The popular event was due to be held at the end of June.
However, some owners are not comfortable opening their gardens to the public yet, leading to a lack of venues.
An OTA spokesperson said: “It is with sadness that we have to announce that our Secret Garden weekend at the end of June, will not go ahead this year, we are having to cancel.
“Unfortunately, because of the current situation, a lot of our garden owners are reluctant to open their gardens to the public this year, and we at the OTA understand and support their decisions.
“We will be back bigger and better, and most importantly, safe next year.”