Up Your Gardening Game with Sweet Onions

Up Your Gardening Game with Sweet Onions

For many people in the Panhandle, gardening season begins when the weather warms in spring and nurseries start setting out tomato transplants.   While I understand the allure of the yummy summer veggies and spring/early summer are the most traditional times to garden, cultivating a winter garden in the Panhandle unlocks many tasty options.  Among these cool-season garden veggies is a classic southern staple that is among the easiest and most rewarding of all vegetables to grow, sweet onions!

‘Texas Super Sweet’ Onions almost ready for harvest in a Calhoun County garden. Photo courtesy of Joe Leonard.

Sweet onions are very popular in the culinary world for their mild flavor and soft texture and are among the most widely grown group of onions across the world, but the most famous of them, Vidalia’s, hail from Georgia!  Despite its fame, the “Vidalia” onion is actually nothing more than a trademarked name for a specific variety of sweet onion that was bred in Texas (‘Yellow Granex’ and its derivatives), grown in a 20-county region in South Georgia with excellent onion-growing soil, and made famous by excellent marketing from the Vidalia Onion Committee.  While they can’t be called Vidalias legally, you can absolutely grow your very own Vidalia type sweet onions at home here in the Florida Panhandle!

Sweet Onions are most easily grown at home if purchased in the fall as “sets”.  Sets are small bulbs that have been started, harvested, dried to prevent rotting during storage, and shipped to garden centers ready to be “set” out in home gardens.  Sweet onions may also be grown from seed but take much longer and have a lower success rate.  When browsing onion set varieties for purchase at garden centers or in seed catalogues, make sure to purchase a short-day “Granex” type like “Texas Super Sweet” or similar.   It is critical to remember that sweet onions are classified by how many hours of daylength they require to produce bulbs.  The three classifications are Short, Mid, and Long-Day.  Since sweet onions require cool weather to develop properly, Floridians must grow short-day varieties to compensate for decreased daylight hours in the winter.  In the less hot Northern states, long-day sweet onions are grown in the summer, where they’ll be able to soak up 15-16 hours of daylight.  Therefore, for best results in the Panhandle, select ONLY short-day onion varieties.

‘Texas Super Sweet’ Onions that have been harvested and are ready for use! Photo courtesy of Daniel Leonard.

Once you’ve selected your onion sets in the fall, they can be planted in the garden anytime from early October to mid-December.  Individual bulbs should be planted about an inch deep in well-drained garden soil with high organic matter content (mushroom compost, composted manure, or other rich organic matter works) and spaced 4-6” between plants and about a foot between rows.  Onions in general, and sweet onions in particular, are heavy feeders and require ample nutrition to meet their potential!  To meet these fertility needs, I apply a slow-release fertilizer like Osmocote or a Harrell’s product at planting and supplement that with either a quick release granular or liquid fertilizer monthly during the bulb enlargement phase.  Sweet onions also have a shallow root system and require frequent watering to develop properly and avoid splits, doubles, and small bulbs.  Don’t let your onion bed dry out!

Finally, sweet onions planted in late fall/early winter are normally ready to harvest in April and May.  However, rather than relying on a calendar, begin harvesting your onions when the tops start to turn yellow and fall over, this indicates maturity.  After harvesting, allow your onions to “cure” with tops and roots still attached for a couple of weeks outside in a shaded, protected area.  Once they’ve had an opportunity to “cure”, remove tops and roots and store the cured bulbs in a cool, dry place (a dark pantry in an air-conditioned room or the refrigerator crisper drawer work fine) and use at your convenience!

While they can’t be called Vidalias, sweet onions grown at home are oh so rewarding and very tasty!  Provided they are planted in quality soil, receive plenty of water and fertilizer, and are harvested/stored correctly, sweet onions will provide a delicious, home-grown culinary treat throughout the year!  For more information about growing onions in the home garden or any other horticultural/agricultural topic, contact us at the UF/IFAS Calhoun County Extension Office.  Happy Gardening!