Fertilising guide

How to fertilise Petunia 'Supertunia Royal Velvet' (Petunia × atkinsiana 'Supertunia Royal Velvet')— schedule & NPK

Also called Supertunia Royal Velvet, Velvet Purple Petunia.

More about petunia 'supertunia royal velvet'

About Petunia 'Supertunia Royal Velvet'

Petunia × atkinsiana 'Supertunia Royal Velvet' · also called Supertunia Royal Velvet, Velvet Purple Petunia · flowering

Petunia 'Supertunia Royal Velvet' is a popular Proven Winners vegetative petunia bearing rich, velvety deep-purple trumpet flowers from spring to frost. Mounding and trailing, it self-cleans and needs no deadheading, serving as both filler and spiller in baskets and beds. A heavy feeder, it thrives in full sun and rich, evenly moist, well-drained soil.

Growth habit: Vigorous, mounding and trailing; mounds to roughly 25-30cm and trails freely over the sides of baskets and containers, working as both filler and spiller.

Watch for — Yellowing, hungry foliage: As a heavy feeder it pales and stops blooming if underfed; iron chlorosis (yellowing between veins) is common in cool, wet, or high-pH conditions. Feed regularly and correct iron and pH as needed.

What fertiliser petunia 'supertunia royal velvet' actually wants — and why

Petunia 'Supertunia Royal Velvet' is a heavy-blooming flower with a big appetite — a regular high-potash feed through the season is what drives a long, dense display.

A high-potassium ("high-potash") flowering feed — tomato-style or a dedicated bloom/rose feed. Potassium powers flowering; a high-nitrogen feed gives you a leafy plant with disappointing bloom.

For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for petunia 'supertunia royal velvet': match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.

How often to feed petunia 'supertunia royal velvet', and which months

Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For petunia 'supertunia royal velvet':

The dormant-season rule matters more than the exact interval: skip feeding entirely when petunia 'supertunia royal velvet' is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.

What strength to mix for petunia 'supertunia royal velvet'

Follow the flowering-feed label rate for petunia 'supertunia royal velvet', or half strength if feeding very frequently. These plants genuinely use the nutrients — under-feeding shows up fast as a thin display.

Feeding always goes onto already-damp soil, never dry roots — water petunia 'supertunia royal velvet' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the petunia 'supertunia royal velvet' watering schedule.

Signs you are over-feeding petunia 'supertunia royal velvet'

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for petunia 'supertunia royal velvet':

Lots of lush leaves but few flowers (too much nitrogen).
Scorched leaf edges and salt crust from too-strong or too-frequent feeds.
Soft, sappy growth prone to aphids and mildew.

Signs you are under-feeding petunia 'supertunia royal velvet'

Sparse, small, short-lived flowers and pale foliage.
A tired plant that stops blooming early in the season.
Weak growth and poor repeat-flowering after the first flush.

If the symptoms point at watering, light or roots rather than nutrition, the full petunia 'supertunia royal velvet' care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Container-grown petunia 'supertunia royal velvet' accumulates feed salts fast with frequent feeding — water until it drains each time and flush pots with plain water every few weeks to prevent scorch.

Organic vs synthetic feeds for petunia 'supertunia royal velvet'

Organic options

A liquid comfrey or seaweed feed (naturally potassium-rich) plus compost or well-rotted manure as a mulch. UK: comfrey feed, organic Tomorite, or rose feed; US: Espoma Rose-tone or Neptune's Harvest. Feeds and improves soil.

Synthetic / liquid feeds

A high-potash flowering feed on a regular cadence — UK: Tomorite (Levington), Phostrogen or a specialist rose feed; US: Miracle-Gro Bloom Booster or a rose food. Fast, reliable bloom response.

Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.

Fertilising petunia 'supertunia royal velvet' — frequently asked questions

What fertiliser does petunia 'supertunia royal velvet' need?

A high-potassium ("high-potash") flowering feed — tomato-style or a dedicated bloom/rose feed. Potassium powers flowering; a high-nitrogen feed gives you a leafy plant with disappointing bloom. Petunia 'Supertunia Royal Velvet' is a heavy-blooming flower with a big appetite — a regular high-potash feed through the season is what drives a long, dense display.

How often should I feed petunia 'supertunia royal velvet'?

A heavy feeder. Add controlled-release fertiliser at planting and feed weekly with a balanced or high-potash water-soluble fertiliser. Underfeeding produces pale, hungry foliage and stalls flowering; consistent feeding keeps the velvety bloom coming all season. A heavy feeder. Add controlled-release fertiliser at planting and feed weekly with a balanced or high-potash water-soluble fertiliser. Underfeeding produces pale, hungry foliage and stalls flowering; consistent feeding keeps the velvety bloom coming all season. For a hungry bloomer that means feeding regularly — weekly — right through flowering across the main season (spring through early autumn), tapering as blooming ends.

What strength of feed for petunia 'supertunia royal velvet'?

What does over-feeding petunia 'supertunia royal velvet' look like?

Lots of lush leaves but few flowers (too much nitrogen). Scorched leaf edges and salt crust from too-strong or too-frequent feeds. Soft, sappy growth prone to aphids and mildew. Using a high-nitrogen general feed on petunia 'supertunia royal velvet' is the headline mistake — you grow a big leafy plant with few flowers. The second is simply under-feeding a genuinely hungry bloomer and getting a sparse, short display.

Should I flush the soil of petunia 'supertunia royal velvet'?