My husband and I visited the orchid garden one afternoon just prior to closing. The garden is a collection of orchids attached to trees or under a greenhouse with winding cement pathways. While small, they have around 400 different types of orchids. Not all of these are in bloom at the same time however- during our trip we probably saw around 100 different flowers.
We took the guided tour which was excellent! Our guide (katelyn?) was very knowledgeable and spoke English very well. The majority of the orchids which were in bloom while we were there were mini orchids- many required a hand held magnifying glass to appreciate the colors and details. I would not have enjoyed the garden nearly as much without the tour, as it is very hard to find some of the blooms when they are so small!
The garden does not take credit cards, however it was only $10 or so per person and well worth it! If you are traveling to monteverde (or anywhere in Costa Rica) you can't expect small businesses to take credit cards.
I would gladly return to the orchid garden!