Organic Fertilizers

Mineral fertilizers are industrially manufactured compounds with precisely defined nutrient content. Nutrients are present in the form of ions immediately available to roots – the effect is rapid and easily measurable using an EC meter.

Organic Fertilizers – a Complete Guide for Gardeners

1. Organic vs. Mineral Fertilizers – Basic Differences

Mineral (Synthetic) Fertilizers

Organic fertilizers come from natural sources – plant, animal, or mineral. Nutrients are released gradually as soil microorganisms decompose organic matter. The speed of this process depends primarily on temperature, moisture, and the activity of the microbial community in the soil.

Comparison Table

Parameter	Organic Fertilizers	Mineral Fertilizers
Source	Natural (compost, guano, bone meal)	Industrial synthesis
Nutrient Availability	Slow, gradual (days–weeks)	Immediate
Risk of Over-fertilization	Very low	High
Effect on Soil Life	Positive – supports microbiome	Neutral to negative
Effect on Soil Structure	Improves (humus, soil aggregates)	None
Dosing Precision	Lower (variable NPK content)	Very high
Suitability for Hydroponics	Limited (risk of system clogging)	Ideal
Smell	Often pronounced	Minimal
Cost per Unit of Nutrient	Higher	Lower
Ecological Impact	Low	Higher (production, water runoff)
Certification for Organic Production	Yes (if conditions met)	Usually no

When to Choose Organic and When Mineral

Organic fertilizers are ideal if:
- You grow in soil or coconut substrate.
- You want to build soil fertility and structure long-term.
- The taste and quality of harvested produce matters to you.
- You prefer a natural approach with lower dosing error risk.

Mineral fertilizers are more suitable if:
- You grow in hydroponics (DWC, NFT, Ebb & Flow).
- You need immediate correction of nutrient deficiency.
- You require precise EC control and specific nutrient ratios.
- You grow commercially and optimize yields with emphasis on reproducibility.

2. Main Nutrients – NPK and What They Mean

Macronutrients (NPK)

Element	Symbol	Function in Plant	Deficiency Symptoms
Nitrogen	N	Vegetative growth, chlorophyll formation, protein synthesis	Yellowing of lower leaves, slow growth
Phosphorus	P	Root system development, flowering, energy metabolism (ATP)	Purple or red leaves, weak roots
Potassium	K	Stress resistance, nutrient transport, water regulation	Brown leaf margins, wilting

Secondary Macronutrients

Element	Function
Calcium (Ca)	Cell wall strengthening, support of root growth
Magnesium (Mg)	Central atom of chlorophyll molecule, key for photosynthesis
Sulfur (S)	Protein and enzyme synthesis, formation of aromatic compounds

Micronutrients

Iron (Fe), manganese (Mn), zinc (Zn), boron (B), copper (Cu), molybdenum (Mo) – plants need them in small quantities, but they are irreplaceable for proper enzymatic processes. Their deficiency is most often manifested by interveinal chlorosis or young leaf deformations.

3. Types of Organic Fertilizers

3.1 Compost

Compost is stabilized decomposed organic matter – kitchen scraps, leaves, grass, wood chips. It is a fundamental building block of healthy, biologically active soil.

Parameter	Value
NPK	approximately 1-1-1 (highly variable depending on feedstock)
Main Benefit	Humus formation, soil structure improvement, microbiome support
Speed of Effect	Slow (weeks–months)
Use	Garden beds, pots, mulching

How to Compost Correctly:

Alternate green and brown layers – green materials (kitchen scraps, fresh grass) provide nitrogen, brown materials (dry leaves, cardboard, sawdust) provide carbon. Optimal C:N ratio is 25–30:1.
Maintain adequate moisture – compost should be moist like a wrung-out sponge. Too dry slows decomposition, excessive moisture creates anaerobic conditions and odor.
Mix regularly – oxygen supply significantly speeds up aerobic decomposition. Mixing once every 1–2 weeks is sufficient.
Monitor temperature – active compost reaches 55–65 °C, which reliably destroys weed seeds and most pathogens.
Finished compost has dark color, crumbly texture, and smells like forest soil. With optimal management, it's ready in 3–6 months.

