Morning glory 'Heavenly Blue'

Sun

Full sun in a warm, sheltered position.

Water

Water regularly while establishing, then when the soil surface begins to dry. Containers need more frequent watering; avoid waterlogged soil.

Soil

Well-drained soil of moderate fertility; avoid very rich soil and heavy nitrogen feeding.

Height

6-12 ft (1.8-3.7 m)

Spread

3-6 ft (0.9-1.8 m), depending on support and training

Flowers

Summer to autumn frost; large sky-blue trumpets with white throats, sometimes opening later in cool regions.

Foliage

Green, heart-shaped leaves on slender twining stems.

Growth

Fast in warm weather

Care needed

Low

• Pollinators
• Heat tolerant
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   2 ft (0.6 m)

2. After 1 year

   3 ft (1.1 m)

3. After 2 years

   5 ft (1.5 m)

4. After 3 years

   6 ft (1.8 m)

   full size

About 3 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Plant outside only after frost danger has passed and the soil has warmed.
• Provide a trellis, netting or vertical strings at planting; guide young stems onto the support.
• Water at soil level when the surface begins to dry, keeping young plants evenly moist.
• Use little fertilizer in garden soil; feed container plants lightly with a low-nitrogen flowering-plant fertilizer.
• Apply a thin mulch after the soil warms, keeping it clear of the stems.

Pruning. Pinch young shoot tips if you want bushier growth, and redirect or trim wayward stems during summer. Remove the whole plant after frost kills it, or earlier before seed ripens if self-seeding is unwanted.

Early spring

In short-season climates, sow indoors about four to six weeks before the last frost, using individual pots to limit root disturbance.

Late spring

Harden off seedlings and plant out after frost danger has passed; alternatively, sow directly into warm soil.

Early summer

Guide stems onto strings or a trellis and water regularly while roots establish.

Summer

Check container moisture frequently and keep vigorous shoots away from neighbouring plants.

Autumn

Remove seed capsules before they ripen if you do not want seedlings.

Late autumn

After frost, clear dead vines from supports. In frost-free climates, remove plants when flowering declines.

• Train over a sunny arch or obelisk for a temporary vertical accent.
• Grow up balcony strings or a container trellis for a seasonal leafy screen.
• Cover a sunny fence with blue flowers, pairing it with white cosmos or pink zinnias below.
• Use on a separate support at the back of a border so its stems do not smother smaller plants.

Garden styles it suits: Cottage garden, Romantic rose garden, Traditional, Modern courtyard, Tropical and Small-space.

Plant it with: Cosmos, Zinnia, French marigold, Salvia and Verbena.

Wildlife: Flowers attract bees and, where present, hummingbirds. It is not a substitute for locally native host plants.

• Lots of leaves but few flowers: reduce nitrogen feeding and provide full sun; cool weather and late seasonal flowering can also delay blooms.
• Spider mites in hot, dry conditions: inspect leaf undersides for stippling and fine webbing; rinse foliage thoroughly and use insecticidal soap if needed, following the label.
• Aphids on soft growth: wash off with water and encourage ladybirds and other predators.
• Yellowing and wilting in wet soil: improve drainage and let the surface dry between waterings; discard plants with rotting roots.

Treat as toxic to people, cats, dogs and horses, especially the seeds, which contain compounds that can cause vomiting, diarrhoea, disorientation and other neurological effects. Significant seed ingestion can be serious; keep seeds away from children and animals and seek medical or veterinary advice after ingestion. Do not eat any part.

Where it spreads. Can self-seed in warm parts of the southern United States and Australia, although it is generally less aggressive than blue dawn flower (Ipomoea indica). Regional weed records often use the broad name 'morning glory', so check the exact botanical name and local guidance before planting.

• Common morning glory (Ipomoea purpurea)

  Usually has noticeably hairy stems and leaves, with flowers in purple, pink, white or mixed colours. 'Heavenly Blue' has largely hairless growth and large blue flowers with white throats.

• Blue dawn flower (Ipomoea indica)

  A vigorous perennial in mild climates, often with hairy, three-lobed leaves and clusters of blue-purple flowers. It spreads readily from rooting stems and is a serious invasive plant in several regions.

• Field bindweed (Convolvulus arvensis)

  Has much smaller white or pale pink flowers and arrow-shaped leaves. It is a persistent perennial spreading through extensive underground roots.

Morning glory refers to the flowers opening in the morning, while 'Heavenly Blue' describes their clear sky-blue colour.

Propagation. Grow from seed. Lightly nick the seed coat away from the attachment scar, or soak seeds overnight, then sow about 0.25 in (6 mm) deep in warm compost or soil. Use individual pots for indoor sowing and transplant gently, as roots dislike disturbance.

Accepted botanical name

Ipomoea tricolor

In the US and Canada

Native in Puerto Rico. Introduced in the lower 48 states and US Virgin Islands.

Native range

Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Southeast and Mexico Southwest.

Measured

Average height 115 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.