How to Grow
Sweet Pea 'Leamington' from Seed
The gold standard lavender sweet pea — Hardy Annual H3; RHS AGM; classic Spencer type; rich lavender-lilac "crushed silk" deeply waved flowers; exceptionally long straight stems; typically 4 blooms per stem; sun-proof colour stability; exhibition bench standard; vigorous to 2.4m; sow Oct–Nov (best) in root trainers cold frame, or Jan–Mar at 15°C; TOXICITY: all parts mildly toxic
Sweet Pea 'Leamington' is the gold standard for lavender sweet peas — the variety against which every other lavender-coloured sweet pea is informally measured by exhibitors and cutting garden growers throughout the United Kingdom. As a classic Spencer type, it produces the large, deeply waved, frilly flowers on long, straight stems that define the Spencer ideal: rich lavender-lilac petals with the waved texture described as resembling crushed silk, typically bearing 4 blooms per stem on stems of exceptional length that are the exhibition sweet pea benchmark.
The RHS Award of Garden Merit confirms what decades of cultivation have demonstrated: Leamington is reliable, stable, and of outstanding quality for the ordinary UK home gardener, not only for exhibitors. The sun-proof colour quality — maintaining the clear lavender-lilac without fading or burning in summer sun — and the combination of strong fragrance, long stems, and consistent bloom count make Leamington the lavender sweet pea that rewards every investment of preparation and attention with one of the finest fragrant cutting garden performances available from a single variety.
Quick Facts at a Glance
Plant Type
Hardy Annual H3 — classic Spencer type; RHS AGM; the gold standard for lavender sweet peas
Colour
Rich lavender-lilac; deeply waved, frilly flowers "like crushed silk"; sun-proof colour
Stems
Exceptionally long, straight stems; typically 4 blooms per stem; exhibition standard
RHS AGM
Award of Garden Merit — confirmed reliable, superior performance for UK gardens
TOXICITY
All parts mildly toxic — do not eat; keep away from children and pets
Difficulty
2 out of 5 — a classic Spencer requiring the same care as all sweet peas; richly rewarding
Understanding Leamington
Toxicity Warning — All Parts Mildly Toxic
Sweet pea seeds and all parts of the plant are mildly toxic if ingested. They must not be eaten and should not be mistaken for edible garden peas, which they resemble closely in seed form. Keep seeds and plants away from children and pets at all stages.
The Gold Standard for Lavender Sweet Peas
Leamington is the lavender sweet pea against which all others are measured: large, deeply waved, frilly flowers in a rich lavender-lilac that is described as resembling crushed silk at peak development. As a Spencer type, Leamington produces the long, straight stems and four blooms per stem that make it an exhibition-standard variety — it has been a staple on the competitive sweet pea bench for decades precisely because the colour is clear and consistent, the stems are long, and the waved petals show the Spencer characteristic fully. The RHS Award of Garden Merit confirms its superiority not only for exhibitors but for ordinary garden performance in the UK climate.
Sun-Proof Colour — Holds Lavender Without Fading
Lavender and purple sweet peas can be prone to fading or "burning" in direct sunlight, particularly during the hot spells of a UK July and August. Leamington has specifically maintained its sun-proof reputation over its decades of cultivation: the clear lavender-lilac colour holds its intensity without bleaching or developing a washed-out quality in full summer sun. This quality is particularly valuable for exhibitors who need consistent colour at the show bench, and for cut flower use where the lavender tones need to hold across the 4–6 day vase life.
Sowing, Establishing, and the Golden Rule
Sow in root trainers or deep pots at 1cm depth. Soak seeds for a few hours first; nick any that do not swell. Autumn sowing (October–November, cold frame) gives the strongest plants and flowers from May. Spring sowing (January–March) at 15°C for summer flowers. Pinch out at 4 pairs of leaves for bushy multi-stemmed growth. Pick every 2–3 days — never allow seed pods to form. Feed fortnightly with high-potash fertiliser from first buds. Water at the base; mulch to protect roots from summer heat.
Sowing & Growing On
Sow Oct–Nov (best) or Jan–Mar at 15°C — Root Trainers — 1cm — Soak First — Plant Mar–Apr — Strong Support to 2.4m — Pick Every 2–3 Days
Sow in root trainers at 1cm after soaking seeds. Best: October–November cold frame for May flowers. Spring: January–March at 15°C. Plant March–April in rich deep soil with 2.4m strong support. Pinch at 4 pairs. Pick every 2–3 days. Feed fortnightly from first buds.
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Sow in root trainers or deep pots at 1cm depth after soaking seeds for a few hours. For autumn sowing (October–November), overwinter in a cold frame — the plants develop deep root systems through winter and emerge as the strongest, most productive specimens possible. For spring sowing, maintain a consistent 15°C — heat above this level significantly inhibits germination.
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Grow on in cool, bright conditions and plant out March–April (autumn) or April–May (spring). Leamington is a vigorous climber reaching 2.4m — prepare a deep, richly-manured planting trench and erect a strong support structure at least 2m tall (2.4m for maximum stem length) before or at planting. Space plants 20–25cm apart.
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Pinch out at 4 pairs of leaves and train stems to the support as they develop. The long, straight stems that make Leamington an exhibition standard variety develop best when trained to vertical canes or netting from the earliest stage. Regularly remove any tendrils attaching to neighbouring plants — Leamington's strength is its stems, and they develop best when guided upward rather than scrambling laterally.