For home composting, we offer composters of various sizes.

3.2 Worm Castings (Vermicompost)

Worm castings result from organic matter passing through the digestive tract of worms, where it becomes enriched with beneficial microorganisms, enzymes, and chelated micronutrients. The result is the biologically most active organic fertilizer available to ordinary gardeners.

Parameter	Value
NPK	approximately 1-0.5-0.5
Main Benefit	60+ micronutrients, live beneficial bacteria, enzymes
Microbial Activity	10–20× higher than common garden soil
Speed of Effect	Medium (days–weeks)
Use	Substrate amendment (10–30 %), compost tea, top-dressing

Key Advantages of Worm Castings:

Over-fertilization practically impossible – nutrients are bound in organic form and release gradually according to plant needs.
pH buffering effect – stabilizes soil reaction in the optimal range for nutrient uptake.
Disease suppression – dense community of beneficial microorganisms competes with fungal pathogens.
Improved physical soil properties – increases water retention and aeration simultaneously.

3.3 Bat Guano

Bat guano is excrement collected from cave-dwelling bats. It is naturally rich in phosphorus, micronutrients, and amino acids. Composition varies significantly depending on guano age and bat diet – this directly determines which specific type is most suitable for each growing stage.

Guano Type	NPK	Suitable For
Fresh (insectivores)	~10-3-1	Vegetative Stage (high N)
Old (fossil)	~1-10-1	Flowering Stage (high P)
Guanokalong powder	1-10-1	Flowering, root system stimulation

The Guanokalong brand offers certified organic guano in powder and pellet form.

3.4 Bone Meal

Bone meal is made from ground animal bones, sometimes after prior heat treatment. It represents one of the richest organic sources of phosphorus and calcium with relatively long-lasting effect.

Parameter	Value
NPK	approximately 3-15-0
Main Benefit	Phosphorus for roots and flowering, calcium for cell walls
Speed of Effect	Slow (1–4 months)
Use	Mix into substrate before planting or as top-dressing

3.5 Blood Meal

Blood meal is dried and ground animal blood – a concentrated organic source of quickly available nitrogen. Among organic fertilizers, it is one of the fastest-acting.

Parameter	Value
NPK	approximately 12-0-0
Main Benefit	Quickly available organic nitrogen for vegetative growth
Speed of Effect	Relatively fast (days–weeks)
Use	Top-dressing, substrate amendment to speed decomposition
Caution	Excessive use can cause root burn

3.6 Fish Meal and Fish Emulsion

Fish products provide a complete nutrient spectrum – macronutrients and micronutrients – supplemented with naturally present amino acids that plants directly utilize for protein synthesis.

Parameter	Value
NPK	approximately 5-2-2 (meal) / 5-1-1 (emulsion)
Main Benefit	Balanced nutrition, amino acids, stimulation of soil microbiome
Speed of Effect	Medium
Use	Watering (emulsion) or substrate amendment (meal)
Disadvantage	Pronounced odor, especially at higher temperatures

3.7 Seaweed Extracts (Kelp, Seaweed)

Seaweed products are not primary NPK sources – they function as biostimulators. They contain natural growth hormones (auxins, cytokinins), micronutrients, and amino acids that improve plant resistance to abiotic stress (drought, frost, transplanting).

Parameter	Value
NPK	approximately 1-0-4
Main Benefit	Natural phytohormones, stress resistance, germination support
Use	Foliar spray, watering, seed soaking before sowing

4. Compost Tea – Living Nutrition

Compost tea is a water extract from compost or worm castings, enriched with oxygen through aeration. When properly prepared, it contains billions of beneficial bacteria, fungi, and protozoa that, after application, colonize the rhizosphere and protect roots from pathogens.

Preparation of Aerobic Compost Tea

Fill a mesh bag with quality compost or worm castings – ratio 1 part to 5 parts water.
Submerge in a container with dechlorinated water – chlorine in tap water decimates beneficial microorganisms.
Insert an aquarium pump with an air stone. Continuous oxygen supply supports aerobic bacteria and suppresses anaerobic pathogens.
Add a teaspoon of unsulfured molasses as energy source for bacteria.
Let it bubble for 24–36 hours at room temperature (ideally 20–25 °C).
Use the resulting tea immediately for watering or foliar spray – without oxygen, aerobic organisms quickly die.

