Ipomoea Heavenly Blue

Ipomoea purpurea 'Heavenly Blue' Morning Glory 'Heavenly Blue'

The truest blue in the climbing garden — massive azure trumpet flowers, 8–10cm across, with crisp white throats, opening fresh every morning on vigorous vines that reach 3 metres or more in a single season. 'Heavenly Blue' holds the RHS Award of Garden Merit and is one of the most genuinely sky-blue flowers in cultivation.

There are very few flowers in the entire plant kingdom that achieve true sky blue — most "blue" flowers lean toward violet, lavender or indigo. 'Heavenly Blue' achieves the real thing: a pure clear azure that genuinely resembles a cloudless summer sky, made even more striking by the crisp white throat at the centre of each large 8–10cm trumpet. The vines grow vigorously (3m or more in a single UK summer), twining clockwise around any support — trellis, pergola, fence, or even strings — to create a dense curtain of heart-shaped foliage punctuated daily by the spectacular blue flowers. Each individual flower opens at dawn and closes by mid-afternoon (hence the common name), but new flowers open every day from July through to the first autumn frosts, providing months of continuous display. Half-hardy annual. Holds the RHS Award of Garden Merit.

A note on growing

Morning Glory has two specific growing requirements that catch out many gardeners:

1. Soak the seeds before sowing. The seed coat is unusually hard and impermeable. Soak overnight (24 hours) in warm water before sowing — this dramatically improves germination rate and speed. Some gardeners also nick the seed coat gently with sandpaper or a knife (this is called "scarification") for even faster germination.

2. Wait for genuine warmth. Ipomoea is properly frost-tender and resents cold soil. Sow indoors April–May at 20–22°C, or direct outdoors only after late May or June when soil has warmed thoroughly. Germination 7–14 days after soaking. Plant out only after all risk of frost has passed.

Plant in full sun against a sturdy support — trellis, wires, netting, or strings. Rich, moisture-retentive but well-drained soil. Once established, water during dry spells but avoid waterlogged conditions. The vines need climbing support from the very beginning — they cannot self-support and will sprawl across the ground without it.

⚠️ Toxicity warning: Ipomoea seeds contain LSA (lysergic acid amide) and are toxic if ingested. Keep packets away from children and pets. Wear gloves when handling.

Where it shines

Against sunny walls and fences, where the vigorous growth covers vertical surfaces in a single season. Over pergolas, archways and trellises for proper architectural drama. In containers with a tall trellis or wigwam support — Morning Glory adapts well to large pots provided the soil doesn't dry out. As a fast-growing screen for unsightly fences or storage areas. As a daily early-morning visual treat — the flowers are at their most beautiful in cool morning light, and the daily opening becomes a small ritual through summer.

Plant alongside

For pure colour drama, pair 'Heavenly Blue' with Cobaea scandens 'Purple' (another climbing annual; matching height and habit, complementary purple) for a striking blue-and-purple wall covering. For an evening-and-morning scheme, combine with night-scented Moonflower (Ipomoea alba, if stocked) — Heavenly Blue opens at dawn as Moonflower closes; Moonflower opens at dusk as Heavenly Blue closes. With Sweet Peas at the base for fragrance contrast against the unscented Morning Glory.