When I first started at my facility there was only one volunteer, now there are ten individuals and five groups and this is not to mention children that come in with their Catholic Education Classes or Boy/Girl Scout Groups. I reached out to everyone when I got hired; religious groups, high schools, posted volunteer signs in adult communities, and contacted facilities around mine for any information they could share. Finally people started calling and I would get right back to them and make appointments and make sure they had all of the paperwork and information they needed in order to start.
After they came or donated I would sit down with the residents and they would make pictures or other art projects for the volunteers and I would send them to them. Many of the volunteers see now how much it meant to the residents and they continue.
My advice to you is to thank you the volunteers with pictures, words, cards, everything, and anything.
Also I send the volunteers monthly a calendar of events to keep them informed.