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Red Clover (Trifolium pratense) flower and leaves

Making Herbal Infusions & Decoctions: Your Complete Beginner’s Guide

Water extractions (teas) are the simplest, most accessible herbal preparations. Free/low-cost (herbs + water), immediate results, foundational skill.

What This Guide Will Teach You

Water is humanity’s original medicine—heating plants in water to extract their healing properties is perhaps the oldest form of herbalism, practiced for tens of thousands of years across every culture. Whether you call it tea, tisane, infusion, or decoction, the principle is simple: hot water unlocks water-soluble compounds from plants, creating safe, effective medicine.

This guide will teach you two fundamental water extraction methods—infusions for delicate plant parts like leaves and flowers, and decoctions for tough materials like roots and barks. You’ll learn why temperature and time matter, which herbs suit which method, and how to make both quick cups of tea and powerful overnight mineral tonics. By the end, you’ll understand water extraction deeply enough to make informed decisions about every cup of herbal tea you prepare.

Understanding the Two Methods

Infusions: Steeping Delicate Parts

What it is: Pouring hot water over herbs and letting them steep, covered, without continued heating.

Best for: Leaves, flowers, delicate berries, aromatic seeds

Why: These plant parts have thin cell walls and contain compounds (like volatile oils) that would be damaged or lost with prolonged heating.

Think of it as: Making regular tea, but steeping longer for medicine

Decoctions: Simmering Tough Parts

What it is: Simmering herbs in water over heat for 20-45 minutes to break down tough plant material.

Best for: Roots, barks, hard berries, tough seeds, woody mushrooms

Why: These dense materials have lignified (woody) cell walls that require sustained heat to break down and release their compounds.

Think of it as: Making a vegetable stock, extracting everything from tough plant material

The Science Behind Water Extraction

Understanding what’s happening chemically helps you make better herbal preparations.

Why Water Works

Polarity: Water is a polar molecule—it has slightly negative charge on the oxygen end and slightly positive charge on the hydrogen ends. This makes it excellent at dissolving other polar (charged) compounds through electrical attraction.

Hydrogen bonding: Water forms hydrogen bonds with molecules containing oxygen or nitrogen, allowing it to surround and dissolve many plant compounds.

What water extracts well:

Minerals: Potassium, calcium, magnesium, iron (ionic compounds)

Water-soluble vitamins: Vitamin C, B-complex vitamins

Polysaccharides: Including mucilage (soothing compounds), starches, inulin (prebiotic fibre)

Tannins: Astringent polyphenolic compounds

Flavonoids and other phenolics: Many antioxidants

Some alkaloids: Depending on their structure and the pH

What water doesn’t extract well:

Resins: Very lipophilic (fat-loving), require alcohol or oil

Essential oils: Somewhat extract but easily lost to evaporation

Fat-soluble vitamins: A, D, E, K require oil extraction

Waxes and very lipophilic compounds: Need non-polar solvents

The Role of Heat

Heat increases extraction through multiple mechanisms:

Increased molecular motion: Hot water molecules move faster, colliding with plant material more frequently and forcefully

Cell wall disruption: Heat helps break down cellulose and other structural components

Increased solubility: Most compounds become more soluble as temperature rises

Faster diffusion: Compounds move from plant cells into water more quickly

Temperature considerations:

85-95°C (just below boiling): Ideal for delicate flowers and aromatic leaves—preserves volatile oils

100°C (boiling): Good for standard leaf/flower infusions—maximises extraction

Simmering (95-98°C): Perfect for decoctions—sustained heat without violent boiling

What heat can damage:

Volatile oils: Evaporate with steam above 80-90°C

Vitamin C: Degrades with prolonged heating

Some delicate polyphenols: May oxidise with extended high heat

Mucilage: Very prolonged heating can break down these soothing polysaccharides

The Critical Importance of Covering

When you steep an infusion uncovered, you lose medicine with the steam.

What happens: Volatile (easily evaporated) compounds—primarily essential oil components— and escape with steam. These often include the most aromatic and therapeutically valuable compounds.

The solution: Always cover infusions. The volatile compounds condense on the lid and drip back into your tea, preserving the full therapeutic profile.

Visual cue: If you’ve ever noticed droplets on the underside of a pot lid while cooking, that’s condensation. Same principle—those droplets in your tea lid contain medicine.

