For his "Off the Charts" segment on Mad Money this week, Jim Cramer talked with Carley Garner, an expert on trading currencies and commodities who's the co-founder of DeCarley Trading.

Garner's been looking at the euro for a long time, and a combination of factors have her thinking that the long, boring period of trading may be about to end.

First the the challenges: U.S. Treasury notes pay higher rates than you can get in Europe. Right now if you were to buy 10-year U.S. Treasurys, you'd get a 2.4% yield. The German 10-year, though, is at 0.4%. And 2-year and 5-year German bunds still have negative yields -- meaning if you buy these pieces of paper, you're literally paying Angela Merkel for the privilege of lending her government money.

In addition, the Fed has launched a series of rate hikes, while the ECB is still only in tapering mode.

So, as long as Europeans want to buy dollars to access higher rates in the U.S., the greenback will benefit.

However, Garner argues that most of those assumptions have already been baked into investor assumptions about the euro. In fact, she believes the euro is forming a base here, meaning it's gaining adherents as it trades sideways and possibly preparing for a rally.

Longer-term, she thinks the euro's prospects look pretty rosy

Even short-term there are some seasonal factors that could give the common currency the boost it needs to break out of its slump. Take a look at this seasonal chart of the euro based on data from Moore Research Center Inc.

The picture shows how the euro has tended to perform in an average year based on the last 15 years. And Garner points out that what we see here is that the euro has a very strong tendency to rally from March through April and early May. Specifically, in 13 of the past 15 years, the euro has rallied from April 13 through May 4, which is a pretty stunning 87% win percentage. That doesn't necessarily mean it's going to happen again this year, but this kind of seasonal pattern nevertheless deserves to be respected. Plus, Garner thinks that the downside risk for the euro is very limited here -- $1.08 buys you one euro -- while the upside potential is wide open.

If, like Cramer, you believe the euro is going up, there are a couple of ways he suggests to play it. The safest way is with the [Guggenheim CurrencyShares Euro Trust]  (FXE - Get Report) , the ETF that reflects the euro-to-dollar exchange rate.

Another alternative is to buy American companies that do a lot of business in Europe, because when the euro gets stronger their European earnings translate back into more dollars, and their products become comparatively cheaper versus the homegrown European competition. Alphabet/Google   ( GOOGL - Get Report)  ,  may be the best bet, given its large business in Europe.