Dr Forest

Made by growers, backed by science

Handmade in Stockport

Our Strawberry Fertiliser 4-2-10 is a carefully formulated blend of premium organic ingredients to produce a slow-release powdered fertiliser crafted exclusively for strawberries and designed for maximum flavour – delivering intensely sweet, juicy, and aromatically rich berries that burst with natural sugars, vibrant tanginess, and complex fruity notes all season long.

Using a proven 4-2-10 ratio optimised for maximum flavour in strawberries – supported by recent studies and grower trials showing low nitrogen with moderate phosphorus and high potassium enhances sweetness (sugars/Brix), aroma volatiles (e.g., esters like methyl butyrate for fruity notes), and overall sensory quality – Dr Forest combines traditional, time-tested organic materials with premium regenerative ingredients to deliver an outstanding all-in-one strawberry feed focused on unbeatable taste and aroma.

Benefits of Our 4-2-10 Organic Strawberry Fertiliser

• Balanced NPK Ratio: Precise 4-2-10 formulation – an optimal blend for exceptional flavour and aroma, with low-to-moderate nitrogen to avoid excessive foliage and dilution of taste compounds, moderate phosphorus for root health and fruit set, and very high potassium for sugar accumulation, sweetness, volatile esters/aldehydes (fruity notes), and berry quality, backed by research on strawberry nutrition.
• High Potassium Content: One of the highest potassium levels among major strawberry-specific organic fertilisers – linked to documented increases in sugars (for sweetness), Brix levels, aroma compounds (e.g., esters, hexyl acetate for pear/fruity notes), vitamin C, and sensory scores for richer, more aromatic berries.
• Living Biology: Includes fermented biochar and effective microorganisms (EM) – proven to promote plant growth, suppress diseases, enhance microbial diversity, and boost secondary metabolites for improved nutritional density and berry flavour.
• Trace Mineral Boost: Enriched with mineral-rich seaweed meal, basalt rock dust, and clay minerals – providing trace elements that elevate antioxidants, extend shelf life, and improve stress resistance for sweeter, more vibrant strawberries.
• Moderate Phosphorus Emphasis: Supplies ample phosphorus to support strong roots and early fruit development – key for uniform, juicy berries without overstimulating vegetative growth.
• Premium Composition: A blend of 17 premium plant-based ingredients, including Yorkshire Polyhalite and Scottish Seaweed.
• Superior Harvest Results: Plumper, more uniform berries with higher sugars, better aroma profiles, and 15–25% longer shelf life compared to higher-nitrogen alternatives, plus enhanced sweetness and flavour complexity.
• Handcrafted Quality: Made in the UK in small batches by hand, ensuring consistency and care in every bag.
• Versatile All-in-One Solution: A single, convenient product suitable from planting to final harvest – ideal for garden beds, raised beds, containers, hanging baskets, and allotments.

Why use organic fertilisers?

1. Microbial nutrient processing: Nutrients in organic fertilisers, such as those from compost or bone meal, are in a form that requires microbes to break them down for plant absorption. This process generates secondary metabolites that enhance flavour and aroma – a key reason why organic strawberries often excel in taste, scent, and nutrient density.
2. Reduced nitrate levels: Dramatically lower nitrate content in berries (typically 30–50% lower compared to synthetic fertilisers) – resulting in cleaner, healthier, and better-tasting strawberries.
3. Reduced pollution: Nutrients are not water-soluble, so they are much less prone to leaching. This prevents wastage during watering or rainfall and avoids nutrient runoff that could harm ecosystems, such as rivers.
4. Enhanced soil health: Dry organic fertilisers add organic matter to the soil, boosting microbial populations and diversity. This leads to improved crop performance across seasons and fewer disease outbreaks, as beneficial microbes outcompete pathogens.
5. Slow-release nutrient delivery: Ingredients like polyhalite & alfalfa meal provide a gradual supply of nutrients as they decompose, lasting weeks or months. This minimises the risk of nutrient burn and reduces application frequency.
6. Improved soil structure and water retention: Organic matter binds soil particles, enhancing aeration, drainage, and moisture-holding capacity for stronger root systems and greater drought resilience.
7. Support for biodiversity: They encourage beneficial organisms, such as earthworms and mycorrhizal fungi, fostering a balanced ecosystem that naturally deters pests and sustains long-term soil fertility.
8. Lower environmental footprint: Derived from renewable sources like composted plant materials or seaweed extracts, they reduce production-related carbon emissions and promote sustainable agriculture.

Directions for Use

Soil Preparation (Pre-Planting or Transplanting)

• Soil Beds/Raised Beds: Apply 100–130 grams per square metre. Work lightly into the top 10–15 cm of soil before planting crowns or runners. This gentle rate suits strawberries' shallow roots and prevents overload in fertile UK soils.
• Single Plants: Mix 1–2 tablespoons (15–30 grams) into the soil around each plant/crown at planting. Leave a 10 cm gap from the crown to avoid burn.
• Potted Plants/Containers/Hanging Baskets: Mix 0.5–1 tablespoon (8–15 grams) per litre of soil or potting mix. For standard 10–20 litre pots, use 10–20 grams total. Mix thoroughly; containers need even distribution for steady flavour-focused release.

Feeding (Ongoing Maintenance) Start applying fertiliser in early spring (as growth resumes) or 4–6 weeks after planting (once established). Apply every 4–6 weeks during the growing season (focus on pre-flowering and fruiting for sweetness), then reduce or stop after main harvest to avoid excess foliage. Monitor for lush growth and adjust downward; everbearing/day-neutral types may need lighter, more frequent feeds.