5. Organic Fertilizers for Indoor Growing – Brand Overview

Indoor growing places specific demands on organic fertilizers: they must be sufficiently soluble, must not clog drip or sprinkler systems, and must provide consistent, controllable nutrition even in a closed environment.

5.1 BioBizz

BioBizz is a renowned Dutch brand with a complete organic system including substrates and fertilizers, optimized to work together.

Product	NPK	Stage	Description
Bio-Grow	4-3-6	Vegetation	Base organic fertilizer based on sugar cane molasses extract
Bio-Bloom	2-7-4	Flowering	Complete flower fertilizer with micronutrients
Top-Max	0.1-0.01-0.1	Flowering	Biostimulant – humic and fulvic acids for larger, more aromatic fruits
Fish-Mix	5-1-4	Vegetation	Fish emulsion for intense vegetative growth and soil microbiome activation
Root-Juice	–	All stages	Root stimulator combining mycorrhizae and humic acids
Acti-Vera	–	All stages	Aloe vera extract increasing stress resistance and supporting plant immunity

The complete BioBizz range is available at Pestík.cz.

5.2 BioTabs

BioTabs is a unique organic fertilization system based on tablets with controlled, long-term nutrient release – especially suitable for growers who prefer a minimalist approach to fertilization.

Product	NPK	Description
BioTabs Tablets	15-7-8	Slow nutrient release over 8–10 weeks
Startrex	–	Humus activator with probiotics to start soil ecosystem
Orgatrex	–	Liquid organic fertilizer usable in all growing stages
Mycotrex	–	Mycorrhizal fungi for maximum root system development
Bactrex	–	Beneficial bacteria (Bacillus subtilis, Trichoderma harzianum)

The BioTabs system principle is simple: insert a tablet into the substrate at planting, activate with Startrex, and then water with clean water, optionally supplementing with Orgatrex. The system is intentionally designed as "just add water" – ideal for less experienced growers or those wanting to minimize fertilization time.

BioTabs products are available in our range.

5.3 Guanokalong

Product	NPK	Description
Guano Powder	1-10-1	Bat guano in powder form for substrate mixing
Guano Pellets	1-10-1	Pelletized guano for convenient and precise dosing
Guano Liquid	–	Liquid extract suitable for watering and foliar application
Guano Complete Mix	–	Pre-mixed substrate with guano for immediate use

6. NPK Ratios and Dosing Schedules

General Plant Requirements in Different Stages

Stage	N Need	P Need	K Need	Ideal Ratio
Seedlings	Low	Medium	Low	1-1-1
Vegetation	High	Medium	Medium	3-1-2
Transition to Flowering	Medium	High	High	1-2-2
Full Flowering	Low	High	High	0.5-3-3
Maturation	Minimal	Medium	High	0-1-2

Example Dosing Schedule – BioBizz in Soil

Week	Bio-Grow (ml/l)	Bio-Bloom (ml/l)	Top-Max (ml/l)	Note
1–2	–	–	–	Nutrients supplied by All-Mix substrate
3–4	2	–	–	Fertilization start, low doses
5–6	4	–	–	Full vegetative stage
7 (transition)	2	2	1	Reduce N, increase P and K
8–10	1	4	4	Full flowering
11–12	–	4	4	Late flowering stage
13	–	–	–	Flush with clean water

Note: This schedule is orientational. Monitor individual plant response and continuously adjust doses. Organic fertilizers are generally forgiving, yet the proven rule applies – start with lower doses and increase as needed.

7. Root Stimulators and Supplements

Organic supplements are not primary NPK sources. Their role is to improve nutrient uptake, support root zone health, and increase overall plant resilience – effects manifested especially in challenging conditions or when growing less hardy varieties.

