The best time to plant a tree was 20 years ago. The second best time is now.
The real story
Despite widespread attribution to Chinese wisdom, no credible evidence connects this saying to traditional Chinese proverbs. The "Chinese proverb" label only appeared in a Nebraska newspaper in 1985 — far too late to authenticate ancient origins — and linguists and proverb scholars have failed to find any equivalent in classical Chinese texts. The earliest strong English match found by Quote Investigator appeared in a 1967 Cleveland Plain Dealer article, where city councilman George W. White cited it as an anonymous remark. Earlier structural variants (using different time frames like "30 years ago" or "80 years ago") circulated in Canada and the US from the 1950s onward. The true author remains unknown; the Chinese attribution is unsupported.