What are Fermented Plant Extracts (FPEs)?

Fermented Plant Extracts are liquid concentrates made by fermenting fresh plant material with a carbohydrate source (such as sugar or molasses). Through fermentation, beneficial microbes break down the plant matter, making nutrients, enzymes, organic acids, and plant compounds more bioavailable to other plants.


Think of FPEs as plant-based probiotics and nutrient tonics for your garden.

Commonly Asked Questions

How are FPEs different from liquid fertilisers?

FPEs are not conventional fertilisers. Instead of delivering high levels of soluble nutrients, they: 

  • Feed and stimulate soil microbes
  • Deliver plant-derived growth compounds
  • Improve nutrient cycling and uptake
  • Support plant immunity and stress tolerance

They work best as part of a living soil or regenerative gardening system, rather than as a standalone nutrient solution.

What plants are used to make Fermented Plant Extracts?

Many plants can be used, depending on the desired outcome. Common examples include:

  • Comfrey – potassium, calcium, and growth support
  • Nettle – nitrogen, iron, and trace minerals
  • Pumpkin - adds fruiting
  • Seaweed – hormones, stress resistance, and trace elements
  • Herbs (mint, basil, rosemary) – aromatic compounds and pest resilience
  • Fast-growing local weeds – minerals adapted to your region

At Kai Kai Farm, we prioritise seasonal, locally relevant plant materials wherever possible.

What are plant tonics?

Plant tonics are gentle liquid inputs designed to support overall plant vitality rather than force rapid growth. They may include:

  • Fermented plant extracts
  • Microbial inoculants (such as EM)
  • Mineral solutions
  • Botanical teas

Tonics are ideal for ongoing plant care, recovery, and prevention, not just problem‑solving.

What are the benefits of using FPEs and tonics?

Regular use can help:

  • Improve root development
  • Increase nutrient efficiency
  • Strengthen plant immunity
  • Support flowering and fruiting
  • Improve soil structure and biology
  • Reduce plant stress from heat, cold, or transplanting

Results are usually subtle but cumulative — healthier plants over time, not overnight fixes.

Are Fermented Plant Extracts safe for food gardens?

Yes. When made and applied correctly, FPEs are safe for:

  • Vegetable gardens
  • Fruit trees
  • Herbs
  • Indoor and outdoor plants

They are commonly used in organic, permaculture, and natural farming systems.

How do I use Fermented Plant Extracts?

FPEs are always diluted before use. Typical application methods include:

  • Soil drench: watered into the root zone
  • Foliar spray: applied to leaves (early morning or late afternoon)
  • Compost activation: added to compost or worm farms

A common dilution rate is 1:500 to 1:1000, but this can vary depending on the extract and plant type.

Can I combine FPEs with EM or other microbial products? 

Yes — FPEs pair beautifully with microbial inputs such as EM‑1, bokashi liquids, or compost teas. The plant compounds feed microbes, and microbes help cycle nutrients back to plants.


Always test new combinations on a small area first and avoid mixing with harsh chemical inputs.

 

How often should I apply plant tonics?

For general plant health:

 

  • Every 2–4 weeks during active growth
  • Alternate different FPEs or use Activated EM-1
  • More frequently for stressed or recovering plants (at lower strength)

Consistency matters more than strength. Gentle, regular applications give the best results.

Do Fermented Plant Extracts smell?

Properly made FPEs have a sweet, tangy, or yeasty smell, not a rotten one. A foul odour usually indicates:

 

  • Too much air exposure
  • Incorrect sugar ratios
  • Contamination

If it smells putrid, it’s best not to use it on plants.

Are FPEs suitable for beginners?

Absolutely. They are forgiving, low-cost, and intuitive to use. You don’t need perfect measurements — just clean tools, fresh plant material, and patience.

They’re an excellent entry point into natural gardening and fermentation-based inputs.

Where can I learn more or get started?

We share ongoing guides, products, and seasonal insights through Kai Kai Farm. If you’re just starting out, we recommend beginning with ready-made inputs and simple ferments before experimenting further.

Helpful products to explore:

 

  • Activated EM-1 (AEM): A versatile microbial inoculant for soil, compost, plant tonics, and fermented extracts
  • EM-1 Microbial Inoculant: The foundation culture used to activate EM and support fermentation
  • Bokashi Bran & Bokashi Systems: Ideal for producing nutrient-rich bokashi liquid and closing the food waste loop
  • Plant Care & Soil Health Kits: Curated tools for low-input, regenerative gardening

Fermented Plant Extracts & Tonics

Beginner Recipe #1: Simple Fermented Plant Extract (FPE)

This is a gentle, beginner-friendly recipe using common garden plants.

