Fertilising guide

How to fertilise Altissimo Rose (Rosa 'Altissimo')— schedule & NPK

Also called Altissimo, Altus, Delmur.

More about altissimo rose

About Altissimo Rose

Rosa 'Altissimo' · also called Altissimo, Altus · flowering

Altissimo is a vigorous large-flowered climber bearing single, blood-red blooms up to 13 cm across, each centred on a boss of golden stamens against glossy dark foliage. Introduced by Delbard in 1966, it repeat-flowers from early summer to autumn and is notably disease-resistant, making it a reliable wall or pillar rose for warm, sunny sites.

Growth habit: Stiff, upright large-flowered climber producing strong main canes that are easily trained onto walls, pillars or trellis; flowers on both old and new wood, repeat-blooming through the season.

Watch for — Poor repeat bloom: Skipping deadheading and the post-flush feed reduces later flowering; remove spent blooms and feed after the first flush to encourage rebloom.

What fertiliser altissimo rose actually wants — and why

Altissimo Rose 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 altissimo rose: 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 altissimo rose, 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 altissimo rose:

Feed in early spring as growth begins and again after the first main flush with a balanced rose fertiliser; mulch with compost or rotted manure annually. Stop feeding by late summer so new growth hardens before frost. For a hungry bloomer that means feeding regularly — sparingly through the growing season — right through flowering across the main season (spring through early autumn), tapering as blooming ends.

The dormant-season rule matters more than the exact interval: skip feeding entirely when altissimo rose 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 altissimo rose

Follow the flowering-feed label rate for altissimo rose, 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 altissimo rose first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the altissimo rose watering schedule.

Signs you are over-feeding altissimo rose

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for altissimo rose:

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 altissimo rose

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 altissimo rose care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Container-grown altissimo rose 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 altissimo rose

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 altissimo rose — frequently asked questions

What fertiliser does altissimo rose 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. Altissimo Rose 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 altissimo rose?

Feed in early spring as growth begins and again after the first main flush with a balanced rose fertiliser; mulch with compost or rotted manure annually. Stop feeding by late summer so new growth hardens before frost. Feed in early spring as growth begins and again after the first main flush with a balanced rose fertiliser; mulch with compost or rotted manure annually. Stop feeding by late summer so new growth hardens before frost. For a hungry bloomer that means feeding regularly — sparingly through the growing season — right through flowering across the main season (spring through early autumn), tapering as blooming ends.

What strength of feed for altissimo rose?