How to Grow
Pansy Swiss Giant 'Ullswater' from Seed
The heritage deep cobalt-blue giant pansy -- flowers up to 6-8cm with characteristic commanding black blotch; seeds need DARKNESS to germinate (cover tray in drawer or cupboard -- opposite of most flowers); 15-20°C; 10-20 days; move to bright light immediately at emergence; pinch out growing tip for bushy plants; cool-season plant excelling in spring (April-June) and as an autumn planting surviving the UK winter to flower September through to May; edible flowers; outstanding window box and container plant
Pansy 'Swiss Giant Ullswater' is the deep blue pansy that carries the tradition of the Swiss Giant series -- large, ruffled, richly-coloured flowers on compact plants, developed in Switzerland in the early 20th century to produce the biggest, most striking pansy flowers available from seed. The Ullswater variety is named after the lake in the Lake District, and produces the rich, deep cobalt-blue flowers with the characteristic large black blotch that centres each bloom and gives the Swiss Giant series its distinctively bold, face-like appearance. At their best, the flowers are approximately 6-8cm across -- genuinely "giant" by pansy standards, held well above the compact foliage on stems long enough to make these attractive as miniature cut flowers for small vases and buttonholes.
The most important practical note for sowing Pansy seeds -- and one that surprises many gardeners who assume that light is generally needed for germination -- is that pansy seeds require darkness to germinate. Unlike the many flowers in this growing guide series that need light (Nicotiana, Penstemon, Phacelia, etc.), pansies need to be covered and kept in the dark until they emerge. Sow into a seed tray, keep moist, and keep out of the light until germination (10-20 days). Understanding this requirement and acting on it is the difference between reliable germination and frustrating failure.
Quick Facts at a Glance
Plant Type
Hardy Perennial grown as annual/biennial -- giant cobalt-blue flowers with black blotch
Flowers
Deep cobalt-blue with characteristic black face; one of the largest pansy flowers available
DARKNESS
Seeds need DARKNESS to germinate -- cover seed tray; opposite of most flowers
Cool-season
Best spring and autumn display; suffers in midsummer heat; edible flowers
Sow
Sow into tray, cover lightly; DARK until germination; 15-20°C; 10-20 days
Difficulty
2 out of 5 -- darkness requirement is critical; otherwise straightforward
Understanding the Swiss Giant
The Swiss Giant Series -- Heritage and Distinction
The Swiss Giant pansy series was bred in Switzerland in the early 20th century with a specific brief: to produce pansy flowers of the largest possible size with clear, unmixed colours and the characteristic dark central blotch that gives pansies their distinctive "face" quality. The Ullswater blue is one of the named single-colour cultivars in this series -- a specific, pure deep cobalt-blue with a pronounced black blotch that reads as a distinct, individual personality rather than a simple flower. The Swiss Giant series is consistently larger-flowered than most modern hybrid pansy series and retains the heritage character of the original cottage garden pansy.
Darkness for Germination -- The Critical Rule
The darkness requirement for pansy germination is genuine and specific. Unlike light-needing species (where even indirect ambient room light is sufficient), pansies need to be actively excluded from light. The practical method: after sowing into moist compost and covering lightly with compost or vermiculite, place the seed tray in a drawer, cupboard, or enclosed propagator with opaque cover. Check every few days without exposing to more light than necessary. As soon as the first seedlings emerge (typically 10-14 days at 15-20°C), immediately move to bright light -- etiolated (drawn up in darkness) seedlings are weak and leggy, so light exposure should begin as soon as germination starts.
Cool-Season Timing -- When Pansies Excel
Pansies are cool-season plants that perform best in spring (March-May) and autumn (September-November) and struggle in the heat of midsummer. In a typical UK summer, this means the spring-planted display is often at its best from April through June before declining in July-August heat; and the autumn planting (from a July-August sowing) produces its best display from September through to spring -- pansies are one of the few flowering bedding plants that survive UK winters and provide colour from September through to April of the following year with minimal management. For a continuous pansy display, plan two sowings: one in spring for summer flowering and one in July-August for autumn-winter-spring colour.
Sowing & Growing On
Sow into Seed Tray, Cover Lightly, DARK Until Germination -- 15-20°C -- 10-20 Days
Sow seeds onto moist compost in a seed tray, covering lightly with compost or vermiculite. Place in DARKNESS (drawer, cupboard, or covered propagator) at 15-20°C. Check every few days. At first sign of germination (10-20 days), immediately move to bright light. Prick out when 2-3 true leaves appear.
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Sow onto moist compost in a seed tray, covering seeds with 5mm of fine compost or vermiculite. The seeds are small but manageable. Press gently into the compost before covering. Place the seed tray in complete darkness at 15-20°C. A drawer, cardboard box over the tray, or solid-lid propagator all work effectively. Keep moist without waterlogging throughout.
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Check every 2-3 days; immediately move to bright light at the first sign of emergence. Germination 10-20 days at 15-20°C. The moment the first pale seedling tips appear, move the tray immediately to the brightest available light (windowsill or propagator) to prevent drawn, etiolated growth. Seedlings that have been in darkness for several days after germination will be weak -- preventable by daily monitoring.
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Prick out when 2-3 true leaves appear; pinch out the growing tip for bushy plants. Handle by the seed leaf. Pot into individual modules or 5cm pots. When 5-7cm tall, pinch out the growing tip to encourage branching and a compact, multi-flowering habit rather than a single central stem. Grow on in cool, bright conditions.
