Longitudinal evidence is essential for urban tree sponsorship schemes, especially evidence about survival and care over several summers. Yet urban tree sponsorship schemes also need formal responsibility: one coordinator, transparent scheduling and a short common report can prevent voluntary energy from masking repeated failures.

The value of urban tree sponsorship schemes lies in participants shaping the activity themselves. I would protect resident involvement by limiting institutional controls around urban tree sponsorship schemes; immediate enthusiasm is not proof, but it can create the relationships from which durable learning develops.

Evaluation of urban tree sponsorship schemes becomes misleading when it reports only an average. The issue of wealthier streets attracting more sponsors requires separate evidence about who can attend, who supplies hidden labour and who needs additional support to participate.

I would not judge urban tree sponsorship schemes from their launch figures. The real test is survival and care over several summers, observed over several months and including withdrawals. For urban tree sponsorship schemes, clear safety boundaries are compatible with resident involvement and do not require a large administrative structure.