May is a prime time for herbaceous perennials to take centre stage. From structural alliums to frothy tiarellas, there’s something for every garden spot and style — sun-drenched borders, shaded corners, or overflowing pots.
Here are some standout varieties to explore this month:
Alliums like ‘Purple Sensation’ and ‘Mount Everest’ bring bold architectural structure to borders in May. Their large, globe-shaped flower heads sit proudly atop tall, upright stems and are loved by pollinators. Best in full sun and well-drained soil, they add real drama to mixed planting schemes.
Flowers: May – June
Position: Full sun
Height: Up to 1.2m (depending on variety)
Soil: Fertile, well-drained soil
Pot size: 2L, 3L, 5L (depending on variety and subject to availability)
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Ajuga reptans ‘Catlin’s Giant’ is a low-growing groundcover that shines in spring with bold foliage and short spikes of deep blue flowers. Great for shady areas or under shrubs, it suppresses weeds and spreads gently over time.
Flowers: April – May (depending on the variety)
Position: Full sun – partial shade
Height: Up to 0.45m (depending on variety)
Soil: Moist, well-drained soil
Pot size: 2L, 3L (depending on variety and subject to availability)
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Astilbe ‘Fanal’ is a standout for part-shade borders, producing feathery red plumes above dark green foliage. It thrives in moisture-retentive, humus-rich soil and brings texture and colour to damp, shady corners from late spring.
Flowers: May – June, August (depends on the variety
Position: Full sun -partial shade
Height: Up to 1m (depending on variety)
Soil: Moist, humus, rich soil
Pot size: 2L, 5L (depending on variety and subject to availability)
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Brunnera macrophylla ‘Jack Frost’ has heart-shaped silver leaves and tiny blue flowers in spring, like a shimmering version of forget-me-nots. It’s perfect for shady borders and woodland gardens, adding elegance long after the blooms fade.
Flowers: April – May
Position: Partial shade
Height: Up to 0.4m depending on the variety
Soil: Fertile, humus-rich, moist, well-drained soil
Pot size: 2L, 3L (subject to availability and the variety)
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Also known as bleeding heart, Dicentra varieties produce romantic, heart-shaped flowers in spring above finely cut foliage. They love cool, shady spots and bring softness and nostalgia to cottage-style planting.
Flowers: April – May
Position: Full sun or partial shade
Soil: Moist, humus-rich, preferably neutral to slightly alkaline
Pot size: Available in 2L and 3L pots subject to availability.
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Erigeron karvinskianus and ‘Sea Breeze’ flower for months from May, with daisy-like blooms that fade from white to pink. They’re perfect for softening edges, trailing through walls, or filling gaps between paving stones.
Flowers: May – October (depending on variety)
Position: Full sun
Height: Up to 0.5m (depending on variety)
Soil: Fertile, well drained soil
Pot size: 2L
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Erysimum ‘Bowles’s Mauve’ is a long-flowering perennial with rich purple blooms that start as early as February and go well into summer. Great for sunny borders and loved by pollinators, it’s a must for low-maintenance planting.
Flowers: February – July
Position: Full sun
Soil: Fertile, well-drained, neutral soil
Pot size: Available in 2L pots subject to availability.
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This bold euphorbia makes a real statement with huge lime-green flower heads in spring, perched above bluish-green foliage. It thrives in full sun and is ideal for adding contrast and structure to sunny borders.
Available in 2L pots subject to availability.
Flowers: Late March-May
Position: Full sun
Pot size: Available in 2L pots subject to availability.
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Geums like ‘Totally Tangerine’ and ‘Cosmopolitan’ provide a long run of warm-toned blooms from May into summer. Their upright stems make them perfect for weaving through other perennials in sun-filled borders.
Flowers: May – August (depending on variety)
Position: Full sun
Height: Up to 0.6m (depending on variety)
Soil: Fertile, moist, well-drained soil
Pot size: 3L
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Hardy geraniums like ‘Rozanne’ and ‘Max Frei’ are garden workhorses, offering months of bloom from May onward. Their low-growing habit and wide colour range make them excellent for groundcover and border edging.
Flowers: May- October (depending on variety)
Position: Full sun – partial shade
Height: Up to 0.6m (depending on variety)
Soil: Fertile, well-drained soil
Pot size: 2L
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Tall and elegant, irises such as ‘Perry’s Blue’ and Iris pseudacorus bloom in May with striking flowers atop sword-like leaves. They thrive in full sun and work beautifully in water-adjacent or boggy garden spots.
Flowers: May-June
Position: Full sun
Height: Up to 1.2m (depending on variety)
Soil: Well-drained, moderately fertile, neutral to slightly acidic soil
Pot size: 2l, 3L (depending on variety and subject to availability).
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Lupins like ‘Gladiator’ and ‘Red Rum’ create dramatic vertical interest with their towering flower spikes. Loved in cottage gardens, they do best in sunny spots with well-drained soil and benefit from deadheading.
Flowers: June – July
Position: Full sun- partial shade
Height: Up to 1.2m (depending on variety)
Soil: Well-drained soil
Pot size: 2l, 3L, 5L (depending on variety and subject to availability).
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Tiarella, or foamflower, brings airy spikes of pale blooms to shaded areas in late spring. Its patterned foliage adds interest even when not in flower, making it perfect for woodland borders or underplanting.
Flowers: May – July
Position: Partial shade
Height: Up to 0.4m (depending on variety)
Soil: Cool, moist, humus-rich soil
Pot size: 3L (depending on variety and subject to availability)
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‘Sweet Kate’ stands out with vivid blue flowers and bold golden foliage. This compact perennial blooms from May and is great for brightening up partially shaded beds or containers with rich, moist soil.
Flowers: May – July
Position: Full sun – Partial shade
Height: Up to 0.3m (depending on variety)
Soil: Fertile, moist but well-drained soil
Pot size: 2L (depending on variety and subject to availability)
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Please note the above plants listed are subject to availability and is not an exhaustive list of what is available, please contact your sales rep direct for specific requests.
Posted 18th May 3:01pm
