WHEN TO VISIT
Speaking of best time to go trekking, mountains of Georgia are very similar to those of Europe - best period is from the second half of June till late September. If you are a very busy person, this is all you need to know, but for those more curious, I will try to elaborate.
Caucasus generally gets lots of snowfall (especially its western parts) and winter conditions in mountains remain for the most of the spring. Therefore, ordinary tourists should wait until the second half of May, when also roads to Tusheti and Khevsureti open up. At this period, valleys are already green, but trekking options are still quite limited - there is lots of snow higher in the mountains and many passes are not accessible. One can do many nice day hikes, but tackling mountain passes could be risky.
If you want to do some serious multiday trekking, you should wait till late June - nature is at its best, everything is green and blooming. However, there is a price - May and June are the rainiest months of the year.
In July and August weather becomes more stable and dry - this period is considered to be a “high season” for trekking. Good conditions usually persist for the most of the September, then become gradually worse.
You can have some nice hikes or even treks also in the first half of October if you get lucky with the weather, but one can´t count on it - depends on the date of first serious snowfall.