Green Onions in Zone 10B — Florida

Green onions are a fantastic addition to any Florida garden. Their mild, fresh flavor elevates everything from grilled fish to summer salads. Plus, they're incredibly easy to grow, providing a steady supply of tasty greens almost year-round.

Our Florida gardening calendar is different, and while the summer heat can be tough on many crops, green onions thrive when planted in fall for a winter harvest. With our long, 360-day growing season, you can enjoy fresh green onions for months with the right timing.

You can transplant green onions outdoors from early December through early January. This gives them a good start before the heat of late spring arrives. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

When transplanting, space the seedlings 2-3 inches apart. Be mindful of potential temperature swings during this time of year, and protect young transplants from unexpected cold snaps.

Direct sowing is the preferred and easiest method for growing green onions here in Florida. You can direct sow from early December through mid October, giving you almost year-round planting opportunities. Soil temperatures between 60-70°F are ideal for germination.

Prepare your soil by loosening it and adding compost to improve drainage and fertility. Sow seeds about ½ inch deep and 2-3 inches apart. You can also plant the root ends of store-bought green onions – just stick them in the soil, and they'll regrow!

Green onions need consistent moisture to produce those tender, mild stalks we love. Here in Florida, that means paying close attention, especially since our sandy soil drains quickly. Keep the soil consistently moist, but not waterlogged.

During the cooler, drier months (fall through spring), aim for about 1 inch of water per week, supplementing rainfall as needed. In the wet-summer, you might not need to water as frequently, but always check the soil moisture first. Stick your finger about 2 inches deep – if it feels dry, it's time to water. It's best to water at the base of the plants to avoid creating a humid environment around the leaves, which can encourage fungal diseases.

Signs of underwatering include wilting and yellowing leaves. Overwatering can lead to root rot, indicated by soggy soil and stunted growth. A layer of mulch, like pine straw or shredded leaves, will help retain moisture and suppress weeds.

Your first harvest of green onions can be expected from early February through early January, about 60 days after planting. The best time to harvest is when the stalks are about pencil-thick.

You have a couple of options for harvesting. You can pull the entire plant, or you can cut the stalks about an inch above the base. If you cut them, the green onions will often regrow, giving you multiple harvests. As late December approaches and our first frost looms, harvest any remaining green onions to use or preserve.

Here are some common problems you might encounter with green onions in Florida:

Onion Maggots

• What it looks like: Wilting or yellowing plants, stunted growth, and small white maggots feeding on the roots and bulb.
• What causes it: These pests thrive in moist soil conditions.
• How to fix/prevent it: Use row covers to prevent adult flies from laying eggs. Introduce beneficial nematodes to the soil.

Thrips

• What it looks like: Silvery streaks or white patches on the leaves, distorted growth, and tiny, slender insects on the plants.
• What causes it: Thrips are attracted to dry conditions and can become a problem during our drier periods.
• How to fix/prevent it: Increase humidity by watering regularly. Insecticidal soap can help control infestations.

Downy Mildew

• What it looks like: Yellow patches on leaf tops with fuzzy gray-purple growth on undersides. Leaves brown and die from the bottom up.
• What causes it: Oomycete pathogen that spreads in cool, humid conditions via wind-carried spores.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation. Water at the base, never overhead. Copper-based fungicides for prevention.

Pink Root

• What it looks like: Roots turn pink or reddish, plants are stunted, and leaves may yellow.
• What causes it: A soilborne fungus that thrives in warm, wet conditions.
• How to fix/prevent it: Improve soil drainage, practice crop rotation, and use nematode-resistant varieties.

Florida Specific Challenges: The extreme humidity and wet-summer rainfall in Florida create ideal conditions for fungal diseases like downy mildew and pink root. Our sandy soil and nematode populations can also stress plants, making them more susceptible to pests and diseases.

Companion planting can help your green onions thrive. Carrots are great companions because they deter onion flies, while the onions deter carrot flies. Lettuce provides ground cover, helping to keep the soil cool and moist. Tomatoes and peppers benefit from the onion's pest-repelling properties. Beets also make good companions, as they don't compete for the same nutrients.

Avoid planting green onions near beans or peas, as they can inhibit each other's growth.