Post a picture and I can probably tell you how old your staghorn is, at least within 6 months.
One obtains Master Gardener certification by taking a course presented in a university setting (at least in Mississipp, where the course was at Mississippi State University). Generally the Extension Service prepares and presents it. Most of the presenters are university professors. After 3 months or so of classes, and then passsing a final exam, Master Gardener status is obtained.
My last two greenhouses were kits, and are built from the gound up. The one previous to these, at another house, was hand-made. My first one, again at another house on Mississippi Gulf coast, was professionally built or brick, marine aluminum framing, and glass. It was a huge 32'x14' greenhouse. A hurricane destroyed it partially in 1985 and then Katrina completely destroyed it.
The last greenhouse I built would probably be considered handicap-friendly. It has two sliding doors that open up to 5' and are approximately 6' high. A wheelchair could easily move through these doors and there is approximately 7' between my wire shelving, making the shelving easily accessible as well.
Geraniums are notorious bottom-leaf droppers. I am always removing brown leaves and dead-heading the spent flower stems.
I can't tell you what killed your air-plant (tillandsia). Cold and over-watering are the two most common causes of air-plant death. There are lots of plants considered "air-plants". Your staghorns are air plants and orchids (epiphytic) and many bromeliads are air-plants as well. The term "epiphyte" is more appropriate than using the "air-plant" term.
