Petunia
Petunia x hybrida · Nightshade family (Solanaceae)
| Hardiness zones | 10 to 11 |
|---|---|
| Sun | full sun |
| Water | moderate |
| Life cycle | tender perennial (grown as an annual) |
| Frost | Half-hardy: takes a light frost |
| Soil pH | 6.0–7.0 |
| Spacing | 12 to 18 inches |
About Petunia
Petunias are classic summer bedding and container flowers with trumpet-shaped blooms in nearly every color, from tiny millifloras to big grandifloras and spreading types like 'Wave' that cover 3-4 feet. NC State notes the flowers give nectar to hummingbirds and butterflies. Calibrachoa (million bells) looks like a small petunia but is a different plant grown from cuttings; it is prone to iron deficiency and root disease (Kentucky Extension).
Grown as a summer annual almost everywhere; survives winter only in zones 10-11 (NC State).
When to plant
Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.
- Start seeds indoors: 8 to 10 weeks before the last frost
- Set out plants: up to 2 weeks after the last frost
Start seed indoors 8-10 weeks before planting out (Clemson); the tiny seed needs light to sprout and germinates at 72-75 F (NC State). Most gardeners buy plants and set them out after frost danger has passed, 12-18 inches apart.
Soil
Light, well-drained soil of medium fertility; petunias tolerate poor soil if it drains well but bloom poorly in heavy soil.
Use light, well-drained soil of medium fertility with pH 6.0-7.0; follow a soil test.
Feeding
- About a month after planting, then monthly through summer: balanced fertilizer such as 10-10-10. Clemson advises a balanced fertilizer monthly. Kentucky Extension feeds spreading types in beds every 3-4 weeks, and in containers weekly with a water-soluble fertilizer.
Wetting leaves and flowers when watering invites petal blight and gray mold; water at the soil.
Harvest
Blooms from late spring until frost. Deadhead large-flowered and double types, and cut leggy plants back by about half in midsummer to bring on new flowers (Clemson); many newer spreading types keep blooming without deadheading (Kentucky Extension).
Varieties (21)
| Variety | Type | Days | Notes |
|---|---|---|---|
| Daddy series | Grandiflora | ||
| Dreams series | Grandiflora | ||
| Limbo Violet | Grandiflora | Large violet flowers on a compact plant. | |
| Picobella series | Milliflora | Very small flowers, 1-1.5 in across (milliflora type). | |
| Celebrity series | Multiflora | ||
| Comanche | Multiflora | Red flowers. | |
| Madness series | Multiflora | ||
| Merlin Blue Morn | Multiflora | White centers that blend to velvety blue at the edges. | |
| Laura Bush | Old-fashioned (Petunia x violacea) | Fragrant violet flowers on a vigorous plant about 24 in tall and 36 in wide; reseeds. | |
| Bee's Knees | Spreading | Deep yellow flowers with darker veins, 2-2.5 in across, on mounding or trailing plants 8-10 in tall; tolerates heat and rain. | |
| Opera Supreme Pink Morn | Spreading | Iridescent pink flowers on vigorous trailing plants. | |
| Supertunia | Spreading | A spreading type grown from cuttings. | |
| Surfinia | Spreading | ||
| Easy Wave series | Spreading (Wave) | A spreading petunia series. | |
| Purple Wave | Spreading (Wave) | Low, ground-hugging purple petunia that spreads into a carpet of color. | |
| Wave Blue | Spreading (Wave) | Trailing plant with velvety dark blue 2-inch flowers. | |
| Wave Lavender | Spreading (Wave) | Trailing, ground-cover habit with lavender flowers. | |
| Evening Scentsation | Spreading multiflora | Indigo-blue flowers with a sweet scent strongest in the evening; 5-8 in tall and 30-35 in wide. | |
| Tidal Wave Cherry | Spreading/upright (Tidal Wave) | Cherry-colored flowers. | |
| Tidal Wave Red Velour | Spreading/upright (Tidal Wave) | Deep red flowers. | |
| Tidal Wave Silver | Spreading/upright (Tidal Wave) | Silvery white flowers with dark purple centers. |
Pests to watch for
Aphids, Flea beetles, Slugs, Brown garden snail, Thrips, Leafminers, Whiteflies, Tobacco budworm (geranium or petunia budworm)
Diseases and problems
Gray mold, Root rot, Mosaic viruses, Southern blight, Bacterial wilt, Hail and wind damage, Tobacco mosaic and tomato mosaic, Cucumber mosaic, Turnip mosaic
In the kitchen
Safety: NC State and the ASPCA list petunias as non-toxic.
Pets: Non-toxic to dogs, cats and horses (ASPCA)
Sources
Photo: Photo: Forest and Kim Starr, CC BY 3.0, via Wikimedia Commons (CC BY 3.0). Photo resized for the web.
Planting dates and advice are general guidance; check with your local Cooperative Extension office for your area.