Why this matters in your daily life:

If you’ve ever wondered why your homemade peppermint tea doesn’t smell as strong as fresh peppermint leaves, or why it doesn’t seem to help your digestion as much as you’d hoped, uncovered steeping is often the culprit. The menthol and other volatile oils that relax your digestive tract literally evaporate into your kitchen air instead of staying in your cup.

Simply covering your mug with a small plate while your tea steeps can double the aromatic compounds that reach your body—meaning noticeably better digestive relief, deeper relaxation, or stronger antimicrobial effects, depending on which herb you’re using. It’s the simplest way to make your herbal medicine significantly more effective, and it costs nothing.

Making Infusions: Step-by-Step

Basic Hot Infusion (Standard Medicinal Tea)

What you need:

The process:

Step 1: Measure herbs

Place herbs in your vessel. For:

Step 2: Add just-boiled water

Pour water that’s just come off the boil over your herbs. For very delicate flowers (lavender, rose), you can let water cool 1-2 minutes first.

Ensure herbs are completely submerged.

Step 3: Cover immediately

Place lid on teapot/jar. If using a mug, cover with a small plate or saucer. This is non-negotiable for aromatic herbs.

Step 4: Steep

Quick sipping tea: 5-10 minutes Standard medicinal tea: 15-20 minutes Strong medicinal infusion: 30 minutes to 1 hour

Longer steeping = stronger flavour and more extracted compounds, but also potentially more bitterness from tannins.

Step 5: Strain and drink

Pour through strainer, pressing herbs gently to extract all liquid. Drink warm, or let cool and refrigerate (use within 48 hours).

Dosing: 1-3 cups daily for most herbs, depending on therapeutic intent.

Overnight Infusion (Nourishing Mineral Extraction)

This method maximises mineral extraction from nutrient-dense herbs.

What you need:

The process:

Step 1: Place herbs in jar Step 2: Fill with boiling water, leaving 2-3cm headspace Step 3: Seal tightly with lid Step 4: Let stand 4-8 hours or overnight at room temperature Step 5: Strain (herbs will have absorbed significant water) Step 6: Drink within 24-48 hours, refrigerated

Best herbs for overnight infusions:

Why this works: Extended contact time in hot (then cooling) water maximises extraction of minerals bound in cell walls. The resulting tea is deeply nourishing and mineral-rich.

Cold Infusion (For Mucilaginous Herbs)

Some herbs benefit from cold extraction to preserve delicate mucilage.

What you need:

The process:

Step 1: Place herbs in jar
Step 2: Cover with cold/room temperature water
Step 3: Seal and let sit 4-8 hours (or overnight) Step 4: Strain and use immediately

Best herbs for cold infusion:

Why cold: Heat can break down long-chain mucilaginous polysaccharides. Cold extraction preserves them intact, giving you maximum soothing, coating properties.

Making Decoctions: Step-by-Step

Basic Decoction (For Roots and Barks)

What you need:

The process:

Step 1: Prepare herbs

Chop or break larger roots/barks into smaller pieces—increases surface area for better extraction.

Step 2: Add to cold water

Place herbs and water in pot. Starting with cold water allows gradual extraction as temperature rises.

Ratio: 1-2 tablespoons herb per cup water, or for larger batches, 30-60g herb per litre.

Step 3: Bring to boil

Heat uncovered until water reaches rolling boil.

Step 4: Reduce to simmer, cover

Reduce heat to maintain gentle simmer (small bubbles, not vigorous boiling). Place lid on pot, leaving slight gap for steam to escape.

Why not fully covered: Prevents boil-over while minimising evaporation.

Step 5: Simmer

Standard roots: 20-30 minutes Very dense/hard materials (chaga, some barks): 45-60 minutes Delicate roots (fresh ginger): 15-20 minutes

Step 6: Strain

Remove from heat, let cool slightly, strain through fine-mesh strainer. Press herbs to extract all liquid.

Step 7: Use or store

Drink warm, or refrigerate and use within 2-3 days.

Dosing: 1-3 cups daily, depending on herb and condition.

Combined Infusion-Decoction (For Mixed Herb Formulas)

When your formula contains both roots and leaves/flowers:

Method:

  1. Make decoction with roots/barks as described above
  2. After simmering, remove from heat
  3. Add leaves/flowers directly to hot decoction
  4. Cover and steep 15-20 minutes
  5. Strain all herbs together

This method gives you proper extraction from both tough and delicate parts without over-cooking leaves/flowers.