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Plant out in spring or autumn; deadhead for extended flowering. Pansies in UK gardens provide their best display in cool seasons. Deadhead spent flowers promptly to prevent seed set and redirect energy into new bud production. In midsummer, allow the plants to recover in cool shade or cut back lightly for autumn regrowth.
Growing On & Care
The Deep Blue in the Garden
The deep cobalt-blue of Ullswater with its black blotch is particularly striking in container plantings where the individual flower faces are visible at close range and the full intensity of the colour can be appreciated. At planting densities of 15-20cm apart, a container or window box of Ullswater in full flower in April-May provides one of the most richly-coloured cool-season container displays available from a UK seed packet. The depth of colour is maintained across the entire flowering season and does not fade significantly as the flowers age.
Spring and Autumn Display Timing
For the most rewarding display calendar: sow in February-March for spring flowering from April onwards (plant out in March-April); sow again in July-August for autumn-winter-spring flowering from September right through to the following spring (plant out in September). The July-August sown plants are the most versatile -- providing colour right through winter in sheltered positions and exploding into full display in February-April of the following year when every other colour in the garden is minimal. Winter pansies are one of the few reliable sources of genuine colour in the October-March window.
Edible Flowers
Pansy flowers are fully edible with a mild, slightly sweet and slightly grassy flavour. The vibrant deep-blue Ullswater flowers make striking edible garnishes: float individual flowers in champagne or sparkling water for celebration drinks; scatter petals over salads for colour; freeze individual flowers in ice cubes for summer drinks; press the flowers between paper for botanical cards and bookmarks. The edibility is particularly appealing with the visually dramatic Ullswater blue -- a single flower in a small glass of water on a table is a decoration that can then be eaten.
Container and Window Box Specialist
Ullswater is one of the finest single-colour window box plants available: the deep blue is visible from a distance (important for window boxes viewed from the street), the compact habit fits well without sprawling, and the long flowering season (particularly the autumn-winter planting) provides colour at a time when most containers are empty. Classic container combinations: Ullswater blue and white Alyssum; Ullswater blue and yellow winter-flowering Viola; Ullswater blue and silver-foliage Dusty Miller for a cool, sophisticated palette. In a window box that faces any direction except north, an autumn-planted Ullswater will flower from September through the following May.
Miniature Cut Flowers
The long stems of Swiss Giant pansies (longer than most bedding pansies) make them usable as miniature cut flowers for small vases, bud vases, and buttonholes. Cut when fully open, strip lower leaves, and condition for 2 hours in cold water. Vase life 5-7 days. In a small vintage jug with other spring flowers (Forget-me-not, Primrose, small Narcissus), a few stems of Ullswater provide the richest blue element in an early spring arrangement that costs nothing from the garden.
Winter Hardiness -- The Year-Round Pansy
Viola × wittrockiana is genuinely hardy in the UK (H5 -- surviving temperatures to -10°C) when planted in well-drained soil or containers. A well-grown autumn-planted Ullswater in a sheltered position will survive a typical UK winter with minor leaf damage but good crown protection, and resume flowering vigorously in February-March when temperatures rise. This winter hardiness is one of the most practical qualities of the pansy in the UK garden -- it is not a frost-tender summer annual but a genuinely winter-surviving bedding plant that provides October-to-May colour from a single autumn planting.
Sowing & Flowering Calendar
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| Spring sow (Feb-Apr) for spring/summer display |
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| Autumn sow (Jul-Aug) for autumn/winter/spring display |
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| Spring-summer flowers (Apr-Jun) |
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| Autumn-winter-spring flowers (Sep-May) |
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Common Problems & Solutions
| Problem | Likely Cause | What to Do |
|---|---|---|
| No germination; seeds not sprouting | Tray exposed to light; temperature too low | Pansy seeds need complete darkness and 15-20°C consistently. Any light exposure during germination significantly reduces or prevents sprouting. Place in a drawer, covered propagator, or under a cardboard box. Check temperature -- below 15°C produces very slow or failed germination. |
| Etiolated (drawn, pale, leggy) seedlings | Darkness continued after germination began | Move to bright light the moment the first seedlings are visible. Every extra day in darkness after germination produces progressively weaker, more drawn seedlings. Monitor daily from day 7 onwards. |
| Plants bolting in summer; display finishing early | Midsummer heat; not a cool-season problem | Pansies naturally struggle in UK midsummer heat. Cut back lightly in July-August for autumn recovery, or replace with heat-tolerant summer annuals and replant pansies in September for the autumn-winter-spring display. |
| Few flowers; compact but not flowering | Not deadheaded; tip not pinched | Pinch out the growing tip when plants are 5-7cm tall to encourage branching. Deadhead spent flowers regularly -- removing flowers before they set seed redirects energy into new bud production significantly extending the display. |
Plant Specifications
The deep cobalt-blue face that needs darkness to wake up -- sow covered, emerge into light, and flower from April to May the following year
Sow covered into moist compost and keep in complete darkness at 15-20°C. Check every 2-3 days. Move to bright light immediately at the first sign of germination (10-20 days). Pinch out the growing tip at 5-7cm for bushy plants. Plant in spring for April-June flowers or in July-August for the autumn-winter-spring display that survives every UK winter.
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