Supplement Type	Function	Examples
Root Stimulators	Support root growth, facilitate mycorrhizal network formation	BioBizz Root-Juice, Canna Rhizotonic
Humic Acids	Improve cation exchange capacity of soil (CEC), chelate micronutrients	BioBizz Top-Max, BioTabs Startrex
Fulvic Acids	Increase cell membrane permeability and uptake of chelated nutrients	Diamond Nectar (TA)
Enzymes	Decompose dead roots, keep root zone clean	Cannazym, Hygrozyme
Beneficial Microorganisms	Trichoderma, Bacillus – biological root protection against pathogens	BioTabs Bactrex, Mycotrex

The complete range of root stimulators and fertilizer supplements can be found at Pestík.cz.

8. Composting – From Basics to Advanced Techniques

Hot vs. Cold Compost

Parameter	Hot Compost	Cold Compost
Temperature	55–70 °C	Ambient temperature
Maturation Time	3–8 weeks	6–12 months
Maintenance Requirements	Frequent mixing	Minimal
Weed Seed Elimination	Yes	No
Pathogen Elimination	Yes	Only partial
Suitable For	Experienced composters with time	Beginners and passive approach

What to Compost and What Not

Compost YES	Compost NO
Fruit and vegetable scraps	Meat, fish, dairy products
Leaves, grass (dry and fresh)	Diseased plants
Coffee grounds, tea bags	Dead animals
Eggshells	Cooking oil and fats
Cardboard, newspapers (shredded)	Black walnut nuts
Sawdust, small twigs	Animal waste from carnivores
Poultry manure (aged)	Coal and coal ash

Vermicomposting (Worm Composting)

Vermicomposting uses worms – typically Eisenia fetida species (California red worm) – to transform organic waste into biologically highly active worm castings. It is a method accessible even to apartment dwellers.

Advantages over Traditional Composting:

Significantly faster waste processing (2–3 months vs. 6–12).
With proper management, practically odor-free.
Operation possible in apartments using a compact vermicomposter.
Resulting product contains substantially higher microbial activity than traditional compost.

9. EU Regulations for Organic Fertilizers

EU Regulation 2019/1009 (FPR – Fertilising Products Regulation)

As of July 16, 2022, a harmonized EU regulation on fertilizing products applies. Key points:

CE Mark – products meeting FPR requirements can display CE marking and freely trade in all member states without further national approval.
Product Categories (PFC) – regulation defines 7 categories: fertilizers, liming materials, soil conditioners, growing substrates, inhibitors, biostimulants, and mixed products.
Material Categories (CMC) – precisely defines allowed input materials for organic fertilizers (compost, digestate, animal by-products, etc.).
Heavy Metal Limits – maximum concentrations set for cadmium, mercury, nickel, lead, arsenic, and chromium.
Pathogen Limits – Salmonella must not be present in 25 g sample; E. coli max. 1,000 CFU/g.

Czech Legislation – Act No. 156/1998 Coll.

In the Czech Republic, ÚKZÚZ (Central Inspection and Testing Institute for Agriculture) handles registration and supervision of fertilizers. Organic fertilizers must be registered according to Act No. 156/1998 Coll. on Fertilizers.

Key Requirements:

Registration proceedings last maximum 60 days.
Registration is valid for 5 years with renewal option.
Fertilizers from bio-waste are subject to stricter regime – require laboratory analyses and evidence of harmlessness.
ÚKZÚZ conducts regular quality controls of fertilizers on the market.

What This Means for Growers

Buy from verified manufacturers – certified brands (BioBizz, BioTabs, Guanokalong) meet current EU standards.
Check labels – must state NPK content, organic matter percentage, pH, and information on raw material origin.
Beware of unregistered "homemade" mixes – selling non-certified fertilizing preparations violates current legislation.

10. Organic Fertilization for Specific Crops

Tomatoes and Peppers

High calcium requirement – essential for preventing blossom-end rot in fruits.
During flowering stage, increase phosphorus and potassium share (fossil guano, bone meal).
Regular top-dressing with compost every 3–4 weeks maintains microbial activity in root zone.

Herbs

Fertilize moderately – over-fertilized herbs grow vigorously but lose aroma and flavor intensity.
As substrate amendment, compost or worm castings at 10–20% proportion is sufficient.
Occasional watering with diluted seaweed extract supports stress resistance and plant immunity.