Your First Projects

Project 1: Peppermint Digestive Tea (Simple Infusion)

Peppermint (Mentha × piperita) leaves
Peppermint (Mentha × piperita)

Why peppermint?

Peppermint (Mentha × piperita) contains menthol and other volatile oils that:

What you need:

How to make:

  1. Place peppermint in mug
  2. Pour boiling water over
  3. Cover immediately (essential—menthol evaporates easily!)
  4. Steep 10 minutes
  5. Strain and sip slowly

When to use: After meals for digestive comfort, or anytime for refreshment.

Cost (NZ):

Project 2: Ginger-Turmeric Immune Decoction

Why these roots?

Ginger (Zingiber officinale):

Ginger (Zingiber officinale) root
Ginger (Zingiber officinale)

Turmeric (Curcuma longa):

Turmeric (Curcuma longa) one has been cut open to show inside
Turmeric (Curcuma longa)

What you need:

How to make:

  1. Place ginger and turmeric in pot with cold water
  2. Bring to boil
  3. Reduce to simmer, cover partially
  4. Simmer 20 minutes
  5. Remove from heat, strain
  6. Add pinch of black pepper, honey and lemon to taste

When to use: Daily during cold/flu season, or at first sign of illness.

Cost (NZ):

Project 3: Nettle Overnight Mineral Infusion

close up of nettle (Urtica diotica) leaves
Nettle (Urtica diotica)

Why nettle?

Covered in the vinegar guide—extremely mineral-rich. Water extracts these minerals well with extended steeping.

What you need:

How to make:

  1. Place nettle in jar
  2. Fill with boiling water
  3. Seal tightly
  4. Let stand overnight (8 hours)
  5. Strain in morning
  6. Refrigerate, drink throughout day

Taste: Rich, slightly salty-mineral, earthy. Many people find it surprisingly pleasant, especially chilled.

Usage: 1-3 cups daily for mineral support, energy, nutritive tonic.

Cost (NZ):

Where to Source Your Materials in New Zealand

Dried Herbs

Online NZ Suppliers:

Physical Stores:

Typical NZ Pricing:

Growing Your Own (Most Economical):

Many herbs are easy to grow in NZ conditions:

For Seeds and Plants:

Wild Foraging in NZ:

With proper identification, permission, and sustainable practices:

Important NZ foraging considerations:

Fresh Herbs

Equipment

Essential (Start Here):

Nice to Have:

For Decoctions Only:

Optional Upgrades:

Specific Herbs and Their Best Method

Infusion Herbs (Leaves and Flowers)

Peppermint (Mentha × piperita):

Peppermint (Mentha × piperita) leaves
Peppermint (Mentha × piperita)

Chamomile (Matricaria chamomilla):

chamomile flowers in full bloom
Chamomile (Matricaria recutita)

Lemon balm (Melissa officinalis):

Lemon Balm (Melissa officinalis) leaves
Lemon Balm (Melissa officinalis)

Nettle (Urtica dioica):

close up of nettle (Urtica diotica) leaves
Nettle (Urtica diotica)

Calendula (Calendula officinalis):

Calendula (Calendula officinalis) flower
Calendula (Calendula officinalis)

Red clover (Trifolium pratense):

Red Clover (Trifolium pratense) flower and leaves
Red Clover (Trifolium pratense)

Decoction Herbs (Roots, Barks, Hard Materials)

Ginger (Zingiber officinale):

Ginger (Zingiber officinale) root
Ginger (Zingiber officinale)

Dandelion root (Taraxacum officinale):

Botanical drawing of Taraxacum officinale
Dandelion (Taraxacum officinale)

Burdock root (Arctium lappa):

Burdock (Arctium lappa) leaves and flowering heads
Burdock (Arctium lappa)

Cinnamon (Cinnamomum spp.):

Cinnamon (Cinnamomum spp.) dried bark and powdered dried bark
Cinnamon (Cinnamomum spp.)

