Nutrition: timing, dosage, results
For roses, a good fertilising programme is all about timing: a starter feed in spring, top-ups between flushes of flowers, then a potassium-focused feed at the end of summer and a nitrogen stop. Here you’ll find both CRF and liquid protocols, indicative doses (worked in under mulch), warning signs (over-fertilising, deficiency symptoms), and separate sections for pots and public plantings. Do you tend to give a bit too much, or are you more worried you’re not feeding enough?
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Quick principles Principles & materials Timing Dosage – CRF (slow-release) Dosage – liquid Organic supplements Pots / patio Public and green spaces Signs & troubleshooting Tools you’ll need FAQ
Related: Planting • Watering • Soil & pH • Positioning – Private garden • Positioning – Pot/patio • Roses not thriving? Diagnostics
Quick principles
- Basic rule: always fertilise on moist soil, then water in afterwards.
- Season starter: CRF in spring (3–4 months); top-up after the first main flush of bloom.
- Late summer: potassium-focused; after mid-August no nitrogen.
- Ring: spread in a ring with a radius of 30–40 cm around the plant, not right next to the stem.
- Mulch: fertiliser should go under the mulch – this releases nutrients more evenly.
Own-root plants – good ability to regenerate; too much nitrogen leads to lush but weak growth.
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Principles & materials
- CRF (controlled-release): 15-9-12 (+Mg+micro) or 16-8-12 for spring; 10-7-20 / 12-8-16 for summer.
- Liquid: rose feed during the season (every 2–4 weeks) – ideal for quick correction.
- Organic: compost, worm castings, seaweed extract, biochar/zeolite – to improve soil structure and buffering capacity.
Because nutrient uptake depends on pH, test regularly: Soil & pH.
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Timing
- Spring: from bud swell, work a starter CRF into the soil.
- After the first main flush of flowers: top up (CRF or liquid).
- Late summer: potassium-focused feed (helps stems to ripen and harden).
- Autumn: no nitrogen – it encourages soft, frost-sensitive shoots.
The “last nitrogen” deadline is typically between 10 and 15 August, depending on your climate zone.
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Dosage – CRF (slow-release)
| Type | Guideline dose / plant | Note |
| Mini / Patio | 15–25 g | In pots, preferably mixed into the compost |
| Hybrid tea / Floribunda | 30–50 g | Spread in a ring and work in shallowly |
| Shrub / English | 40–70 g | Bigger bush = higher dose |
| Groundcover | 25–40 g | Spread evenly over the surface |
| Climber / Rambler | 50–80 g | Apply near the support, targeting the root zone |
- Method: fertiliser should go under the mulch; work in shallowly to a depth of 5–8 cm, then water in.
- Soil moisture: do not apply to dry soil – water beforehand.
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Dosage – liquid
- Frequency: every 2–4 weeks during the season; use sparingly in heatwaves.
- To the soil: always apply to pre-moistened soil (for better uptake).
- Strength: follow the manufacturer’s label; in containers, use a weaker solution.
Combined with mulch you get more even water and nutrient supply: Mulching.
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Organic supplements
- Compost: a 2–3 cm layer under the mulch; improves structure and soil life.
- Worm castings: rich micro-life; good both when planting and worked into the surface.
- Seaweed extract: boosts stress tolerance (after heat or drought).
- Biochar / zeolite: improves buffering, holds water and nutrients (in small amounts).
pH dependence and dosages: Soil & pH.
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Pots / patio
- CRF in the mix: 2–5 g/L of compost (applied gradually), refresh the top 5–8 cm each year.
- Liquid: weaker solution but more often; do not leave water sitting in the saucer.
- Growing medium: open, airy mix (soil + compost + perlite/pumice); pH changes more quickly → test more often.
Positioning: Pot / patio • Watering: Watering.
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Public and green spaces
- Protocol: work in CRF in spring, top up potassium in summer; use liquid feed only when needed.
- Compost: 2–3 cm under the mulch each year; apply evenly at bed/plot scale.
- Operations: before mechanical application, check soil moisture; water in via the irrigation system.
Positioning: Public and green spaces.
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Signs & troubleshooting
- Chlorosis (yellow leaves with green veins): iron deficiency / high pH → acidify and add iron.
- Thin, spindly shoots, very dark green leaves: too much nitrogen → cut back, increase potassium.
- Scorched leaf edges: over-application / dry compost → thorough watering, temporary pause.
- Poor growth despite good watering: lack of organic matter → add compost.
Always fertilise on moist soil; avoid applying during heatwaves and in blazing midday sun.
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Tools you’ll need
- CRF rose fertiliser
- Liquid rose fertiliser
- Compost
- Worm castings
- Biochar / zeolite
- Watering can / Hose
FAQ
Can I fertilise before rain?
Yes, before moderate rainfall it is beneficial; avoid before storms, as nutrients can be washed away.
Which is better: CRF or liquid feed?
They play different roles: CRF provides the base supply, liquid feed is for quick correction. Used together they give the most even results.
When should I start again in spring?
Around bud swell (according to your local weather), then top up after the first main flush of flowers.
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