What are phytoncides?

Phytoncides are volatile organic compounds that plants, especially trees, release into the air. Think of them as a tree’s natural language of protection and communication. They help trees:

• Defend against insects, bacteria, and fungi

• Communicate stress or health to nearby plants

• Shape the microbial world around them

For us, they’re part of why forest air feels so calming and restorative.

Do all trees emit phytoncides?

Almost all trees emit some volatile compounds, but:

Conifers (pine, fir, cedar, spruce, cypress)

→ Highest and most studied phytoncide emitters

→ Rich in compounds like α-pinene, β-pinene, limonene

→ This is why evergreen forests are often highlighted in forest bathing research

Broadleaf / deciduous trees (oak, maple, beech, birch)

→ Yes, they emit phytoncides too

→ Usually lower concentrations and different compounds

→ Often seasonal (stronger in warm months when leaves are active)

Shrubs, herbs, grasses, mosses

→ Also release volatile compounds

→ They contribute to the overall forest “cocktail,” even if subtly

So it’s less “do they emit them?” and more “how much, which kinds, and when?”

What affects phytoncide release?

Phytoncide levels change constantly depending on:

• Sunlight and temperature

• Humidity and rainfall

• Leaf needles vs broad leaves

• Tree health and age

• Wind and air movement

Warm, still days in dense forests tend to hold them longest... like the forest is breathing with you.

The beautiful takeaway

You don’t need a “perfect” forest.

A mixed forest, a riverside trail, a grove of hardwoods, or a stand of pines... all offer different blends of plant chemistry. Your nervous system doesn’t need optimal data; it just needs time, presence, and breath.