French marigolds are not frost-hardy but will continue to grow ... Water early to allow foliage to dry before nightfall and remove damaged leaves. Wilting of the entire plant can be an indication ...

However, severe cold conditions and early frost could kill them ... seedlings are ready to transplant without suffering cold ...

The name of the marigold flower ... A “hard frost” is when temperatures drop below 32℉ for an extended period, and causes significant plant damage. Source: Michigan State Extension Center.