Highlights

Extraordinary Height – Grows up to 150cm (5ft), towering above standard petunias for dramatic vertical impact.
Fully Double Blooms – Large, lush flowers up to 12cm across provide vibrant colour and texture for over 5 months.
Continuous Flowering – Specially bred to re-flower from early summer into autumn, keeping displays fresh and full.
Low Maintenance – Male-sterile variety naturally drops spent blooms, so no deadheading required.
Outstanding Cut Flowers – Strong stems hold 20+ blooms per stem; lasts 7–10 days in a vase.
Mature Size – Height: 150cm (5ft); Spread: 75cm (30in).
Weather Resistant – Robust stems and modern breeding provide excellent garden performance.
Versatile Planting – Ideal for borders, patios, containers, and statement planting schemes.
Italian Heritage – Developed on Mount Vesuvius for Mediterranean flair and robust growth.
Plug Plants Supplied – Ready for potting now; includes 'Allegra Pastel Orchid', 'Allegra Picotee Velvet', and 'Allegra Pure White'.

We're offering you a Giant Petunia Mixed Collection for £5.99, saving you up to 40% off Thompson and Morgan's's price of £9.99 (correct as of 07.05.2026).

Transform Your Summer Garden with Giant Petunia 'Allegra F1'

Petunia 'Allegra F1', an Italian-bred breakthrough, brings unrivalled height and opulent double blooms to your outdoor space. Reaching up to 150cm (5ft) tall and spreading to 75cm (30in), this exceptional perennial delivers a spectacular vertical presence far beyond ordinary petunias.

Breathtaking Blooms: Each stem produces masses of fully double flowers up to 12cm across in pastel lavender, magenta-white bicolour, and pure white shades. Enjoy continuous colour from early summer through autumn.
No Fuss, All Beauty: This male-sterile variety naturally sheds spent blooms—so you spend less time deadheading and more time admiring your display.
Perfect Indoors & Out: Strong stems hold over 20 blooms per stem, making them a standout choice for long-lasting cut flower arrangements (7–10 days in water).
Mediterranean Heritage: Developed on the slopes of Mount Vesuvius, these petunias thrive in UK gardens with robust growth and outstanding weather resistance.

Growing Guide & Care Tips

Planting Time: Plant plug plants after the last frost—typically from late April through May.
Sun Requirements: Choose a spot in full sun for best flowering performance.
Soil Preferences: Prefers fertile, well-drained soil. Add organic matter before planting for extra vigour.
Irrigation: Water regularly during dry spells; avoid waterlogging.
Pests & Diseases: Generally pest resistant but watch for aphids or slugs in damp conditions.
No Deadheading Needed: Enjoy effortless maintenance thanks to self-cleaning blooms.

'Allegra Collection' Varieties Included

'Allegra Pastel Orchid': Soft lavender tones bring gentle elegance.
'Allegra Picotee Velvet': Striking magenta with white bicolour edges for bold contrast.
'Allegra Pure White': Crisp white blooms create a fresh, classic look.

Clever Design Ideas & Companion Plants

Create dramatic borders by pairing with upright salvias or ornamental grasses.
Add height and structure to patio containers alongside trailing lobelia or bacopa.
Makes a show-stopping centrepiece in mixed summer bedding schemes.

FAQs

When is the best time to plant these petunias?
The best time is after the last frost in spring—typically late April or May in the UK.
How tall do they really grow?
This variety can reach up to 150cm (5ft) when grown in ideal conditions with full sun and good soil.
Do I need to deadhead the flowers?
No—these petunias are male-sterile and naturally drop spent blooms, so maintenance is minimal!