any sign of mildew or foliage distortion. What is the issue?


If the plant appears to be green, lush and usually healthy, it might well be that the nitrogen to potassium ratio in the soil is skewed, favouring the production of foliage within flowers. Many herbaceous perennials are bashful flowerers when they are over-provided with nitrogen and under-provided with phosphorus. Review your feeding regime, also in the first instance give the plant a great dressing of bone meal.   Going ahead, utilize a high potassium fertiliser like sulphate of potash or tomato feed in late night.

Q What forms of phlox are ideal for my wildlife backyard?


Most forms of Phlox paniculata provide lots of pollen and nectar for pollinating insects. Research in the US evaluated 137 species and varieties of phlox for blossom appeal and discovered that the cultivar Phlox paniculata ‘Jeana’ was particularly attractive. The flowers of  ‘Jeana’ are one of the tiniest of phloxes, even though they are nevertheless attractive to gardeners as well as insects.  The sprays of candy-pink flowers are sweetly scented, and expand on tall stalks up to 1.2m tall.

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