When we had actual farmers, and not agribusinesses, the farmers would work a plot of land until it was time for the land to lie low and gather its strength (minerals and other plant nutrients) back into the soil. I feel like that plot.
I also think that a fallow “period” is perfect for a writer (of English, at any rate). Not only is it is an unspecified length of time, it’s the punctuation mark that signifies the end of a complete thought. Once upon a time, there was one space in between typed words, and two spaces in between sentences, occurring immediately after the period. A perfect place to lie low.
A “period” also refers, of course, to women’s ovulation cycles, the times when women are fertile, and when they’re not. Just as the skin of the earth and the womb of a woman, so too does an imagination have periods where it is rich and ripe, and periods where it is empty and must rest. Whether we let it rest, or not, is up to us.
These sorts of times are not abnormal periods for me, but they can be frustrating. I feel I must work, work, work. Do, do, do! (“deh-da-da-da,” goes the Police song…) And the truth is (I work to remind myself), these fallow periods, these times of lying low, are absolutely crucial to the continued, long-term success of any endeavor, no matter the creative vein.
Hooray for creatively invigorating periods of non/low activity!
Aaaaand…now back to work. 
