Onion in Zone 8B — Florida

Growing onions in Zone 8B Florida gives you the satisfaction of harvesting sweet, crisp bulbs that put store-bought varieties to shame. Here in Florida, our reversed growing calendar means you'll be planting onions during our pleasant winter months and harvesting through spring and summer when fresh produce prices soar. The long storage life of properly cured onions makes them especially valuable for our hurricane-prone region.

While our extreme humidity and sandy soils present challenges for many crops, onions actually adapt well to Florida's unique climate when you time things right. Our 303-day growing season means you have flexibility in planting dates, and the moderate winter temperatures create ideal growing conditions for bulb development. The key is working with Florida's natural rhythm rather than fighting it.

Starting onion seeds indoors works well in Florida, though it's not the most common approach for home gardeners. If you want the largest possible bulbs or specific varieties not available as sets, start seeds indoors from mid-November through early December, about 10 weeks before transplanting outdoors.

Set up seed trays with quality potting mix and keep them warm (65-70°F) in a bright location or under grow lights. Bottom watering works especially well for onion seeds since it prevents the delicate seedlings from getting knocked over. The controlled indoor environment protects young plants from our sometimes erratic winter weather patterns.

Since Florida's spring comes early compared to northern regions, timing your indoor start correctly is crucial. Start too late and your seedlings won't be ready when outdoor conditions are optimal. Start too early and you'll have overgrown, leggy plants that don't transplant well.

Transplant onion seedlings outdoors from early to late February, when nighttime temperatures stay consistently above freezing and soil begins to warm. Whether you started from seed or bought transplants, the process is the same - just time it right for Florida's growing calendar.

Harden off seedlings gradually over a week by placing them outside for increasing periods daily. Our winter sun can be surprisingly intense, and sudden exposure can shock transplants. Set plants 4-6 inches apart in rows, burying them just deep enough to cover the roots while keeping the growing point above soil level.

February weather in Florida can swing wildly between warm days and chilly nights, so keep row covers handy for unexpected cold snaps. The sandy soil many of us deal with drains quickly, which onions appreciate, but you'll need to stay on top of watering as transplants establish.

Direct sowing onions in Florida works from mid-January through late August, though spring planting gives the best results for bulb development. You can sow seeds or plant onion sets (small bulbs), with sets being much easier for beginners and more reliable in our climate.

Prepare your planting area by working compost into the sandy soil that's common throughout Florida. Onion seeds need soil temperatures around 50-60°F to germinate well, which typically occurs by late January in our zone. Plant seeds ¼ inch deep or sets with their tips just below soil level, spacing them 4-6 inches apart.

Direct sowing later in the season works for green onions, but bulb formation suffers in our hot, humid summers. The intense heat and daily afternoon thunderstorms can stress plants before they have time to develop good root systems. Spring planting remains your best bet for quality storage onions.

Onions need consistent moisture throughout their growing season, which aligns well with Florida's natural rainfall patterns. During the active growing period from February through May, aim for about an inch of water per week, including rainfall. Use the finger test - stick your finger 2 inches into the soil, and water if it feels dry.

Our wet summers actually help onion production, but you'll need to watch for overwatering signs like yellowing leaves or soft bulbs. Water at the base of plants rather than overhead, since our extreme humidity already creates perfect conditions for fungal diseases. Drip irrigation or soaker hoses work exceptionally well for onions in Florida's climate.

As summer progresses and onion tops begin to yellow and fall over, gradually reduce watering. This signals the start of the curing process, and continued heavy watering can cause bulbs to rot. Stop watering entirely once tops are mostly down - our summer heat will naturally cure the bulbs.

A thin layer of organic mulch helps retain moisture during dry spells while keeping soil temperatures more moderate. Avoid thick mulch in Florida's humid conditions, as it can harbor pests and create too much moisture around the bulbs.

Your first onions will be ready from late April through late December, depending on when you planted and which varieties you chose. The classic harvest signal is when the green tops begin falling over and turning brown - this usually happens around 100 days from planting, though Florida's warm conditions can speed things up.

Don't wait for all tops to fall over naturally. Once about 75% have fallen, gently bend over the remaining ones to trigger the curing process. Pull bulbs on a dry, sunny day when possible, brushing off excess soil but leaving the papery outer layers intact. The roots should be well-developed and the neck area should feel firm.

Cure onions in a warm, well-ventilated area for 2-3 weeks before storing. Florida's summer heat works perfectly for this if you have good air circulation - a covered porch or garage with fans works well. Properly cured onions will have completely dry necks and rustling outer skins.

With our mid-December first frost date, you have plenty of time for a full onion season. Late-planted onions may still be sizing up when cooler weather arrives, but they'll keep growing through our mild winters as long as they're established before the heat of summer.

Onion thrips appear as tiny, slender insects that cause silvery stippling on leaves, eventually leading to brown, papery foliage. These pests thrive in our hot, dry conditions and can quickly overwhelm plants during Florida's intense summer months. Control them with reflective mulch around plants, beneficial insects like predatory mites, or targeted spraying with insecticidal soap during cooler morning hours.

Pink root shows up as pink to reddish roots that eventually turn dark and rot, stunting plant growth and reducing bulb size. This fungal disease flourishes in Florida's warm, humid soils, especially when drainage is poor or plants are stressed. Prevent pink root by improving soil drainage with raised beds, rotating onion family crops to different areas each year, and choosing resistant varieties when available.

Bolting occurs when onion plants send up flower stalks prematurely, making the bulbs small and bitter. Florida's fluctuating winter and spring temperatures can trigger this response, especially during warm spells followed by cool snaps or when plants experience drought stress. Prevent bolting by maintaining consistent moisture, choosing appropriate varieties for our climate, and providing some afternoon shade during unexpectedly warm periods.

Florida's extreme humidity and frequent summer thunderstorms create additional challenges for onion growing. The combination of heat and moisture can accelerate fungal diseases, while our sandy soils may not provide enough consistent nutrition for optimal bulb development. Success comes from timing plantings with our climate patterns and staying vigilant about drainage and air circulation.

Onions make excellent companions for carrots, beets, lettuce, and tomatoes in Florida gardens. The strong scent helps repel aphids, carrot flies, and other pests that commonly trouble these crops in our humid climate. Carrots and onions particularly benefit each other - onions deter carrot rust fly while carrots help break up compacted soil for onion root development.

Avoid planting onions near beans and peas, as these legumes can be inhibited by compounds onions release into the soil. In Florida's intense growing conditions, this competition becomes more pronounced and can significantly reduce yields of both crops. Instead, use onions as border plants around your main vegetable beds where they'll provide pest protection without interfering with sensitive companion plants.