Astragalus (Astragalus membranaceus):

astragalus (Astragalus membranaceus) slices
Astragalus (Astragalus membranaceus)

Reishi mushroom (Ganoderma lucidum):

Reishi Mushroom (Ganoderma lucidum) fruiting body
Reishi Mushroom (Ganoderma lucidum)

Troubleshooting Common Issues

Problem: Tea is weak, barely tastes like herbs

Cause: Not enough herb, not enough time, or water not hot enough

Solution: Use more herb (don’t be shy—medicinal teas use more than flavoured tea), steep longer (15-30 minutes for infusions), ensure water is actually boiling.

Problem: Tea is extremely bitter, hard to drink

Cause: Too many tannins (over-extracted), or naturally bitter herbs

Solution: Reduce steeping time slightly, or add sweetener (honey, stevia). Some herbs (dandelion root, gentian) are meant to be bitter—their bitterness is therapeutic.

Problem: Tea smells amazing while brewing but loses scent after steeping

Cause: Not covering—volatile oils escaped with steam

Solution: Always cover when steeping aromatic herbs. Those oils contain medicine.

Problem: Tea develops mold or off smell

Cause: Left at room temperature too long

Solution: Infusions last 12-24 hours at room temp, 48-72 hours refrigerated. Make fresh batches or store in fridge.

Problem: Roots/barks aren’t softening even after long simmering

Cause: They’re very dense, or pieces too large

Solution: Chop smaller before decocting, or simmer longer (up to 60 minutes for very hard materials like chaga mushroom).

Safety Considerations

Proper identification: Only use herbs you’ve identified with 100% certainty or purchased from reputable sources. Misidentification can be dangerous.

Allergies: Start with small amounts of new herbs. Discontinue if rash, itching, or digestive upset occurs.

Medication interactions: Many herbs interact with medications:

Pregnancy and nursing: Many herbs are contraindicated. Consult midwife or herbalist before using medicinal amounts.

Children: Most mild herbs (chamomile, peppermint, lemon balm) are safe in appropriate doses. Avoid bitter, stimulating, or very aromatic herbs for young children.

Shelf life:

When to seek medical care:

Herbal teas can support general health and minor, self-limiting conditions, but they are not substitutes for medical care. Seek immediate medical attention if you experience:

  • Severe or worsening pain (chest, abdominal, head)
  • Blood in stool or vomit
  • Difficulty breathing or severe shortness of breath
  • Signs of allergic reaction: severe rash, swelling of face/throat, difficulty swallowing
  • Symptoms lasting more than 2 weeks without improvement
  • Unexplained weight loss or persistent fatigue
  • High fever (above 39°C) or fever lasting more than 3 days

Consult your healthcare provider before using medicinal herbs if you:

Work with your healthcare provider: If you have an ongoing health condition, view herbs as complementary support, not replacement for medical care. Inform your doctor about all herbs you’re using.

Building Your Tea Practice

Start simple. Make single-herb teas. Notice how they taste, how they make you feel, how your body responds. Peppermint for digestion. Chamomile for relaxation. Nettle for energy and minerals.

Then combine herbs. Create blends for specific purposes. Experiment with ratios. Adjust steeping times. Discover what works for your body.

As you gain experience, you’ll develop intuition about methods and timing. You’ll know when to infuse versus decoct, how long to steep for your desired strength, which herbs combine beautifully.

Water-based herbal preparations are the most accessible form of herbalism—safe, affordable, effective, and ancient. Every cup connects you to thousands of years of healing tradition while providing genuine therapeutic support for modern life.

Sources & Further Reading

Books:

Scientific Literature:

New Zealand Resources:

Disclaimer: Does not represent rongoā Māori methods. For rongoā knowledge, consult Te Paepae Motuhake.

Medical Disclaimer: This guide is for educational purposes only and is not medical advice. Herbal teas are appropriate for supporting general health and minor, self-limiting conditions. If you are pregnant, nursing, taking medications, or have chronic health conditions, seek guidance from a qualified health practitioner before using herbs medicinally. Properly identify all plants. The information about plant constituents and traditional uses is educational in nature.

Note on Pricing: All prices mentioned in this guide are approximate and based on New Zealand suppliers as of December 2025. Prices vary by supplier, season, and market conditions. We recommend checking current prices with your local suppliers.

The Public Herbarium is built on a foundation of scientific integrity, transparency, and care. Research sources are referenced throughout the site wherever possible. Content creation is assisted by AI tools and carefully reviewed for accuracy.