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Pick every 2–3 days; feed fortnightly; water at the base; mulch generously. The combined effect of consistent picking (preventing seed pods), fortnightly high-potash feeding (providing flowering nutrition), deep base watering (maintaining root moisture), and mulching (protecting roots from heat) is a Leamington plant that produces its long-stemmed lavender-lilac flowers from May through September in a good season.
Growing On & Care
The Exhibition Standard
Leamington's reputation on the sweet pea show bench reflects specific qualities that exhibitors have valued for decades: the colour is consistent and clear (rich lavender-lilac without muddy tones); the stems are long and straight (typically bearing 4 blooms per stem, which is the exhibition ideal); the waved petals show the Spencer characteristic fully; and the sun-proof quality maintains colour consistency from the garden to the show bench without fading in transit. For gardeners who grow for exhibition, Leamington is a reliable staple; for gardeners who grow for the vase, these same qualities make it outstanding.
The Lavender Palette in the Garden
The rich lavender-lilac of Leamington provides a specific colour contribution in the garden that neither pink nor blue-purple sweet peas provide: a cool, clear, sophisticated mid-tone that works as a harmoniser between warm pinks and cooler blues, and as a contrast to cream and white. The Bishy description suggests pairing with Aquilegia Blue for a "shimmering lavender-blue" early-season combination, and with Cosmos Purity for the clean white contrast that makes the lavender appear even more vibrant. In a mixed sweet pea planting, Leamington provides the lavender element that ties the palette together.
As a Cut Flower
The long, straight stems of Leamington — typically bearing 4 flowers with further buds — make it one of the finest cutting garden sweet peas. Cut in the early morning when 2–3 flowers are open; re-cut at an angle under water. In a simple glass vase without other flowers, the lavender-lilac of Leamington and its sweet, traditional fragrance create one of the most classically English summer vase displays possible. In mixed arrangements, the lavender tones complement cream, white, salmon, and deeper purple sweet peas from the same season.
Cordon Training for Exhibition Quality
For the longest, straightest stems and maximum bloom count per stem, grow Leamington as a cordon: train each plant as a single-stemmed vine, removing all side shoots, and tie the main stem vertically to a tall cane at 15cm intervals as it grows. The cordon method concentrates the plant's energy into fewer, longer, more uniform stems with larger flowers — the exhibition growing technique. For domestic cut flower use, the more informal approach of allowing several stems per plant to develop produces generous quantities of long-stemmed lavender-lilac flowers without the intensive management that cordon training requires.
Heat Management in Summer
Leamington, like all Spencer sweet peas, is susceptible to heat stress. When soil temperatures rise above 25°C, root function is impaired and flower production slows or stops. The management strategy: water deeply at the base every 2–3 days; apply a thick mulch (8–10cm of garden compost or bark) around the base immediately after planting to insulate the root zone; and avoid overhead watering which encourages mildew without addressing root heat. These three actions together maintain productive flowering through July and August in most UK summers.
Pollinators
The rich lavender-lilac flowers of Leamington, combined with its strong traditional sweet pea fragrance, attract bumblebees and long-tongued solitary bees consistently throughout the flowering season. Sweet peas have evolved their specific fragrance and flower form partly to attract these pollinators — the open, accessible pea-flower structure and the directional fragrance signal together guide bees to the nectar resource effectively. A well-established wigwam of Leamington buzzes with bee activity on warm summer mornings.
Sowing & Season Calendar
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
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| Autumn sow (Oct–Nov; root trainers; cold frame) |
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| Spring sow (Jan–Mar; cool 15°C; deep pots) |
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| Plant out (Mar–May depending on sow date) |
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| Pick every 2–3 days (never allow seed pods) |
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Common Problems & Solutions
| Problem | Likely Cause | What to Do |
|---|---|---|
| Lavender colour fading in summer sun | Extended hot spell; plant stressed | Leamington's sun-proof reputation generally holds in normal UK conditions. In extreme heat, mulch deeply, water at the base, and ensure plants are not water-stressed. Pick flowers at their freshest before extended sun exposure. |
| Stems shorter than expected; fewer than 4 blooms per stem | Insufficient nutrition; not trained vertically | Feed fortnightly with high-potash fertiliser. For maximum stem length, train vertically to tall canes from the earliest stage, removing side shoots for cordon-style growing if exhibition quality is the goal. |
| Flowering stopping mid-summer | Seed pods forming; heat stress | Strip all seed pods immediately. Mulch, water deeply, and maintain fortnightly feeding. Leamington resumes flowering as conditions improve. |
| Mildew on leaves | Normal late-season occurrence; poor air circulation | Water at the base only. Ensure plants are not overcrowded. Accept some mildew in late August as normal — it does not significantly affect well-established plants. |
Plant Specifications
The crushed-silk lavender that has graced the exhibition bench and the cottage garden vase for generations — long-stemmed, sun-proof, and richly fragrant
Sow in root trainers at 1cm after soaking seeds. Best: October–November in a cold frame for May flowers. Spring: January–March at 15°C. Plant March–April in deep, richly-manured soil with 2m+ support. Pinch at 4 pairs of leaves. Pick every 2–3 days and feed fortnightly from first buds. Leamington produces its richly fragrant lavender-lilac flowers from May through September.
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