Growing onions in Florida presents a challenge due to the state’s mild winters and intense summers. Success requires adopting techniques tailored to the subtropical environment, moving away from traditional gardening practices. Understanding the specific daylight needs of the onion plant and Florida’s sandy soil composition is the foundation for cultivating these bulbs. Success relies on precise timing and specialized care to nurture the crop through the cooler months before the summer heat arrives.
Selecting the Ideal Onion Type for Florida
The most important decision for a Florida onion grower is selecting a “short-day” variety, dictated by the state’s southern latitude. Onions are classified based on the number of daylight hours needed to trigger bulb formation. Short-day onions initiate bulbing when the day length reaches approximately 10 to 12 hours, which occurs during the state’s winter season.
Attempting to grow “long-day” varieties will result in thick-necked plants that never form a proper bulb because the necessary 14 to 16 hours of daylight only happens during Florida’s summer heat. Suitable short-day varieties include ‘Granex,’ the parent cultivar for Vidalia onions, ‘Texas Grano 1015Y,’ and ‘Red Creole.’ These varieties are naturally sweeter and have a higher water content, meaning they typically have a shorter storage life compared to long-day counterparts.
Timing and Preparing for Planting
The correct planting window is crucial to ensure the plants mature before the onset of summer heat. Gardeners should plant onions during the late fall or early winter, typically spanning from September through December, depending on the location. This timing allows the plants to establish a strong root and leaf system during the cool season.
Starting with transplants or sets (small dormant bulbs) is preferred over direct-seeding, as it significantly shortens the time to harvest. Plant the small bulbs about an inch deep into the soil, leaving the neck exposed, and space them four to six inches apart. Florida’s native sandy soils drain well, which is beneficial since onions are intolerant of waterlogged conditions. However, this soil is naturally low in organic matter and nutrients. Before planting, incorporate generous amounts of compost or well-rotted manure to improve fertility and water-holding capacity, and consider using raised beds to ensure optimal drainage.
Ongoing Care and Maintenance
Consistent moisture is necessary for the development of large, healthy onion bulbs, but the plant’s shallow root system requires careful irrigation. The sandy soil necessitates frequent watering to maintain moisture without saturation. Aim to provide about one inch of water per week, adjusted for rainfall, and use drip irrigation or soaker hoses to keep the foliage dry and reduce the risk of fungal disease.
Onions are heavy feeders and require regular fertilization, especially nitrogen, to promote vigorous leaf growth. Apply a balanced fertilizer at planting time, followed by a high-nitrogen fertilizer every three to four weeks during the vegetative growth phase. Stop applying nitrogen once the bulb-forming process has clearly started, as continued nitrogen encourages foliage growth at the expense of the bulb. Pests like thrips can be managed using insecticidal soap or neem oil. Ensuring good air circulation and practicing crop rotation help prevent common diseases like purple blotch.
Harvesting and Curing
Knowing the exact time to harvest is indicated when the onion tops, or necks, begin to turn yellow and naturally fall over. This folding action signals the end of the bulbing process and cuts off the nutrient supply from the leaves to the bulb.
Stop watering the plants completely once the tops have started to fall over to prevent rot and maximize storage potential. On a dry day, gently pull the onions from the ground and allow them to field-cure for one to two days. Curing is the crucial step that prepares the onions for long-term storage by drying the outer skin and neck. Move the bulbs to a warm, dry, and shaded area with excellent ventilation, such as a covered porch, for two to three weeks. Proper curing is complete when the necks are tight and dry, and the outer skin is papery; at this point, the roots and tops can be trimmed before the onions are stored in a cool, dark, and dry location.