How to grow Petunia

Petunia × atkinsiana · Petunia hybrida, garden petunia, surfinia

Summer bedding and balcony flower grown from seed as an annual; it blooms from spring until the first frost.

Quick facts

Type	Flower
Family	Solanaceae
Light	Full sun
Soil pH	6–7
Frost	does not tolerate frost
Soil for sowing	from 18 °C
Germination	8 days
Seedlings ready	55 days
Where it grows	Greenhouse, Open ground, At home

When to plant

Sow for seedlings about 9 weeks before planting out.

Plant out in open ground about a week after your last spring frost, once the soil is warm.

In an unheated greenhouse everything moves about three weeks earlier.

Frost dates · When to plant

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	16…24 °C	—
Growth	every 7 days	—	balanced (NPK), at the start of the stage
Flowering	every 7 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 30 days into the stage; balanced (NPK), 60 days into the stage; balanced (NPK), 90 days into the stage

Open ground

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	16…24 °C	—
Growth	every 7 days	—	balanced (NPK), at the start of the stage
Flowering	every 7 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 30 days into the stage; balanced (NPK), 60 days into the stage; balanced (NPK), 90 days into the stage

At home

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	16…24 °C	—
Growth	every 2 days	—	balanced (NPK), at the start of the stage
Flowering	every 2 days	—	balanced (NPK), at the start of the stage; balanced (NPK), 30 days into the stage; balanced (NPK), 60 days into the stage; balanced (NPK), 90 days into the stage

Growing notes

Light

Needs full sun; in shade it grows spindly and gives few flowers.

Soil

Light, well-drained soil of medium fertility, pH 6.0–7.0. Where the ground drains poorly, grow it in a raised bed.

Care

Sow 8–10 weeks before planting out, on the surface of the mix without covering the seed — it needs light — at 22–25 °C. Harden the seedlings off and plant out once the danger of frost is past, 30–45 cm apart; pinching out the tips at planting makes bushier plants. Once established give 25–50 mm of water every 7–10 days rather than frequent light watering, and feed monthly with a balanced fertiliser. Cut leggy plants back by half and feed them. Large-flowered and double petunias need deadheading; many small-flowered ones drop their old flowers by themselves. Water the soil, not the leaves and flowers.

Pests and diseases of Petunia

Sources

Figures checked against these sources.