3+30+300
The T(h)rees Principle for
Better Cities

Trees and green spaces make cities healthier and more vibrant. The ‘T(h)rees Principle’ is an evidence-based rule of thumb that individuals, governments, businesses, and organisations use to improve urban forests in their communities.

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3, 30, and 300

Guiding principles based on science to help us unite in greening our cities and urban experiences

Three

Everyone should be able to see at least three mature trees from their home, work, and school.

North of Luxembourg

Thirty

We should all live in a neighbourhood with at least 30% tree canopy cover.

Three Hundred

Everyone shall have a high-quality, public green space within 300 metres from their home.

Rethinking Urban Green Space
Academic books & papers
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3+30+300 in the Media
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Threes Principle, Trees Principle

Global Reach

The 3+30+300 principle is being used by governments, cities, organisations, and communities around the world. See examples of where the threes for trees rule is put into action.

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History of 3+30+300

With decades of experience in urban forestry and sustainable city development, Cecil has been committed to greening cities worldwide and promoting the multiple benefits of urban trees.

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3+30+300 in conversation.

3+30+300 is Open Access


There is no trademark nor copyright on the 3+30+300 principle to make it easily accessible. That means everyone can use it freely within the basic guidelines, citing the original source. If you make changes to the principle and its components, we ask you clearly indicate this. Partners across the world can help with implementation, including helping you with assessment and monitoring.

Rethinking
the city & the forest.

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