Read a cpl quick google searchs , one guy had it done without isolating his plants and they all died..
I don't know what chemical they use, but unless its an inert gas like co2, Its going to harm ya plants im pretty sure.
Fumigation Process
Fumigation eliminates termites in the structure, not the colony hidden in the soil below. After tenting the entire structure, fumigants, such as sulfuryl fluoride, fill the space to kill off termites. This tenting only covers the structure; outdoor garden plants are not in danger. Indoor plants should be removed before fumigation starts, however, because they could be killed from chemical exposure. When the tent is removed, any residual fumigants should float upward into the atmosphere. Professional fumigation workers should be careful around your garden during tent removal so that fumes are not released to the sides, but are directed upward to avoid foliage damage.
http://homeguides.sfgate.com/can-termite-fumigation-kill-garden-83034.html