Petunia

A prolific annual bedding plant with trumpet-shaped flowers in nearly every color, perfect for containers and borders. Petunias prefer full sun and well-drained soil, and benefit from regular feeding with a balanced liquid fertilizer every two weeks during the growing season. Deadhead spent blooms and cut back leggy stems by half in midsummer to stimulate a fresh flush of flowers. Spreading and trailing types are excellent for hanging baskets and window boxes, while grandiflora varieties produce the largest individual blooms.

Petunia seeds are dust-like and require light for germination. Sow on the surface of moist, fine seed-starting mix ten to twelve weeks before the last frost. Do not cover with soil. Mist gently and cover trays with clear plastic to maintain humidity. Seeds germinate in seven to ten days at 70 to 75 degrees Fahrenheit. Transplant seedlings into individual pots when they develop two true leaves. Pinch the growing tip when seedlings have six to eight leaves to encourage branching. Harden off before transplanting outdoors after the last frost.

The Season Plate

Your Petunia Year

Composed for Zone 7 · typical seasons · frost passes Apr 2, returns Nov 1

Sow Petunia Apr – May, pick May – Oct. Set your climate below and every date on this plate re-times itself.

Sowing window

Apr – May

re-timed to your frost dates

Plant out

after Apr 2

once frost risk has passed

First picking

around Jun 14

≈ 60 days from sowing · 80-150 flowers per plant

Composed for —ColdTemperateMildWarmUse my locationUsed once to set your season · only the zone is kept

Week-by-week Petunia reminders watering, feeding and pruning, timed to your dates

In the app

Frost alerts for your garden a warning before a cold night costs you the crop

In the app

Succession sowing dates so the picking never gaps mid-season

In the app

Prefer email? Get monthly reminders in the Almanac

Keep my dates — free for 7 daysWe nudge you as each window opens · cancel anytime

Purchase transplants or start seeds indoors ten to twelve weeks before the last frost date. Petunia seeds are extremely fine and need light to germinate, so press them onto the surface of moist seed-starting mix without covering. Maintain consistent moisture and a temperature of 70 to 75 degrees Fahrenheit for germination in seven to ten days. Transplant hardened-off seedlings outdoors after all danger of frost has passed.

Plant in full sun in well-drained, fertile soil or high-quality potting mix for containers. Space plants twelve inches apart in beds or use three to five plants per twelve-inch hanging basket. Petunias are heavy feeders, especially in containers, and benefit from liquid fertilizer every seven to fourteen days throughout the growing season.

By midsummer, many petunia varieties become leggy and sparse. Rejuvenate them by cutting stems back by half, which stimulates a vigorous flush of new growth and flowers within two weeks. Deadhead spent blooms regularly on grandiflora types, though many modern spreading varieties are self-cleaning. Water at the base when possible, as wet foliage and heavy rain can damage large-flowered types.

Petunias complement a wide range of container and bedding companions. Pair trailing varieties with upright plants like salvia, angelonia, and ornamental grasses for contrast in mixed containers. In the vegetable garden, petunias attract hummingbirds and beneficial insects while their sticky stems trap small pest insects. Their fragrance is said to repel certain garden pests including aphids, tomato hornworms, and squash bugs when planted nearby.

The Society Table

Marigold belongs beside it. Fennel doesn't.

Old growers' knowledge, checked against Petunia's real companion table below — test any plant you're growing.

Grows well in the company of · 3

MarigoldZinniaGeranium

Keep apart · 1

Fennel

Plant Petunia with good neighboursThe planner flags conflicts before they're in the ground

Petunias thrive in fertile, well-drained soil with a pH of 6.0 to 7.0. In containers, use a premium potting mix with good drainage and moisture retention. Feed container petunias weekly with a water-soluble balanced fertilizer at half strength, or every two weeks at full strength. In-ground petunias benefit from a slow-release granular fertilizer worked into the soil at planting and supplemental liquid feeding monthly. Iron deficiency causes yellowing leaves and is corrected with chelated iron applications.

Ideal Temperature

Hardiness Zone Compatibility

Petunias are primarily garden display flowers rather than cut flowers, as individual blooms are short-lived in arrangements. However, small bouquets can be made by cutting stems in the morning with several buds about to open. Deadhead regularly by pinching off spent blooms and their developing seed pods to redirect energy into new flower production. For seed saving, allow a few flowers to develop seed pods and collect when they turn brown and begin to split open.

Storage & Preservation

Fresh petunia stems last only two to three days in a vase, making them impractical as cut flowers. Their beauty is best enjoyed in the garden or container. Petunia flowers can be pressed between parchment paper for botanical crafts, retaining their color reasonably well. Trailing petunia varieties can be brought indoors before frost, cut back, and grown as houseplants on a sunny windowsill through winter, then returned outdoors the following spring.

Troubleshooting Common Problems

Leggy, sparse growth by midsummer is the most common complaint and is resolved by cutting plants back by half to stimulate fresh growth. Tobacco budworm is particularly damaging because the caterpillars feed inside closed buds where sprays cannot reach them. Grandiflora types with large flowers are easily damaged by heavy rain and wind, making them less suitable for exposed locations. Petunias in containers dry out quickly in hot weather and may need daily watering during heat waves.

Growing Tips

1. Start petunia seeds indoors 10-12 weeks before your last frost date, as they have a long lead time from germination to flowering and benefit greatly from an early indoor start.
2. Surface-sow petunia seeds without covering them, as they require light to germinate. Press seeds gently onto moist seed-starting mix and cover the tray with clear plastic to maintain humidity.
3. Pinch young petunia plants when they reach 15 cm tall by removing the top growth just above a leaf node. This encourages branching and results in fuller, bushier plants with many more flower stems.
4. Water petunias at the base of the plant rather than overhead to keep foliage dry and reduce the risk of botrytis blight, powdery mildew, and other fungal diseases that thrive on wet leaves.
5. Feed petunias weekly with a water-soluble balanced fertilizer during the growing season, as they are heavy feeders that require consistent nutrition to sustain their prolific blooming habit.
6. Deadhead spent petunia flowers regularly by pinching off the faded bloom along with the developing seed pod behind it. This redirects the plant's energy from seed production into producing new flowers.
7. Cut back leggy petunias by one-third to one-half in midsummer when they become sparse and stretched. Apply fertilizer after pruning and new growth with fresh buds will emerge within two weeks.
8. Choose the right petunia class for your purpose: Grandiflora for large statement blooms in sheltered containers, Multiflora for weather-resistant mass plantings, and spreading types for ground cover and hanging baskets.
9. Protect petunias from tobacco budworm caterpillars, their most destructive pest, by inspecting buds regularly for small holes and applying Bacillus thuringiensis (Bt) spray at the first sign of damage.
10. Improve container drainage by using a high-quality potting mix with perlite and ensuring pots have adequate drainage holes. Petunias dislike waterlogged roots and are prone to root rot in poorly drained conditions.