Grand Canyon Sweet Onions - August 18, 1999
Jeff Schalau, County Director, Agent, Agriculture & Natural Resources
Arizona Cooperative Extension, Yavapai County
There is still time to break out the seed catalogs and plan a fall garden. Consider chard, lettuce, spinach, radish, turnips, cabbage, cauliflower, kale, and please, don=t hold the onions. Onions are an excellent fall crop for the Verde Valley. For a real treat, grow some sweet onions. You don't have to farm in Vidalia, Maui, or Walla Walla for the real thing. In fact, Arizona producers are now growing Grand Canyon Sweet Onions. Let=s discuss where sweet onions came from and how we can grow them in our backyards.
It all started in 1898 when Bermuda onion seed was planted near Cotulla, Texas. Most of this Bermuda onion seed came from the Canary Islands. As the demand for seed increased, the quality declined. This prompted Texas onion growers to investigate other varieties. The Grano variety was imported from Spain in 1925. Texas A & M University began an onion breeding program in 1933. These breeding efforts continued until 1942, when the Early Texas Grano 502 was released. It is a large, broad-bulbed onion that matures early, is of uniform size, and has a mild, sweet flavor.
Next, a hybrid between the Grano and Bermuda was developed and released in 1952. This was called Granex. We also know this onion as the Vidalia. This came about when some transplants were sent to Georgia for planting. When they were tasted, the word spread like wildfire about these new sweet onions from Vidalia. Today, 225 growers cultivate Vidalia onions on 14,000 acres. The crop brings $50 million directly into Georgia's economy each year and economic impacts from related downstream marketing activities are estimated to bring in $145-$150 million yearly.
Texas A & M University later developed the Texas Grano 1015Y. This is the most common Texas sweet onion grown today and the seed source for the Grand Canyon Sweet Onion: the official sweet onion of Arizona. The seeds are available from many different suppliers. These sweet varieties have a lower sulfur content and a higher water content. Hence, they have a much shorter shelf life than spicier storage varieties. There are also long day length varieties available. Don't buy these. They are for the northern latitudes (i.e. Walla Walla).
So, how do we make sure our onions are sweet? It's all in the soil, or rather what is not in the soil. All sweet onion growing regions have one thing in common: soil that is deficient in sulfur. The sulfur containing compounds make onions pungent and spicy. Even the sweet varieties mentioned would become spicy when grown in sulfur rich soils. So, if you want them sweet, don't use ammonium sulfate, soil sulfur, or any other sulfur containing fertilizer. Ammonium nitrate, urea, or good old manure will add the needed nitrogen without adding sulfur.
If you can't grow your own sweet onions, Frank Geminden of Windmill Garden in Camp Verde sells a Camp Verdalia onion that is out of this world. If you are really a sweet onion fanatic, go to the Grand Canyon Sweet Onion Festival in Rock Springs (south of Black Canyon City) each May. It's a blast.
The University of Arizona Cooperative Extension has publications and information on vegetable gardening and seed varieties. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at firstname.lastname@example.org and be sure to include your address and phone number.
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