Trustees at Middleton, the troubled National Botanic Garden of Wales, held a candlelight vigil on Friday night.
Other botanic gardens around the world - in the United States, Western Australia, New South Wales, South Africa,
Germany, Chile, the Canary Islands, Alaska, New Zealand, and India - lit candles in a show of solidarity.
Organisers said the aim of the event was to "rekindle our passion for the future of the garden and let the world know that so many people care".
A beacon was lit to symbolize the flames of the Welsh dragon.
Earlier this week, the closure of the garden was postponed when a last-minute offer of help emerged.
No details about the surprise intervention were revealed, but talks have been taking place and the £43m garden at Llanarthne has been given a few days' stay of execution.
The garden's trustees had been expected to call in administrators on Monday afternoon, after the Welsh Assembly Government refused to provide £3m to bail out the attraction which was suffering from a drop in visiting numbers.
Complex negotiations still lie ahead, but there is now hope the site will be able to stay open.
Trustees at Middleton say they are still considering the offer, made to them moments before the crucial meeting.
They will not reveal the nature of the offer, but they have admitted it could allow the garden to survive in its present form.
The Welsh Assembly Government said it was approached by Middleton's officials this week and asked to reconsider its rejection of the garden's own recovery plan.
But government sources say they have not been given enough new information to change their minds sufficiently to persuade it to offer the financial guarantees requested.