Best Fertiliser for Rosemary — CompleteGrow Feeding Guide for Lush Growth

Rosemary (Salvia rosmarinus) thrives on steady, light nutrition. The goal isn’t giant, sappy growth —
it’s dense, aromatic foliage with strong roots that resist heat, wind, and dry spells. This guide shows you how to feed for fragrance and structure using a balanced, professional liquid.

What Rosemary Actually Needs

Balanced macros (N-P-K): Even ratios (e.g., 20-20-20) support foliage density (N), root & bud development (P), and stress tolerance/flavour concentration (K).
Micronutrients: Mg, Fe, Mn, Zn keep leaves deep green and prevent interveinal yellowing in pots.
Right dose, right timing: Light, frequent feeds outperform heavy, infrequent ones — especially in containers where nutrients leach quickly.

Soil, pH & Water Quality (Aromatics Matter)

Soil: Free-draining sandy/loam mix; add coarse perlite for pots. Avoid waterlogging at all costs.
pH: Target 6.0–7.5. Outside that range, micronutrient uptake drops and flavour suffers.
Water: Rain/filtered is ideal. If tap water is alkaline/hard, add a pinch of food-grade citric acid occasionally to keep pH in range.

Outcome to optimise for: Tight internodes, firm stems, deep green leaves with strong aroma — achieved by
consistent light feeding + excellent drainage + full sun (6–8 hrs).

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Mixing Rates, Feeding Schedules & Advanced Tuning

Recommended Product

Use a balanced liquid like CompleteGrow All Purpose NPK 20-20-20 with full trace elements. Liquids give you precision (dose + timing) and quick correction when plants look tired.

Standard Mixing (Soil & Containers)

Maintenance: 5 mL (1 tsp) per 2 L water, every 14 days in warm seasons.
Container boost (small pots): 5 mL per 2 L, every 10–14 days (leaching is higher).
After pruning/harvest: 5–7 mL per 2 L once within 7 days to support regrowth (then return to maintenance).

Seasonal Schedule (Warm Climate Baseline)

Spring: Fortnightly feeds; increase sun exposure for compact form.
Summer: Maintain fortnightly; water in mornings; avoid feeding in >32 °C heat.
Autumn: Reduce to monthly as growth slows; prune lightly after final harvest.
Winter: Pause feeding in cold zones; resume at the first flush of new growth.

Foliar Feeding (Rapid Correction)

Dilute to ¼ strength (≈1–2 mL per 2 L) and mist foliage in early morning every 2–3 weeks when leaves look pale.
Avoid midday sun; foliar is for quick fixes, not a replacement for root feeding.

Irrigation & Drainage Rules (Critical for Flavour)

Let the top 2–3 cm of mix dry between waterings; rosemary hates “wet feet.”
Deep, infrequent watering develops resilient roots and better essential oil profiles.
Use coarse mulch (not soggy) to buffer heat and reduce nutrient loss after feeding.

Pruning/HARVEST → Feed Loop

Harvest/prune lightly after a growth flush.
Within a week, apply one feed at maintenance strength.
Resume the normal cadence; aim for compact, branching plants with tight internodes.

Pro Tip: If foliage is very soft and stretched, back off nitrogen (skip one feed), increase light, and allow slightly deeper dry cycles. If colour is fading, resume the regular 20-20-20 cadence and check pH.

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Troubleshooting & FAQs

Common Issues (Fast Diagnostics)

Pale leaves / weak aroma: Irregular feeding or high pH. Resume fortnightly 20-20-20; nudge irrigation pH toward 6.5.
Leggy, soft growth: Too little light or excess nitrogen. Increase sun; skip one feed; tighten watering cycle.
Yellowing from the bottom: Overwatering or poor drainage. Open the mix (perlite), water less often, ensure pot holes are clear.
Tip burn / salt crust: Over-feeding or evaporation salts. Flush with plain water for 2–3 irrigations, then resume lighter dosing.

FAQ — Rosemary Feeding

How often should I fertilise rosemary?
Every 14 days in spring–summer for beds; every 10–14 days (half-strength) in pots. Monthly in autumn; pause in winter for cool climates.

Can I use “herb only” or citrus fertilisers?
Many over-emphasise nitrogen or lack trace elements. A balanced 20-20-20 with micros delivers denser foliage and better colour without sappy growth.

Will fertilising change flavour?
Heavy nitrogen can dilute oils. Use light, regular feeds and full sun to maintain strong aroma.

What about foliar feeding?
Great for quick green-up at ¼ strength, early mornings only. Keep the main program root-fed.

CompleteGrow Recommendation

Feed with CompleteGrow All Purpose Liquid NPK 20-20-20 at 5 mL per 2 L every 14 days (pots: every 10–14 days at half-strength). This balanced, micronutrient-fortified formula keeps rosemary compact, aromatic, and resilient through the growing season.