Annual phlox

Annual phlox: how do you recognise it?

Habit

Bushy annual 15–40 cm high and 25 cm wide, with upright, branching stems.

Leaves

Lance-shaped to oval, softly hairy, 3–7 cm long; the lower leaves are opposite, the upper ones alternate.

Flowers

Round clusters of small flowers with five petals and a long tube, from June to September.

Colour

White, pink, red, purple, salmon and two-tone, often with a contrasting eye.

Scent

Light and sweet, especially on warm evenings.

Flowering: June–September · Sowing: March–May · Plants: May

Why grow it?

• Flowers from June into September with round clusters in a wide range of colours.
• The lightly sweet-scented flowers attract bees and butterflies.
• Simple and inexpensive to grow from seed, in a pot or border.
• Compact and bushy (15–40 cm): pretty at the front of a sunny border or in containers.
• Good as a cut flower in small posies.

Annual phlox: where does it grow best?

• Full sun for the richest flowering; in light partial shade it becomes a little leggier.
• Free-draining soil rich in humus: sand or loam, acid to neutral.
• Evenly moist soil; in drought it wilts and is more prone to mildew.
• An open, airy spot, because in a dense, damp corner mildew sets in quickly.
• Plant 20–25 cm apart; in a container or pot you can set them closer, at 15–20 cm.

Light

Sun

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Normal

Size

0.3 m tall, 0.25 m wide

Hardiness

Frost tender: plant out after the last frost (mid-May)

Goes well with

• Cosmos: Airy flowers on tall stems above the low phlox.
• Zinnia: The same sun and warmth, with bold colours.
• Snapdragon: Upright spikes that contrast nicely with the round clusters.
• Pot marigold: Orange and yellow next to pink and purple make a cheerful summer border.

Annual phlox: when and how to plant it?

Plant in May.

1. Sow indoors in March–April and plant out after mid-May; sow outdoors in place from May.
2. Loosen the soil and mix in a few spadefuls of compost.
3. Plant the seedlings at the same depth as in their pot, 20–25 cm apart.
4. Firm the soil and water straight away, even if it is raining.
5. Spread a thin layer of compost or fine mulch around the plants to keep the soil moist.
6. In a 25 cm pot, put three to five plants in light potting compost.

Care

Water

Keep evenly moist, especially in dry weather. Water at the base and preferably in the morning, so the foliage stays dry.

Feeding

Once a month give a flowering-plant feed during flowering; too much nitrogen gives lots of leaf and few flowers.

Faded flowers

Cut faded clusters off just above a side shoot. This gives a second flush in late summer.

Pinching

Pinch out young plants at 10 cm for a bushy shape with more flowers.

Tidying

Remove dried-out plants in October and put them on the compost heap.

Tip: Cover the seed only lightly, because it germinates in the dark. Plant out after mid-May in full sun, keep the soil moist and cut faded clusters off for a second flush.

Annual phlox: when to prune it?

When: It is not really pruned; pinch out young plants in May and cut off faded clusters during flowering.

How:

• At 10 cm high, pinch out the tip of the main stem for more branching.
• Cut faded clusters off just above a side shoot or a pair of leaves.
• After the main flowering in August you can cut the plant back lightly to encourage a second flush.

Pruning calendar and basic rules

Propagation

Sowing (indoors)

In March–April: sow thinly in seed compost and cover the seed lightly, because it germinates in the dark. At 15–20 °C it germinates in 1–2 weeks. Prick the seedlings out into small pots and harden them off in May.

Sowing (outdoors)

In May, directly in place: sow thinly in rows and cover lightly. Thin to 20–25 cm between plants.

Collecting seed

In September–October: let a few clusters ripen, collect the seed capsules when brown and dry and store the seed cool and dry until next spring.

Annual phlox: how does it get through the winter?

Hardy to 0 °C: protect in harsh winters.

• Annual and not hardy: it tolerates at most a light frost around 0 °C and dies in harder frost.
• Clear the plants in October; seed that falls on the soil may germinate by itself next spring, but do not count on it.
• Store seed in a paper bag in a cool, dry place and sow again in March–April.

Diseases and pests

• Powdery mildew: White, powdery coating on leaves and stems, especially in drought and humid air. Give the plants space, water at the base, cut off affected parts and preferably choose resistant cultivars.
• Spider mite: Fine webs and yellowish speckles on the leaves in dry, hot air. Water, mist the leaves now and then and remove affected plants.
• Slugs: Young plants nibbled or eaten away. Collect slugs in the evening or set traps, and sow a little extra.
• Damping-off: Seedlings fall over at the base. Use clean seed compost, do not sow too thickly and do not overwater.

Through the year

• March: Sow indoors at 15–20 °C.
• April: Sow and prick out. Harden off by day.
• May: Plant out after mid-May or sow in place.
• June: First flowers. Pinch out late-sown plants.
• July: Full flower. Water and cut off faded clusters.
• August: Flowering. Cut back lightly for a second flush.
• September: Last flowers. Collect seed.
• October: Clear the plants.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• The plant is named after the Scottish plant collector Thomas Drummond, who sent seed from Texas to England in the 1830s.
• Phlox comes from the Greek word for ‘flame’, after the fiery colours of many species.
• Annual phlox is an exception in a genus of mostly perennials: the familiar garden phlox (Phlox paniculata) is hardy and returns every year.