Columbus (CTZ)

Columbus is a super-alpha hop: a variety with exceptionally high alpha acids, the source of bitterness. According to the American plant patent (PP10956, granted in 1999), it originated from a cross in 1982 in a small hop nursery near Prosser, Washington.

It was an open pollination. Seed from twenty to thirty mother plants was harvested together, while about as many male plants were flowering. The exact parents are therefore unknown. Merchants such as Haas and BarthHaas assume that Columbus has the same mother plant as Nugget; BarthHaas also mentions Brewer's Gold, but as an assumption.

Columbus is often mentioned in the same breath as Tomahawk® and Zeus, together 'CTZ'. According to the variety list of the international hop growers' organisation IHGC, they are three genetically (almost) identical varieties. The American agricultural statistics count them together as one item.

Striking: the patent from the 1990s says that Columbus has a mild, soft aroma, 'without any special character'. Later research shows more. Belgian researchers wrote in 2011 that brewers used Tomahawk, genetically almost identical to Columbus, a lot for bitterness and a citrusy aroma. The variety turned out to be rich in selinenes, methyl geranate and geraniol, a compound with a floral, rosy aroma. It also contained many different thiols, including 3MH and 3M4MP. A follow-up study found a lot of 3-sulfanyloctan-1-ol in beer made with Tomahawk: a compound that can reveal that this variety was used. In a study by researchers from the hop merchant Hopsteiner, with 97 varieties, Columbus fell in the middle category for thiols.

Merchants describe the aroma in different ways: 'vegetal' and spicy, with sweet fruit, flowers and citrus (BarthHaas), 'aromatic, penetrating' (Haas), or black pepper, light citrus and onion (Hopsteiner, about Zeus).

Columbus is first and foremost a bittering hop. The patent gives 14–16% alpha acids, BarthHaas gives 13.9–17.5% for recent harvests and the Belgian researchers 14–18%. BarthHaas also calls it a 'dual purpose' hop that works late in the kettle or in dry hopping, in American ales, IPAs, imperial red ales and lagers.

A drawback is the keeping quality of the hop itself. According to the patent, Columbus lost 60–80% of its alpha acids in six months at room temperature, against 35–45% for Chinook. In 2014 Haas called the keeping quality 'very poor' and wrote that CTZ was losing ground because of it, and because of sensitivity to mildew.

According to Hopsteiner, Zeus is a super-alpha variety from its own breeding programme in the Yakima Valley.

The Columbus patent lists three inventors: Gregory K. Lewis, Charles E. Zimmermann and Henry Hazenberg. It was assigned to HUSA-CEZ LLC; the application had been running since 1993. The patent compares the yield with HopUnion figures from 1992: Columbus gave 3,290 pounds per acre, against 2,216 for Chinook.

Why one hop is sold under three names is hard to follow in public documents. In 2022 the IHGC included 'CTZ' as an official synonym, at the proposal of the Hop Growers of America.

According to the American agricultural statistics, the US harvested well over 6,000 tonnes of CTZ in 2025: well over 16 percent of the total American harvest and more than any other hop variety in those statistics. Citra did stand on more land: about 3,070 against 1,980 hectares.

A good starting point: an IPA or pale ale in which CTZ provides the bitterness. Pay attention to a firm bitterness, with spicy, citrusy or green notes behind it. If you come across CTZ as a late-addition hop or in dry hopping, smell whether you find the citrus that researchers described.

Hop aroma is fragile. So drink hoppy beers fresh and store them cool.