You’ll need:

  • Fresh green plant material (comfrey, nettle, weeds, herbs) ideally havested before dawn
  • Raw sugar, brown sugar, or molasses
  • Non-chlorinated water (or let tap water sit for 24 hours)
  • A clean jar or bucket with a loose-fitting lid. Tip: Beer brewing containers with airlocks work really well and are normally available for cheap second hand

Method:

  1. Chop plant material into small pieces
  2. Weigh or loosely measure the plant material
  3. Add sugar at roughly a 1:1 ratio by weight (or enough to coat thoroughly)
  4. Mix well until juices begin to release
  5. Pack loosely into your container
  6. Cover (do not seal airtight)
  7. Ferment in a cool, shaded place for 7–14 days, stirring occasionally

 

When ready:

  • Liquid will be dark and aromatic
  • Strain and store the liquid
  • Compost the solids

 

How to use:

  • Dilute 1:500–1:1000 for soil drench or foliar spray

Beginner Recipe #2: Fermented Plant Extract with Effective Microbes (EM-1)

Adding EM-1 introduces additional beneficial microbes in the form of yeasts and phototrophic bacteria and stabilises the fermentation.

You’ll need:

  • Fresh green plant material (comfrey, nettle, weeds, herbs) ideally havested before dawn
  • EM-1
  • Molasses (ideally Blackstrap & no sulphur)
  • Non-chlorinated water (or let tap water sit for 24 hours)
  • A clean jar or bucket with a loose-fitting lid. Tip: Beer brewing containers with airlocks work really well and are normally available for cheap second hand

 

Method: 

  1. Fill container halfway with chopped plant material
  2. Add water to cover
  3. Optional: Add a weight like a brick or rock to weigh down the plant material
  4. Add 1–2 tablespoons molasses per litre of water
  5. Add 1–2 tablespoons EM-1 per litre of water
  6. Stir gently
  7. Cover loosely
  8. Ferment for 14-28 days in a shaded area

 

Smell check: 

  • Sweet, sour, or yeasty = good
  • Rotten or putrid = discard

 

Beginner Recipe #3: Activated EM-1 (AEM)

Activated EM-1 extends your EM supply and is the base for many tonics.

You’ll need:

 

  • EM-1 Microbial Inoculant
  • Unsulphured molasses
  • Non-chlorinated water
  • Airtight bottle or jerry can

 

Basic Ratio:

 

  • 1 part EM-1
  • 1 part molasses
  • 18 parts water

 

Method:

 

  1. Add molasses to warm (not hot) water and dissolve
  2. Add EM-1
  3. Seal container airtight
  4. Store at room temperature for 7–10 days

When ready:

 

  • pH around 3.5
  • Sweet–sour smell (like yoghurt or cider)
  • Orange brown colour

Shelf life:

 

  • Best benefits if used within 7 days. Use within 30–60 days once activated

Troubleshooting & Practical Guide

Fermentation is a living process. Small variations are normal, but the cues below will help you understand what’s happening and how to respond.

My ferment smells bad — what went wrong?

If it smells rotten, putrid, or like sewage: 

  • Too much air exposure
  • Not enough sugar or molasses
  • Container wasn’t clean
  • Temperature too high

 

What to do: 

  • Discard the liquid (don’t apply to plants)
  • Clean container thoroughly
  • Increase sugar or molasses next time
  • Keep ferment shaded and cooler

There’s white film or foam on top — is that okay?

Yes, usually.

  • White foam or thin film: Often harmless yeast activity
  • White fuzzy mould: Usually okay if smell is pleasant
  • Green, black, or colourful mould: Discard

 

When in doubt, trust your nose.

My FPE stopped bubbling quickly

This is normal. Fermentation activity often peaks in the first few days and then slows as sugars are consumed.

As long as the smell remains pleasant, the extract is usable.

Can I ferment different plants together?

Yes. Mixed plant ferments are common and effective.


General guidelines:

 

  • Avoid woody or tough material
  • Prioritise fast-growing green plants
  • Use young leaves, stems and flowers
  • Chop finely for better extraction

 


You can also ferment single plants separately to learn their individual effects.

How strong should my dilution be?

When unsure, dilute more, not less.

 

  • Healthy plants: 1:500–1:1000
  • Young or stressed plants: 1:1000–1:2000


Gentle, repeated applications outperform strong, infrequent ones.

Can I use FPEs on seedlings?

Yes, with caution.

 

  • Use very weak dilutions
  • Apply to soil, not directly to leaves
  • Observe plant response before repeating

How do I store FPEs and Activated EM?

 

  • Store sealed
  • Keep out of direct sunlight
  • Cool, stable temperatures are best

 


FPEs: several months if kept clean


Activated EM-1: best within 30–60 days


If smell changes negatively, discard.

Common beginner mistakes to avoid

 

  • Sealing containers airtight too early (for non-EM ferments)
  • Using chlorinated water
  • Overapplying undiluted extracts
  • Expecting rapid, fertiliser-like results

 


FPEs work gradually by improving biological systems.

How to observe results

Look for subtle changes over time:

 

  • Improved leaf colour
  • Faster recovery from stress
  • Better root growth
  • Increased resilience to heat or pests

 

Observation is the most valuable tool you have.