Diversity studies relying only on accessions from ex situ collections ignore plant diversity present in natural habitats, especially in remote or politically unstable regions. Ex situ collections have focused on a limited set of widely-grown crops and lack diversity of minor crops, underutilized crops, and crop wild relatives. Geographic priority regions for further collecting include South Asia, Mediterranean, West Asia, Mesoamerica, sub-Saharan Africa, Andes, and East Asia. Breadfruit, bananas, lentils, beans, chickpeas, barley and bread wheat are well-represented in collections, while pearl millet, yams, finger millet, groundnut, potatoes and peas remain underrepresented. Effective conservation of most crop diversity ex situ is feasible if progress continues. Conserving crop diversity and wild relatives provides adaptive resources for breeding and supports food security and sovereignty. However, crop evolution can’t be monitored in static gene bank collections. Integrating in situ, on-farm, and ex situ conservation with recollections, habitat preservation, and core collections could better maintain crop diversity. Open access to collections benefits continued crop improvement, research, and variety development to meet population growth and intensified farming needs while restrictions may reduce use. Policy should consider the contributions and concerns of all parties. Crop conservation differs from wild species conservation in the strong, essential human role. Unlike habitat reserves, crop habitat is the farming unit or community. Humans actively plant, harvest, and control crop plants, affecting their diversity. For non-cultivated crops, humans also control harvest and regeneration intensity. Locally-based crop conservation is key. Plant conservationists and practitioners should develop guidelines for under-addressed conservation areas.