Plant Heritage has a number of sister organisations across the world, why not go and see what they have to offer? (click on the logos to go to the website)
The Garden Plant Conservation Association of Australia is based at the Royal Botanic Gardens, Melbourne and has an informative blog here.
in France, has many collections and is quite heavily involved in Courson, the French equivalent of the Chelsea Flower Show, they publish a magazine 'Hommes et Plantes'
The German organisation Netzwerk Pflanzen sammlungen in Germany, has a brilliant website with lots of information. They have only been active since 2009/2010 so do go and offer support!
The Dutch National Plant Collections
are part of the Dutch Botanic Gardens Federation and their goal is to create a 'National Plant Collection' held cooperatively through the botanic gardens. They therefore try to avoid duplication of collections.
The Nederlandse Planten Collecties are by contrast held almost exclusively by commercial nurseries as reference collections. They have been in existence since 1995 and have around 100 collections. They are an initiative of the Koningklijke Vereniging van Boskoopse Culturen (KVBC) the Dutch Royal Horticultural Society.
The North American Plant Collections Consortium
, adminstered throught the American Public Gardens Association has collections in institutional partners such as botanic gardens, university gardens and large public gardens.They have 64 participating gardens, 60 single site, and 3 multi-site collections.