Getting it to bloom

Why won't my Petunia bloom? (and how to make it flower)

Also called grandiflora petunia, multiflora petunia, trailing petunia (Petunia × hybrida).

About Petunia

Petunia × hybrida · also called grandiflora petunia, multiflora petunia · flowering

Petunias are tender annuals from South America with trumpet-shaped flowers in nearly every colour, grown widely in baskets and containers. They flower from late spring to first frost with deadheading and regular feeding. Pet-safe by ASPCA standards.

Garden petunias are complex hybrids descended from wild South American species (chiefly Petunia axillaris and P. integrifolia); the genus name derives from petun, a Brazilian word for tobacco, the genus's close Solanaceae relative.

Plant type: flowering

Watch for — Leggy plant with few flowers: Stop flowering through midsummer; pinch back hard and feed.

Sources: missouribotanicalgarden.org, extension.umn.edu, web.extension.illinois.edu

The reasons petunia isn't blooming

Almost every non-blooming petunia traces back to one of these, roughly in order of how common they are:

Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.
Too much nitrogen feed, driving lush foliage at the expense of flowers (very common with general or lawn feeds).
The plant has not been deadheaded, so it stops flowering once it sets seed.
Irregular watering — drought or waterlogging at the budding stage makes buds abort.
It is still too young or was checked by a transplant and is rebuilding before flowering.

Feeding petunia a high-nitrogen general feed and growing it in too little sun — you get a big leafy plant and almost no flowers.

The fix — how to get petunia to flower

Maximise sun. Give petunia the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers.
Switch the feed. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.
Deadhead regularly. Remove spent flowers often to keep it producing more rather than stopping to set seed.
Water consistently. Keep moisture even through budding and flowering — drought-then-flood swings make buds drop.

Light and feeding do most of the heavy lifting here. Dial in the spot with the light guide for petunia and get the feeding right with the petunia fertilising schedule — the wrong feed (too much nitrogen) is one of the most common silent reasons a healthy plant makes leaves instead of flowers.

Bloom season and what to expect

Petunia flowers across its growing season (mostly summer) and, kept fed and deadheaded, can bloom for many weeks or right up to frost.

Post-bloom care so it flowers again

Deadhead, keep feeding lightly, and many will rebloom; collect seed from the best plants at the end of the season if you want to grow them again.

For everything else this plant needs day to day, see the full petunia care brief and its watering schedule — a stressed, badly watered plant rarely has the energy to flower at all.

Petunia blooming — frequently asked questions

Why won't my petunia flower?

Petunia blooms on the season's growth given enough sun, warmth and the right feed — there is no cold or photoperiod trick, just good growing conditions and a bloom-leaning feed. The most common reason it is not happening: Too little sun — most of these need full sun (or very bright light) to flower well; shade gives leaves, not blooms.

How do I make petunia bloom?

Give petunia the sunniest spot you have — for most bedding and fruiting plants, more direct light directly means more flowers. Move off high-nitrogen feeds and use a higher-potassium "bloom" or tomato-type feed as it comes into flower.

When does petunia normally bloom?