Promise Sweet Pea Plants

• Variety: Promise
• Type: Spencer
• Colour: Soft lilac-pink
• Scent: 3/5 (Parsons) – clean and sweet
• Flowers: Medium-large, gently waved. 3–4 per stem
• Stems: Good length and straight – reliable for cutting
• Height: 1.8–2m (6–7ft) with support
• Flowering: 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

Promise – Gentle Colour, Strong Habit

There are sweet pea varieties that demand attention and varieties that earn it gradually. Promise belongs firmly in the second camp. The flowers are a soft lilac-pink – closer to the inside of a seashell than to anything you would find in a paint chart – with a delicacy that belies the vigour of the plant beneath. The colour is quiet, restful, and surprisingly versatile. It works in a pastel scheme without vanishing. It works alongside deeper tones without clashing.

The flowers are gently waved rather than heavily ruffled, medium-large, and carried on straight stems of good cutting length. Three to four per stem is typical. The plant reaches 1.8–2m (6–7ft) with support and has a strong, determined habit – it climbs well, branches willingly, and flowers freely over a long season. Unwins bred it, and it has the dependability you expect from their introductions: no drama, no fuss, just consistent performance from the first flowers in June to the last in September.

A Mixer's Colour

Lilac-pink is one of the more useful colours in a sweet pea display. Pure pink can dominate a bunch. Pure lilac can look cold. Promise sits between the two, warm enough to read as pink in evening light, cool enough to hold its own among blues and mauves in full sun. The colour lightens as each bloom ages, so a stem in water carries a gentle progression from deeper lilac-pink at the top to almost white at the base.

Scent is clean and sweet – a 3 on the Parsons scale, which is honest Spencer-level fragrance. You will notice it from a bunch in a vase and catch it in the garden when you lean in to cut. For a stronger hit, mix Promise with one of the heavily scented Grandifloras and let the Grandiflora do the work on fragrance while Promise handles the visual.

Pairing Ideas

For a pastel scheme with depth, pair Promise with Anniversary (soft pink with a lavender edge) and Mrs Collier (primrose cream). The three together on a wigwam give a watercolour effect – soft, blended, romantic. For contrast, add Windsor (deep maroon) as a single dark accent.

In a cutting garden, Promise mixes well with late-summer dahlias – something pale and blowsy like Café au Lait or the softer tones of Crichton Honey. The sweet peas provide early-season cut flowers and by the time they fade, the dahlias take over. For growing and training advice, see our sweet pea growing guide.

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 Promise?

Soft lilac-pink – warmer than lavender, cooler than true pink. The colour lightens as each bloom ages, giving a stem in water a gentle gradation from deeper pink at the top to almost white below. In evening light, the pink warms; in full sun, the lilac comes forward.

How scented is Promise?

Clean and sweet – a 3 on the Parsons scale, which is standard Spencer-level fragrance. A bunch on a table is pleasant. In the garden, you catch it when you lean in. For a more powerful hit, grow Promise alongside a Grandiflora like King's High Scent.

Is Promise good for cutting?

Yes – straight stems, good length, and a gentle colour that mixes well in arrangements. Cut in the morning when the lowest bloom is opening and strip any leaves that would sit below the water. The soft lilac-pink complements almost any other colour in the vase.

Can I grow Promise in a pot?

Yes. A deep container with at least 4 litres of compost per plant. Do not let the pot dry out – water every morning in warm weather and feed with tomato feed once buds form. Our pots guide covers everything you need to know.

Do sweet peas come back every year?

No – annual. One season, then finished. Promise will flower from June to September and that is its lot. For the full range of annual sweet peas, including heavily scented heritage varieties, see our sweet pea collection.