Best Fertiliser for Climbing Roses

Climbing roses bring height and elegance to garden fences, arches, and pergolas — but unlike smaller bush varieties, they channel enormous energy into long canes before flowering begins. This makes targeted feeding essential to maintain structure, leaf colour, and repeat blooms throughout the year.

Healthy climbing roses rely on deep, steady nutrition. As canes lengthen, they drain nutrients from the soil quickly, especially in poor or shallow beds. A balanced NPK program strengthens stems and supports abundant flower clusters across tall frameworks. The best results come from using
CompleteGrow All Purpose NPK 20-20-20
for structural growth early in the season and
Advanced NPK 4-18-38 + Calcium & Magnesium
to power the flowering phase once buds begin to form.

What Makes Climbing Roses Different

Unlike compact rose bushes, climbers put more energy into vertical cane growth before flowering. This means they demand extra phosphorus for root anchoring and potassium for bloom support along those tall stems. Without enough nutrition, upper canes can yellow or flower sparsely.

A well-fed climbing rose will push strong new shoots from the base, maintain deep green foliage up the full height of the trellis, and set clusters of flowers along every stem — not just the tips.

Key Nutrients for Vertical Strength

Nitrogen builds the leafy framework needed to support heavy blooms.
Phosphorus anchors roots and fuels cane extension from spring through early summer.
Potassium boosts flower count and colour along high stems.
Calcium & Magnesium prevent mid-season leaf yellowing and improve stress tolerance in exposed positions.

A balanced feeding cycle using these nutrients keeps climbers vigorous, full of buds, and beautifully covered from base to tip.

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Feeding Schedule for Climbing Roses

Because of their height and exposure, climbing roses need both structural feeding and flower feeding at different stages. A two-step approach keeps them productive and resilient.

Early Spring: Feed with 20-20-20 to stimulate new cane growth from the base. Apply every three weeks for two months. This helps the plant establish a dense framework before flower buds appear.

Late Spring to Summer: Switch to 4-18-38 + CaMg. The high phosphorus and potassium encourage bud formation along all canes, not just the tops. Feed every 3–4 weeks and water thoroughly after application.

Autumn: Apply a light dose of 4-18-38 once monthly to help strengthen roots and prepare for pruning. This prevents nutrient loss before winter dormancy.

Winter: Pause fertilising during dormancy. Resume light feeding in early spring after pruning.

Always water before feeding, and mulch heavily around the base to conserve moisture. Climbing roses often grow near walls or fences where soil dries quickly — mulch keeps root zones stable and nutrient uptake efficient.

For container-trained climbers, use half-strength doses but maintain the same rotation. Regular flushing prevents salt build-up in restricted soil volume.

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Climbing Rose Feeding Questions

Why do upper canes on my climbing rose look weak?
This often happens when nutrients don’t reach the top growth. High-potassium feeds like 4-18-38 strengthen upper stems and improve bloom density along tall canes.

Can I use a liquid fertiliser on trellised roses?
Yes. Diluted liquid feed ensures nutrients soak into the root zone evenly, especially in raised or narrow beds near fences.

How do I feed after pruning?
After major pruning, apply a light 20-20-20 feed to promote new cane growth from dormant buds. This replenishes energy used for regrowth.

Why are flowers small or only on top of the plant?
Usually from low potassium or irregular feeding. Switch to 4-18-38 and train canes horizontally to encourage even flowering along the length of each stem.

Final Recommendation

Climbing roses flourish when structure and bloom phases are supported equally. Feed early with
CompleteGrow All Purpose NPK 20-20-20
to strengthen canes, then follow with
Advanced NPK 4-18-38 + Calcium & Magnesium
to boost flower size, colour, and endurance. With consistent feeding and proper training, climbers will blanket their supports in full, vibrant blooms year after year.