Zinnia

Sun

Full sun, preferably at least 6–8 hours of direct sunlight daily.

Water

Water young plants regularly; once established, water deeply when the top of the soil dries. Avoid prolonged drought and waterlogged roots.

Soil

Well-drained soil of average fertility; improve heavy soil with compost and drainage rather than keeping it constantly wet.

Height

0.5-4 ft (0.15-1.2 m), depending on variety

Spread

0.5-1.5 ft (0.15-0.45 m), depending on variety

Flowers

Summer to the first frost; white, cream, yellow, orange, pink, red, purple and green, including bicolours. Flowers may be single, semi-double or double.

Foliage

Opposite, pointed oval leaves with a rough, slightly hairy surface; usually medium green.

Growth

Fast; often flowers about 8–12 weeks after sowing in warm conditions.

Care needed

Medium

• Plant out only after frost risk has passed and the soil has warmed.
• Space plants according to their mature width so air can move between them.
• Water at soil level early in the day rather than wetting the leaves.
• Add compost before planting; feed container plants with a balanced liquid fertiliser at the label rate.
• Apply a light organic mulch once the soil is warm, keeping it away from stems.
• Support tall varieties in exposed sites before their stems become heavy with flowers.

Pruning. Pinch out the growing tip when young plants have several pairs of leaves to encourage branching. During summer, cut spent flowers or harvest flowering stems just above a pair of leaves to encourage more blooms.

Early spring

If starting indoors, sow into individual modules about 4–6 weeks before your last expected frost; provide warmth and bright light.

Late spring

Harden off indoor-grown seedlings and plant out after frost, or sow directly into warm soil.

Early summer

Thin crowded seedlings, pinch young plants for branching and install supports for tall varieties.

Summer

Water during dry spells, harvest flowers regularly and check leaves for mildew.

Late summer

Leave a few healthy flower heads to dry if you want to collect seed.

Autumn

Remove plants after frost or when flowering finishes; discard diseased foliage rather than leaving it in the bed.

• Plant tall varieties in sunny mixed borders with salvias and ornamental grasses for strong summer colour.
• Grow in rows or blocks in a cutting garden for repeated flower harvesting.
• Use compact varieties in sunny containers and along the front of borders.
• Mix single-flowered varieties with cosmos and marigolds in pollinator-friendly annual beds.
• Edge vegetable beds with zinnias for flowers and visiting beneficial insects.

Garden styles it suits: Cottage garden, Potager (kitchen garden), Pollinator garden, Hot border, Farmhouse and Mexican hacienda.

Plant it with: Cosmos, French marigold, Mealycup sage, Globe amaranth, Sweet alyssum and Fountain grass.

Wildlife: Open-centred flowers provide nectar and pollen for bees and butterflies. Very double flowers may offer little accessible food; dry seed heads can attract seed-eating birds.

• Powdery mildew: choose resistant varieties, give plants full sun and generous spacing, and remove badly affected leaves.
• Bacterial leaf spot and fungal leaf spots: avoid overhead watering, remove affected material and rotate planting sites; discard severely infected plants.
• Slugs and snails on seedlings: protect young plants with barriers or wildlife-conscious slug controls and remove hiding places nearby.
• Poor growth or rotting roots in cold, wet soil: delay planting until conditions warm and improve drainage; replace badly rotted plants.

Not known to be toxic to cats, dogs, horses or people; no plant parts are recognised as poisonous. It is an ornamental plant rather than a food crop, and eating plant material may still cause mild stomach upset.

• Narrowleaf zinnia (Zinnia angustifolia)

  Has much narrower leaves, a generally low, spreading habit and smaller flowers than most Zinnia elegans.

• Garden cosmos (Cosmos bipinnatus)

  Has finely divided, feathery leaves and slender stems, unlike the broad, rough leaves and sturdier stems of zinnia.

Zinnia honours the German botanist Johann Gottfried Zinn, while elegans is Latin for elegant.

Propagation. Grow from seed, either sown directly after frost into warm soil or started indoors shortly beforehand. Transplant gently while seedlings are small. Saved seed from hybrids or mixed plantings may produce flowers unlike the parent plants.

Accepted botanical name

Zinnia elegans

In the US and Canada

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

Native range

Belize, El Salvador, Guatemala, Honduras, Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico Southeast, Mexico Southwest and Nicaragua.

Measured

Average height 65 cm.

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