Plant Phlox in March for a Summer Fireworks Display of Blooms

Think about summer now: anyone choosing the right perennial in March can fill their borders with a months-long fireworks display of blooms.

In spring, many amateur gardeners first turn to tulips, daffodils and pansies. Yet there is one plant that can be planted quietly in March before transforming entire borders into glowing clouds of colour from June well into autumn: phlox. This traditional cottage-garden favourite is enjoying a major revival, for very good reason.

Why phlox is considered a summer gem

Originally from North America, phlox takes its botanical name from the Greek word for “flame”. Anyone standing before a dense phlox border at the height of summer will instantly see why: its flowers are packed so closely together and are so richly coloured that they seem to blaze.

Phlox brings uninterrupted colour to the garden from early summer until autumn – and requires remarkably little effort.

Its colour range is enormous, stretching from pure white and soft pastel shades to vivid raspberry red, purple and violet. Many varieties produce bicoloured flowers with a darker eye or delicate stripes – ideal for creating borders that feel lively rather than overly neat and uniform.

March: the ideal month for planting phlox

Planting in March gives these perennials a head start. The soil is no longer frozen, while still retaining enough moisture. New shoots can establish without heat stress, roots have time to settle in, and the reward is abundant summer flowering.

• March: the best time to plant perennial phlox varieties
• from late April: sow or buy annual varieties for pots and window boxes
• flowering: depending on the species, from June until the first frosts

Those who hesitate now may lose an entire season. Phlox is one of those plants that makes substantial growth even in its first year – but only if it reaches the border early enough.

The most important phlox types for the home garden

Tall garden phlox: a classic for generous borders

The best-known type is tall garden phlox (Phlox paniculata). Depending on the variety, it grows from 50 centimetres to well over 1.20 metres tall and produces huge, fragrant flower clusters. It is ideal for the middle or rear of a border.

Popular varieties include:

• ‘Tenor’: intense raspberry red, ideal for anyone who likes colour with real impact.
• ‘Orange Perfection’: bright vermilion that immediately catches the eye in any perennial border.
• ‘Blue Paradise’: an intriguing blue-violet shade whose appearance changes with the light.
• ‘Bright Eyes’: soft pink flowers with a dark centre, wonderfully romantic in a cottage garden.
• ‘Fuji Yama’: brilliant white, flowering late and therefore extending the phlox season into autumn.

These varieties work superbly as a flowering backdrop behind roses, coneflowers or asters. Gardeners who enjoy cutting bouquets will also have a constant supply of fresh vase material with tall phlox.

Spotted phlox: earlier flowering with a slimmer form

Less widely known but particularly appealing to collectors is spotted phlox (Phlox maculata). At around 80 centimetres to 1 metre tall, it remains somewhat shorter, has a more slender appearance and carries flowers in elongated spikes rather than rounded heads.

Typical varieties include:

• ‘Alpha’: candy pink with a slight violet cast, flowering until September.
• ‘Natascha’: striking white-and-fuchsia striped flowers – ideal for eye-catching border edges.

Drummond’s phlox: a summer star for balconies and containers

Anyone without large borders does not have to go without phlox. Annual Drummond’s phlox remains compact at 20 to 40 centimetres, making it perfect for window boxes, bowls and smaller spaces.

It flowers continuously from late spring until the first frosts – with regular watering and feeding, it scarcely pauses at all.

• colours ranging from white, cream, salmon and pink to rich red and blue
• many bicoloured forms with star or ring markings at the flower centre
• ideal for colourful mixed plantings on patios and balconies

How to plant phlox successfully in March

Phlox is considered straightforward to grow, but it particularly appreciates certain conditions. Meeting these requirements helps prevent disappointment in summer.

• Choose a position: full sun to light partial shade. In full sun, flowering is especially plentiful, provided the soil does not dry out.
• Prepare the soil: loosen it deeply and work in plenty of compost or well-rotted farmyard manure. Soil should be nutrient-rich, humus-rich and free-draining.
• Allow the right spacing: leave 30 to 40 centimetres between plants. This ensures sufficient air circulation around the shoots, helping to prevent fungal diseases.
• Plant correctly: water the root ball thoroughly, set it no deeper than it was in its pot, then gently firm the soil.
• Water in: water generously after planting and do not allow plants to dry out during the first few weeks.

Careful planting in March prevents many later problems with weak growth or powdery mildew.

Where phlox looks best in the garden

This perennial can be used in surprisingly versatile ways. With a few simple approaches, borders can quickly be turned from a “well-behaved strip” into a colourful stage.

• In a perennial border: combined with asters, coneflowers, delphiniums and old rose varieties, phlox creates a classic cottage-garden look.
• As a background plant: tall phlox varieties can conceal fences, old walls or plain wire fencing.
• In containers: annual phlox varieties make window boxes overflow and combine well with geraniums or verbenas.
• As a cut flower: garden phlox lasts surprisingly well in a vase and releases a pleasant fragrance.

Care: little effort, great effect

Anyone taking a quick look through the border every two or three days will find phlox needs very little attention. A few tasks are nevertheless worthwhile:

• Regularly cut out faded stems to encourage fresh buds.
• During hot spells, water thoroughly in the morning or evening, preferably close to the soil.
• Feed lightly once in spring and again in early summer, using an organic general fertiliser or compost, for example.
• Divide and replant perennial clumps every few years to keep the plants vigorous.

One issue that puts many people off is powdery mildew. Phlox is more sensitive when air is stagnant and humid, or when nutrients are lacking. An airy position, the planting distances mentioned above and soil that does not become too dry all reduce the risk considerably. Those who wish can also use established garden treatments such as sulphur-based products, or choose varieties regarded as robust.

Why phlox is particularly worthwhile for lazy gardeners

Many people with limited time want plants that deliver a “wow factor” without requiring constant care. This is exactly where phlox excels: once planted, it returns reliably every year, rapidly develops into dense clumps and decorates the garden for weeks.

For beginners, a combination of two or three tall varieties in different colours, plus several annual plants in pots, is worthwhile. This makes it easy to discover which colour scheme is most appealing – from romantic pink and white to bold pink, red and violet.

Phlox is also an excellent choice for anyone seeking insect-friendly plants: its fragrant flowers attract butterflies, solitary bees and other pollinators. At a time when summer food sources are scarce, this is a genuine benefit for biodiversity in the home garden.

A “phlox ribbon” repeated throughout the garden can also be effective: use the same variety beside the seating area, along a path and again at the back of the garden. Even small gardens then appear considerably larger and more harmonious – all through a single plant group started in March.