Storing spices against mold I'm storing spices and dried herbs, as I always did, in glass containers into a spice only-drawer. It always worked fine. 
But looks that this house is particularly humid, because ground spices, and even seeds like fennel, started to become moldy, and they're not THAT old...
I don't always have access to new spices, so I must buy them all around once in a year.
Is there amy storage  tip for avoiding mold?
Have you considered vacuum sealing? As you are buying larger amounts of spices to use for a whole year, here's what I would recommend. 

Obtain some vacuum seal containers sized for the amount of each spice you are going to purchase. Get some smaller glass bottles for your daily use.

When you purchase your spices and get them home, fill the small bottles with enough of each spice to last 2 or 3 weeks.

Then vacuum seal the remainder of each spice in the larger containers. 

As you use up the spices in the small bottles, you can refill them from the sealed containers and then reseal them.