Garden flowers

Petunia

PetuniaSolanaceae
AT A GLANCE
Full sun Water: average H2down to 1 °C 20–40 cm tall · 30 cm–1 m trailing for basket types wide In a pot: yes
Flowering · UK
Flowering · Northern Italy
Flowering · Central Italy
Flowering · Southern Italy and islands

This is a genuinely hungry and thirsty bedding plant compared to most others in this KB — regular feeding and, in containers, potentially daily watering through summer are what keep the display going, rather than the more modest routine that suits genera like Cosmos or Tagetes.

Care

Light

Needs as much sun as possible for the strongest flowering; flowers thin out noticeably in shade.

Water

Regular watering, especially in pots and hanging baskets, which dry out fast in summer and can need daily watering in hot weather.

Soil

Fertile, free-draining compost or soil.

Pruning

Deadhead regularly to prolong flowering; many modern self-cleaning varieties need little deadheading, but trimming back leggy trailing stems by a third mid-season refreshes the display.

Feeding

Feed weekly with a high-potash liquid feed for the whole season — a basket petunia flowering non-stop in a few litres of compost runs out of nutrients within weeks and turns yellow and leggy without it.

Propagation

Softwood cuttings from trailing types in late summer, overwintered frost-free on a bright windowsill. Seed-raised petunias are cheap enough that most gardeners simply buy plants each spring, which is a perfectly honest choice.

Month by month

Months change with the climate: in southern Italy tomatoes go out two months earlier than in England.

  1. MayPlant out once the risk of frost has passed. how ›
  2. JuneFeed regularly through summer, especially in pots and baskets — this genus is a hungry, fast-growing bedding plant. how ›
  3. JulyDeadhead and trim back leggy growth to keep the display fresh through to autumn. how ›

Months based on climate: UK. Your choice stays on this device.

  1. AprilPlant out once the risk of frost has passed. how ›
  2. JuneFeed regularly through summer, especially in pots and baskets — this genus is a hungry, fast-growing bedding plant. how ›
  3. JulyDeadhead and trim back leggy growth to keep the display fresh through to autumn. how ›

Months based on climate: Northern Italy. Your choice stays on this device.

  1. AprilPlant out once the risk of frost has passed. how ›
  2. JuneFeed regularly through summer, especially in pots and baskets — this genus is a hungry, fast-growing bedding plant. how ›
  3. JulyDeadhead and trim back leggy growth to keep the display fresh through to autumn. how ›

Months based on climate: Central Italy. Your choice stays on this device.

  1. MarchPlant out once the risk of frost has passed. how ›
  2. JuneFeed regularly through summer, especially in pots and baskets — this genus is a hungry, fast-growing bedding plant. how ›
  3. JulyDeadhead and trim back leggy growth to keep the display fresh through to autumn. how ›

Months based on climate: Southern Italy and islands. Your choice stays on this device.

Common problems

Leggy, bare-based growth by midsummer

How to spot it. Flowers only at the stem tips, bare and woody lower down.

What to do. Trim back by around a third to encourage bushier, fresh regrowth — this genus responds well to a mid-season cutback, especially trailing basket types.

Drying out in pots and baskets

How to spot it. Wilting, especially in hot weather.

What to do. This genus in a container needs frequent, sometimes daily, watering in summer — the fast growth and heavy flowering make it thirstier than most summer bedding.

Grey mould/botrytis on flowersfull sheet ›

How to spot it. Fuzzy grey growth on flowers, especially double-flowered types, after wet weather.

What to do. Deadhead affected blooms promptly and improve air circulation between plants.

Questions

Petunia: is it hardy?

H2: Tender. It survives down to 1 °C.

Can it grow in a pot?

One of the most popular bedding plants for pots and hanging baskets, particularly trailing types.

Petunia: when do you prune it?

Deadhead regularly to prolong flowering; many modern self-cleaning varieties need little deadheading, but trimming back leggy trailing stems by a third mid-season refreshes the display.

Petunia: when does it flower?

In the climate of UK it flowers in June–October.

When do you feed it?

Feed weekly with a high-potash liquid feed for the whole season — a basket petunia flowering non-stop in a few litres of compost runs out of nutrients within weeks and turns yellow and leggy without it. Feeding months, UK: May–September.