Windsor Sweet Pea Plants

• Variety: Windsor
• Type: Spencer
• Colour: Deep maroon-crimson
• Scent: 3/5 (Parsons) — stronger than you'd expect from a dark variety
• Flowers: Medium-large, well-waved Spencer form. Typically 3–4 blooms per stem
• Stems: Good length and reasonably straight — reliable for cutting, though not quite exhibition-stiff
• Height: 2m (6–7ft) with support
• Flowering: Late June to September with regular picking
• RHS AGM: No
• Bred by: Unwins
• Sold as: Jumbo plug plants, hand-sown by us
• Plant outdoors: After last frost
• Delivered: March to May by next-day courier

Windsor – The Maroon Spencer

Talk about a picture being worth a thousand words. Here are sweet peas that need a paragraph of explanation but you understand them at a glance. The flowers are a deep, saturated maroon-crimson – the colour of old port, or a well-polished conker – and they hold that depth from when the buds open until the petals drop. No fading, no gradual drift towards muddy mauve. What you see on day one is what you get on day five.

Colour stability is worth mentioning because it is not universal among dark sweet peas. Many "lose their nerve "in strong sun and bleach at the edges. Windsor does not. If anything, full sun brings out a warm ruby undertone, while shade pushes the blooms closer to black. The same plant can look like two different varieties depending on the light.

Honest Colour in a Crowded Field

The dark sweet pea category has more contenders than it used to. Black Knight is the heritage option, Almost Black goes further into near-purple territory, and Heathcliff brings exhibition polish to the dark end of the spectrum. Well, Windsor sits squarely in the maroon camp – redder than Almost Black, warmer than Black Knight, and without Heathcliff's show-bench ambitions. Windsor is a garden variety in the best sense. It grows well, flowers freely, and provides a colour that is harder to find than you might think: a true, clean maroon without purple or blue muddying the tone.

Unwins bred it, though the exact date is not recorded. It has been in circulation long enough to have proved itself reliable, which matters more than a pedigree certificate.

Scent and Stems

Fragrance is moderate – around 3 on the Parsons scale. You notice it when you lean in, and a bunch in a small room is noticeable. It is not a variety you grow for perfume alone, but the scent is sweet. If you want a dark sweet pea with real scent power, grow Matucana alongside it – the two together give you depth of colour and fragrance.

Stems are good. Not the ramrod-straight exhibition stems of a Bristol or a Gwendoline, but long and straight enough to cut confidently. Three to four blooms per stem is typical, with decent spacing between them. They hold well in water.

Where Windsor Works Best

Dark sweet peas need pale neighbours. Grow Windsor on its own and it can vanish into its own shadows, especially against a dark fence or hedge. Put it next to Jilly (ivory-cream) or Mrs Collier (warm cream) and the maroon suddenly becomes electric. The pale flowers lift the dark ones; the dark flowers give the pale ones something to lean against. It is the oldest trick in the garden, and it works every time.

In the vase, the same principle applies. A jam jar of Windsor alone looks sombre. Add three stems of something cream or white and the arrangement comes alive. The maroon reads as richness rather than darkness when it has contrast to play off.

One thing to watch: Windsor's dark petals absorb heat in full sun. On very hot days – the kind we seem to get more often now – the flowers can go over faster than lighter varieties. Pick early in the morning on those days, and don't leave cut stems out of water even briefly.

Growing

Standard Spencer culture. Full sun, rich soil, support in place before planting. Space plants 10–15cm apart. Windsor is a reliable grower without being especially vigorous – it tends to put energy into flowering rather than rampant leaf growth, which is no bad thing.

In pots, allow 4 litres per plant and don't let the compost dry out. A high-potash feed every fortnight once buds appear keeps the flowers coming. Tomato feed works well and is easy to find but for full instructions see our sweet pea growing guide.

Oh - and keep cutting. Every pod you allow to set is a signal to the plant that its work is done.

Planting Companions

Windsor's maroon is at its best against cream, white, and soft blue. Jilly is the natural partner but for a cooler contrast, add Noel Sutton (mid-blue Spencer) or Bobby's Girl (shell-pink). The three together on a wigwam or obelisk give you a range that reads as considered rather than chaotic.

If you are planting a dark-themed display, pair with Heathcliff and Almost Black, but include at least one light variety to stop the whole thing disappearing. Or just do what we do at home - plant it with every other sweet pea we can find and produce a riot of colour and a scent powerhouse that fills the garden and supplies masses of flowers every day of the week for most of the summer.

Why Buy Your Sweet Pea Seedlings from Ashridge?

We have been growing sweet peas in Somerset since the early 2000s. The seed - which we collect - is hand-sown at two seeds per plug and the weaker seedling is removed. Every plant is then pinched out to encourage bushy growth and hardened off before dispatch. What you are buying are sturdy, garden-ready jumbo plug plants that have had the best possible start.

We send your sweet peas out by next-day courier between March and May, packed in purpose-designed recycled cardboard packaging. The moment they arrive, they are ready to go into the ground or a container. If anything is not right, we have real people on the phone in Somerset who will sort it out. We hold a Feefo Platinum Service Award and have been named a Which? Best Buy plant supplier — endorsements that came from our customers, not our marketing team.

Frequently Asked Questions

What colour is Windsor?

A deep maroon-crimson – think dark red wine or polished mahogany. The tone shifts with the light: warmer and more ruby in direct sun, darker and almost black in shade. Unlike some dark sweet peas, it holds its colour well and does not bleach or fade to mauve as the blooms age.

How fragrant is Windsor?

Better than you might expect from a dark Spencer. The scent is sweet and clean — not powerful enough to fill a room, but a handful of stems beside the bed is noticeable the following morning. Dark-flowered varieties are often weak on fragrance; Windsor bucks that trend.

Can I grow Windsor in a pot?

Yes — and the dark flowers look striking against a pale wall or stone terrace. Give the roots plenty of depth and volume, keep the compost consistently damp, and feed regularly once flowering starts. A large pot with an obelisk by a seating area puts the colour and scent where you can enjoy them.

Do sweet peas come back every year?

No. Sweet peas (Lathyrus odoratus) are annuals – they complete their lifecycle in one season and will not return the following year. The perennial pea (Lathyrus latifolius) does come back, but it is scentless and limited to pink, white, or magenta. Annual sweet peas give you the colour range, the fragrance, and the cutting stems — at the cost of replanting each spring. Browse our sweet pea collection from late winter for next year's plants.

Are sweet peas safe around pets?

The seeds and pods contain lathyrin, which can cause problems if eaten in quantity. The flowers and foliage are not usually an issue, but keep seed pods away from curious dogs and young children. If your dog is a dedicated chewer, site the plants where they cannot reach the lower stems.