Petunia

Sun

Full sun, ideally at least six hours daily. Light afternoon shade can help in very hot climates, but too much shade reduces flowering.

Water

Water thoroughly when the soil surface starts to dry, then let excess water drain away. Containers may need daily watering in hot or windy weather; avoid keeping the roots constantly wet.

Soil

Well-drained, moderately fertile soil. Use a good-quality container potting mix in pots and baskets; avoid waterlogged ground.

Height

0.5-1.5 ft (0.15-0.45 m)

Spread

1-4 ft (0.3-1.2 m), depending on the variety

Flowers

Late spring to autumn, often until frost; white, pink, red, purple, blue-purple, yellow and near-black, with striped, veined and bicoloured forms. Flowering may slow during extreme heat.

Foliage

Evergreen. Soft, green, oval leaves and branching stems, usually covered with fine, slightly sticky hairs. Leaves can persist through winter in frost-free conditions.

Growth

Fast

Care needed

Medium

• Plant outside after frost risk has passed, and allow space for the variety's mature spread.
• Water at soil level, soaking the root ball rather than repeatedly sprinkling the surface.
• Feed container plants with a flowering-plant fertiliser every one to two weeks, following the label rate.
• Check hanging baskets frequently in hot weather; a dry root ball can be difficult to rewet.
• Keep drainage holes clear and remove fallen flowers and dead leaves before they decay.

Pruning. Pinch young, leggy shoots to encourage branching. During the flowering season, remove spent blooms from large-flowered varieties and shorten straggly stems by about one-third; many modern trailing varieties shed their flowers without deadheading.

Early spring

Sow seed indoors in warmth and bright light, about 8-10 weeks before your last expected frost; press onto the surface without burying.

Spring

Pot on seedlings and gradually acclimatise indoor-grown plants to outdoor conditions.

Late spring

Plant out after frost risk has passed, water thoroughly and begin regular container feeding once plants are growing.

Early summer

Pinch straggly growth and start removing spent flowers where needed.

Summer

Check containers frequently for drying, feed regularly and trim tired stems to encourage fresh growth.

Autumn

Remove plants killed by frost. If you want to keep a favourite variety, take cuttings while growth is still healthy and overwinter them in bright, frost-free conditions.

• Trail over hanging baskets and window boxes for a curtain of summer flowers.
• Edge sunny borders with compact varieties to create a continuous ribbon of colour.
• Combine with verbena and sweet alyssum in patio containers for contrasting flower shapes.
• Plant a single colour in repeated pots beside a path or terrace for a simple, coordinated display.
• Use white or pale varieties near seating areas where their flowers remain visible into the evening.

Garden styles it suits: Cottage garden, Traditional, Modern courtyard, Small-space, Pastel border and White garden.

Plant it with: Verbena, Sweet alyssum, Pelargonium, Lobelia, French marigold and Dusty miller.

Wildlife: Single, open flowers can provide nectar for butterflies and moths, and some attract bees or hummingbirds where these occur. Fragrance and wildlife value vary between varieties; double flowers are generally less accessible.

• Aphids cluster on soft shoots and buds: wash them off with water or use insecticidal soap according to the label, avoiding open flowers and visiting insects.
• Slugs and snails eat seedlings and soft growth: inspect after dark, remove hiding places and use an approved iron-phosphate bait if necessary.
• Grey mould develops on damaged flowers in damp, crowded conditions: remove affected material, improve airflow and avoid wetting flowers when watering.
• Root rot causes wilting and yellowing despite wet soil: improve drainage, reduce watering and discard badly affected plants; never leave pots standing in water.

Petunias are not known to be toxic to cats, dogs, horses or people, and no plant part is recognised as poisonous. They are ornamental plants rather than food; eating a large amount may still cause digestive upset.

• Million bells (Calibrachoa)

  Usually has smaller flowers and narrower, smaller leaves on densely branching, often wiry trailing stems. Small-flowered petunias can be difficult to distinguish without a label.

• Flowering tobacco (Nicotiana alata)

  Has larger leaves and upright clusters of flowers with long, narrow tubes ending in star-shaped lobes, rather than the broad, open trumpets typical of petunias.

Petunia comes from the French word pétun, an old name for tobacco derived from a Tupi word, reflecting the plants' botanical relationship.

Propagation. Grow from seed in warmth and light, leaving the tiny seeds uncovered. Take non-flowering tip cuttings in late summer to preserve a particular variety; seed collected from hybrids may produce different plants, and some varieties set little or no viable seed.

Accepted botanical name

Petunia atkinsiana

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