What does the Finnish word "tarha" mean?

A student of mine asks: 

I keep seeing the word "tarha" at the end of longer words: puutarha, eläintarha, lastentarha. What does "tarha" mean? 

 Here's a list of words ending in tarha with their translations to English: 

puutarha - garden
hedelmätarha - orchard
omenatarha - an orchard with mainly apple trees
mehiläistarha - bee farm
lastentarha - day care center or kindergarten
eläintarha - zoo

If you look at the list, you might see that the words all have something in common (besides ending in tarha). These words all mean enclosed spaces that contain something specific: trees (puu), fruit (hedelmä), apples (omena), bees (mehiläinen, mehiläis-), children (lapsi, lasten), animals (eläin). 

Tarha used all on its own usually means lastentarha, so a day care center or kindergarten. 

Lately, I've been spending a lot of time in Malminkartanon omenatarha, or the apple orchard in Malminkartano, where I also took the background picture: