Plant Phlox in March for a Summer-Long Blaze of Colour

If your garden is still looking rather bare right now, one well-chosen plant can transform it in an instant - and keep it looking good all summer long.

Anyone who gets the spade out in March can look forward to a bright display from June right through into autumn. The plant in question is phlox: a perennial that was long dismissed as old-fashioned, but is now making a clear comeback in UK-style borders too - thanks to vivid colours, a strong fragrance and surprisingly little effort.

Why phlox is the plant that rescues summer

Phlox has an apt name: the word comes from Greek meaning “flame”, and that’s exactly the effect its flowers create in a border. Depending on the variety, shades range from crisp white and gentle pastels to rich raspberry red, violet, and even bicolours with a contrasting eye or striped petals.

“Phlox turns an ordinary border into a blazing summer scene - with scent, colour and an impressively long flowering period.”

Many hobby gardeners still associate phlox with a traditional cottage garden. That very sense of nostalgia is precisely why the plant is popular again, especially in naturalistic, rural-looking gardens. It partners beautifully with heritage roses, asters or coneflowers, and draws bees, bumblebees and butterflies in large numbers.

March is planting time: how to make the most of the window

March offers near-perfect conditions for planting phlox - both perennial and annual types. The soil is starting to warm up, yet still holds plenty of moisture. That gives plants time to establish strong roots and head into the growing season in good shape.

• Position: Sunny to lightly shaded; the more light it gets, the more profuse the flowering.
• Soil: Loose, humus-rich, fertile and free-draining, while not becoming bone-dry in summer.
• Plant spacing: 30–40 cm, so air can circulate around the leaves and fungal problems are less likely.
• Watering: Water thoroughly after planting; later, top up regularly, particularly during dry spells.

Planting in March sets you up for a colourful display from June well into autumn - and depending on the variety, even up to the first frosts.

The stars of the perennial border: tall phlox varieties

The best-known forms are the tall, perennial types, reaching up to 1.2 m and carrying dense clouds of flowers. They’re ideal towards the back of a border and also work well as cut flowers for the vase.

Panicle phlox: a classic with guaranteed fragrance

Panicle phlox (Phlox paniculata) produces large, scented flower heads and looks its best from June to September. Combined with asters, coneflowers or delphiniums, it creates a true cottage-garden feel.

Popular varieties include, for example:

• ‘Tenor’ - intense raspberry red, exceptionally bright in the border.
• ‘Orange Perfection’ - rare, striking vermillion tones, ideal as an eye-catcher.
• ‘Blue Paradise’ - blue-violet; the shade reads cooler or warmer depending on the light.
• ‘Bright Eyes’ - soft pink flowers with a darker centre, very romantic.
• ‘Fuji Yama’ - pure white and rather late-flowering, extending the season into late summer.

Spotted phlox: earlier and slightly slimmer

Spotted phlox (Phlox maculata) stays a little narrower, but makes up for it with bold, candle-like flower spikes. It generally flowers a touch earlier, roughly July to August, and reaches 80 cm to 1 m tall.

Interesting varieties:

• ‘Alpha’ - sweet pink with a slight violet sheen in places, flowering through into September.
• ‘Natascha’ - white-and-pink striped blooms that stand out immediately.

Gap-fillers with long flowering: annual phlox for pots and borders

Drummond phlox: small, but relentlessly floriferous

If you want a genuine wave of flowers from spring until the first frosts, choose Drummond phlox (Phlox drummondii). These annuals stay much lower at around 20 to 40 cm, but compensate with an exceptionally long and generous flowering period.

The colour range leaves little to be desired:

• From pure white through cream and salmon to bold red and deep blue.
• Bicolours with a contrasting eye or striped petals.
• Colour mixes that practically flood window boxes, pots and border edges.

Drummond phlox is equally happy in the ground or in containers, window boxes or bowls. It’s especially suited to city balconies: it takes up very little space while delivering maximum colour impact.

Where phlox makes the biggest impact in the garden

Phlox is considered a versatile all-rounder for ornamental gardens. It slips surprisingly easily into different styles - from a more formal perennial border to a wilder, nature-inspired planting.

Typical ways to use it:

• In a mixed perennial border: With asters, coneflowers, purple coneflower or lady’s mantle, it creates an airy, colourful summer look.
• Along fences or in front of a fence: Taller varieties hide unattractive areas and form a flowering backdrop.
• In a pot or bowl: Compact forms, such as Drummond phlox, add colour to balconies and patios.
• As a cut flower: Panicle phlox lasts well in a vase and brings scent and colour indoors.

“If you position phlox thoughtfully, a handful of plants can add depth to a border and create a harmonious transition from front to back.”

Golden rules for healthy phlox

To keep phlox thriving for years, it helps to stick to a few care basics. While it’s generally easy-going, it does have clear preferences.

Aspect	What phlox likes
Planting time	Perennial varieties in spring or autumn; sow annuals into borders from late spring
Light	Sun to light partial shade
Soil	Fertile, loose, never completely dried out in summer
Care	Remove spent flowers, feed occasionally with compost
Rejuvenation	Divide perennial varieties every few years in autumn

One point that’s often underestimated: phlox can be sensitive in persistently damp, poorly ventilated spots. That’s where powdery mildew can take hold, showing as whitish-coated leaves. A better choice is a position with airflow, good soil and spacing that isn’t too tight.

Practical tips for longer flowering and stronger plants

With a bit of care, you can get even more from your plants. A few small adjustments make a noticeable difference:

• Work in a thin layer of compost in spring - this supports strong growth.
• Cut off faded flower heads to encourage fresh blooms and keep self-seeding in check.
• In very hot summers, water deeply in the morning rather than giving frequent light sprinkles.
• If mildew appears, prioritise resistant varieties or respond early with approved treatments.

By combining several varieties, you can extend the flowering season: early, mid-season and late options help ensure the border never looks empty from early summer into autumn. Mixing whites, pastels and bold shades also adds energy - white acts like a “light switch” in the border, making neighbouring colours appear more intense.

The effect in partial shade is worth noting too. Cooler violet and blue varieties look especially striking there, as they almost glow in softer light. In full sun, on the other hand, vivid reds and bicolours come into their own, staying visible from a distance and giving the garden structure.

If you put a few pots of phlox in your trolley this March, you’ll be laying the groundwork for a summer that definitely won’t be short on colour. With minimal effort, a few clear rules and the right choice of varieties, an average border becomes a place you’ll want to linger on warm evenings.