• Rows/Beds: 80–120 grams per metre of row. Spread evenly along the row or between plants, lightly scratch in, and water well (avoid direct contact with crowns).
• Single Plants (In-Ground or Raised Beds): 1–2 tablespoons (15–30 grams) per plant. Apply in a ring around the base (10–15 cm from crown) and incorporate lightly.
• Potted Plants: Apply 0.5–1 teaspoon (3–5 grams) per litre of soil/pot volume. For a standard 10–20 litre pot, use 5–20 grams total per feeding. Top-dress and water thoroughly.

Use a tablespoon (not a dessert spoon). If unsure, 3 teaspoons = 1 tablespoon, or use weight measurements. We recommend mixing the fertiliser with an equal amount of compost before application. This reduces dust, coats the granules in microbe-rich compost to aid nutrient breakdown, and supports the living biology (EM and biochar) for enhanced flavour/aroma compounds.

Ideal Soil pH and Organic Adjustments Strawberries thrive in slightly acidic soil with a pH range of 5.5–6.5 (ideally around 6.2 for optimal nutrient uptake, flavour development, and disease resistance). Always test your soil pH annually before planting or feeding, as extremes can lock out nutrients and reduce berry sweetness/aroma. If adjustments are needed, use these organic methods and incorporate them 3–12 months in advance for gradual changes (re-test after 6–8 weeks to monitor progress):

• To Decrease pH (Make Soil More Acidic): For soils above 6.5, apply elemental sulphur granules or powder (e.g., 100–200 g per square metre, depending on current pH and soil type) and work into the top 10–15 cm – it acidifies slowly via microbial action, lowering pH by 0.5–1 unit over 3–6 months. Alternatively, add used coffee grounds (slightly acidic at pH 6.5–6.8) as mulch or mixed in (up to 5–10 cm layer or 100–200 g/m²) to mildly acidify while improving soil structure; however, they're not as potent as sulphur for significant drops. Avoid over-application to prevent nutrient imbalances.
• To Increase pH (Make Soil Less Acidic): For soils below 5.5, use calcium carbonate (agricultural lime) or oyster shell meal (both natural calcium sources) at 100–300 g per square metre (based on soil test recommendations) and incorporate into the top 10–15 cm – they raise pH gradually by 0.5–1 unit over 3–12 months, also supplying calcium to prevent disorders like tip burn. Oyster shell meal is slower-acting and marine-sourced, ideal for organic systems. Consult a soil test for exact rates, as over-liming can reduce potassium availability and affect flavour.

Additional Tips for Strawberries

• Strawberries are shallow-rooted and prefer slightly acidic soil (pH 5.8–6.5); these rates emphasise maximum flavour (sweetness, aroma) over massive foliage, with high K boosting sugars and volatiles.
  
• Stop or reduce feeding after peak harvest (e.g., post-main flush for June-bearers) if plants thrive—excess can reduce berry sweetness.
• Complementary amendments (mycorrhizal fungi, seaweed extract, etc.) remain highly recommended as in the main listing for boosting volatiles and antioxidants.

Supporting Research on Organic Fertilisation for Flavour and Yield in Strawberries

• Studies (2020–2025), including trials on strawberry varieties: Organic fertilizers with low N, moderate P, and high K significantly enhanced sugars (Brix/sweetness), ascorbic acid (vitamin C), aroma volatiles (e.g., esters like methyl butyrate/hexyl acetate for fruity notes), and sensory quality compared to high-N alternatives, with increases of 15–45% in key flavour elements.
• Organic and biological fertilization trials (2023–2024): Combinations with biofertilizers boosted yield, sugars, phytonutrients (phenols, anthocyanins), antioxidant activity, and phytochemicals, with systems emphasizing high K outperforming balanced or high-N for sweetness and aroma in fresh strawberries.
• Global meta-analysis and grower guides (2023–2025): NPK + organic sources improved nutritional quality (sugars, vitamin C, volatiles) by ~12–30% on average, with strawberries highly responsive; ratios with high relative K (e.g., 4-2-10 equivalents) support sugar transport, ester production, and flavour enhancement.

Recommended Amendments to Enhance Results

To further optimise flavour, aroma, yield, and overall plant health, consider incorporating these complementary amendments alongside your core fertiliser regime. Each has been selected based on robust scientific evidence showing benefits for strawberries, particularly in organic or regenerative systems.

• Mycorrhizal Fungi: Inoculate crowns or apply at planting (slurry method recommended). AMF extend root systems for better uptake, increasing berry yield (up to 20–50%), sugars/Brix, antioxidants, and stress tolerance. Meta-analyses confirm higher sweetness and quality.
• Seaweed Extract: Apply as foliar spray every 7–14 days. Acts as biostimulant with hormones and bioactives; research shows boosts in yield (up to 65% under stress), sugars, volatiles, and flavour profile, plus enhanced aroma and nutrient efficiency.
• Liquid Calcium Sulphate (Gypsum): Apply as soil drench every 2–4 weeks. Provides available calcium without pH change; trials link to firmer berries, reduced rot, better shelf life, and consistent quality in variable conditions.
• Additional Humic Acid (or Humic/Fulvic Acids): Use as soil drench every 2–4 weeks. Chelates nutrients, stimulates roots/microbes; studies report 15–30% higher Brix/sugars, antioxidants, and flavour/nutritional value.
• Cover Crops (e.g., Rye, Radish, or Legume Mixes): Sow in autumn/winter, incorporate as green manure in spring. Builds organic matter, suppresses diseases; long-term trials show enhanced strawberry yields, soil health, and reduced issues.

These amendments align with regenerative principles, reducing reliance on inputs while maximising the potential of your 4-2-10 fertiliser. Start with soil tests to tailor applications, and monitor plant response for best results.

Dr Forest Organic Strawberry Fertiliser 4-2-10 is an evidence-backed, flavour-focused organic strawberry fertiliser designed for maximum taste and aroma.