About three (3) times a year you can cut your Zaatar plants to use.
Growing not just Zaatar plants but any herb plant is extremely easy.
After you cut your Zaatar herbs you must wash them in cold water, let them sit for awhile so you can ensure that all, if any, bugs are flushed out.
Ensure that after washing off your Zaatar that the leaves are as dry as they can be.
DO NOT leave too much water on the leaves of the Zaatar or the color will darken/blacken and the taste will diminish.
The best way, in my opinion to ensure that as much water gets removed from the leaves is by utilizing a salad spinner.
Set your Zaatar in a dark room, spread out evenly and temperature ranging from 70-75 degrees F. Ensure that, at least, for the first day that there is air movement in the drying room (a small fan would do).
Then after three (3) days your Zaatar herbs are completely dry.