The evidence ladder
- Horticultural institutions (for example the Royal Horticultural Society).
- University extension services.
- Government agricultural resources.
- Botanic gardens.
- Peer-reviewed research, where it answers a practical question.
- Established specialist horticultural publishers.
- Experienced growers, for practical context.
A claim stands on the highest rung that supports it. A lower rung can add context, never overrule.
What we don't use
Content farms, pages that exist to sell a product, and AI-written pages. Five blogs repeating each other count as one source, and usually as none.
Conflicting advice
We look for the reason first: variety, climate, container versus ground, indoor versus outdoor. Then we present a range with its context. We never average two numbers that describe different situations.
On the page
Each guide lists its sources at the bottom. Sections drafted with AI keep a note of which sources supported them; editors check those notes before approving the section.