'Turquoise Lagoon' Sweet Pea Plants

• Variety: Turquoise Lagoon
• Type: Lathyrus × hammettii hybrid
• Colour: Blue-green, the closest to turquoise in sweet peas
• Scent: Medium to strong. Complex and distinctive
• Flowers: Open-faced, lightly waved. 3–4 per stem, compact and vivid
• Stems: Shorter than a Spencer but strong enough for small arrangements
• Height: 1.2–1.5m (4–5ft) with support
• Flowering: June to September with regular picking
• RHS AGM: No
• Show class: L. × hammettii hybrid — not classified by NSPS
• Bred by: Dr Keith Hammett (New Zealand)
• Sold as: Jumbo plug plants, hand-sown by us
• Plant outdoors: After last frost
• Delivered: March to May by next-day courier. Collection from Castle Cary also available

Turquoise Lagoon – The Closest Thing to Blue

Turquoise Lagoon is not a conventional sweet pea but a Lathyrus × hammettii hybrid, a cross between the garden sweet pea (L. odoratus) and its wild Turkish relative L. belinensis. Dr Keith Hammett made the cross in New Zealand, and the result is a flower colour that does not exist anywhere else in the sweet pea world: a genuine blue-green, closer to turquoise than anything you will find in a seed catalogue. No Spencer, no Grandiflora, no heritage variety comes close. The colour alone is reason enough to grow it.

The plant is shorter than a standard Spencer, topping out at about 1.2–1.5m rather than the usual 2m. The flowers are smaller, open-faced, and lightly waved, with 3–4 blooms per stem. The scent is medium to strong and distinctly different from a typical sweet pea fragrance, with a sharper, more complex note inherited from the belinensis parent. Dr Hammett is probably the greatest living sweet pea breeder, and Turquoise Lagoon is one of his most original achievements. Unlike anything else in our collection.

Growing Turquoise Lagoon

The hammettii background means Turquoise Lagoon behaves differently from a standard variety: shorter, more compact, and less vigorous than a Spencer. That is not a weakness. It means Turquoise Lagoon works where tall sweet peas do not: in large containers on a patio, on a short obelisk in a border, or at the front of a planting where a 2m Spencer would be out of scale. A 1.2m hazel wigwam or a compact metal obelisk suits it perfectly.

Water consistently and feed fortnightly with a high-potash liquid feed once buds appear. Turquoise Lagoon is a little less forgiving of drought than a Spencer, partly because of the shorter root run and partly because the hammettii genetics prefer even moisture. In a container, this means daily watering in warm weather and never letting the compost dry out completely. For full growing and care guidance, see our sweet pea growing guide and for container-specific advice, our guide to growing sweet peas in pots.

One important point: seed saved from Turquoise Lagoon will not come true. The hammettii genetics are unstable and offspring vary widely. If you want Turquoise Lagoon again next year, buy fresh plugs.

Planting Companions for Turquoise Lagoon

The blue-green colour works alongside warm tones especially well. Promise (salmon-orange Spencer) makes a striking contrast, the warm salmon against the cool turquoise. Valerie Harrod (deep wine-crimson Spencer, AGM) provides depth and richness, with the turquoise lifting the darker colour. Erewhon (lavender-and-mauve bicolour) is the other hammettii hybrid in our collection, shorter than a Spencer and with a similarly complex scent, so the two share a support easily without one outgrowing the other.

In a garden setting, Turquoise Lagoon at the feet of a silver birch or weeping pear provides a lovely contrast: dappled light and a pale trunk for the blue-green flowers to glow against. The compact habit means it does not compete with the tree's lower branches.

What Makes Ashridge Sweet Peas Different?

Sweet peas have been part of the Ashridge range for over twenty years. The seed, which we collect ourselves, is hand-sown at two seeds per plug. After germination, 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.

Your sweet peas arrive by next-day courier between March and May, packed in purpose-designed recycled cardboard packaging. They are ready to plant the moment they arrive. 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 are a Which? Best Buy plant supplier, earned from customer recommendation.

Frequently Asked Questions

What makes Turquoise Lagoon different from other sweet peas?

Turquoise Lagoon is a Lathyrus × hammettii hybrid, a cross between the standard sweet pea and a wild Turkish species. This gives it a blue-green colour that no conventional variety can produce, a shorter, more compact habit (1.2–1.5m vs the usual 2m), and a distinctly different scent profile. The NSPS does not classify it because the variety falls outside standard sweet pea categories.

Can I grow Turquoise Lagoon in a pot?

Turquoise Lagoon is one of the best sweet peas for container growing. The compact habit (1.2–1.5m) means it does not outgrow a patio-sized support, and it flowers freely without needing the height that Spencers demand. Use a pot of at least 4 litres per plant with good drainage, water daily in warm weather, and feed fortnightly with tomato feed once buds appear. See our guide to growing sweet peas in pots for full container advice.

Can you smell Turquoise Lagoon in a room?

From a generous bunch, yes. The scent is medium to strong and distinctly different from a standard sweet pea fragrance, with a sharper, more complex note inherited from the L. belinensis parent. It is unusual and interesting rather than conventionally sweet. The English Sweet Peas guide rates it 5 out of 5 for fragrance; the Parsons rating is a more conservative 3.

Will saved seed come true?

Seed saved from Turquoise Lagoon will not come true. The hammettii genetics are unstable, and offspring will vary widely in colour, habit, and flower form. Some may revert towards one or other parent species. If you want the same blue-green flowers next year, buy fresh plugs rather than relying on saved seed.

Is Turquoise Lagoon an annual?

All sweet peas, including the hammettii hybrids, are annuals. Turquoise Lagoon gives you one season of that extraordinary blue-green colour from June to September, then it is finished. At the end of the season, cut stems at ground level and leave the roots in the soil. For fresh plants next spring, our sweet pea collection has Turquoise Lagoon alongside over thirty other named varieties.