Gardening in Florida: zones, frost dates and when to plant

North, Central and South Florida

UF/IFAS Extension’s Florida Vegetable Gardening Guide (SP 103/VH021) divides the state into three planting regions, using two highways as the boundaries:

• North Florida, everything north of State Road 40. It gets the most frost and freeze damage, so warm-season crops have to wait until the risk of a late frost has passed.
• Central Florida, between State Roads 40 and 70. Frosts and freezes happen occasionally.
• South Florida, below State Road 70. Frost is rare.

NOAA’s state climate summary shows how large the spread is. Average January temperatures range from the low 50s °F in the north to the upper 60s in the south. In July, average temperatures sit in the low 80s nearly everywhere. Most of the rain falls from June through September, often in afternoon and evening thunderstorms, and hurricanes vary widely from year to year.

A fall-to-spring season

The guide says vegetables can be grown year-round in Florida if each crop goes in at the right time. Those times look very different from the North. In South Florida, its planting table puts tomatoes in from late summer through winter, and lettuce, broccoli, cabbage and kale are fall and winter crops in most of the state. North Florida gets a spring planting window plus a shorter late-summer one for crops like tomatoes and peppers.

Both ends of the season carry risk. Crops planted in August or September run into insects and diseases that thrive in heat. Cold-tender crops planted in late winter can be hit by frost unless they’re covered. UF/IFAS also offers a planting tool, Florida Fresh (floridafresh.ifas.ufl.edu), that lists what to plant now for your ZIP code.

Summer: grow for the heat

UF/IFAS Gardening Solutions blames summer heat, seasonal rains and sandy soil for making summer the hard season. Carrots, potatoes, beets and turnips are winter crops in Florida, summer squash struggles, and tomatoes face wilts, pests and humidity. Its list of crops that handle the heat:

• okra, sweet potatoes and southern peas
• Seminole pumpkin and calabaza
• Malabar spinach, amaranth and other tropical greens
• boniato, which is popular in South Florida
• ‘Rattlesnake’ pole beans

For peppers, it names ‘California Wonder’, ‘Red Knight’ and ‘Big Bertha’ as bells that do well in Florida, and St. Augustine’s datil pepper as a local hot pepper. Cherry tomatoes, and heat-tolerant types such as ‘Heat Wave II’ and ‘Sun Gold’, can carry tomatoes into warmer weather.

Summer is also the season for soil care. The guide recommends summer cover crops such as cowpea, velvet bean, sunflower and sunn hemp, and cereal rye, crimson clover or Austrian winter pea in winter.

What limits Florida gardens

Sandy, infertile soil. Most Florida soils are low in organic matter, so UF/IFAS recommends adding compost, rotted leaves, manure or cover crops. Sandy soil also needs watering more often than clay, muck or amended soil. Drip irrigation and micro-sprayers are among the most efficient systems.

Nematodes. These microscopic worms attack roots and cut yields. The guide’s main remedy is soil solarization: clear and wet the soil, then cover it tightly with clear plastic for the warmest six weeks of summer. Organic matter and cover crops like sunn hemp, sorghum and rye also help suppress them.

Pests and disease in the heat. The guide’s variety table marks several tomatoes as resistant to tomato spotted wilt virus, among them ‘Amelia’, ‘Quincy’ and ‘BHN 640’. It notes that leaf lettuces grow well in Florida, while crisphead types should be grown only in the coolest months.

pH extremes. The best pH for vegetables on sandy soil is 5.8 to 6.3, and no adjustment is needed between 5.5 and 7.0. Where limestone, marl or shell makes the soil naturally alkaline, there is no practical way to lower the pH permanently. A fertilizer with micronutrients helps in those soils.

Before you plant

Test first. UF/IFAS points gardeners to the UF/IFAS Extension Soil Testing Laboratory and warns against adding lime the soil doesn’t need. Because some Florida soils already hold enough phosphorus, which pollutes lakes and rivers when it washes off, a soil test also tells you whether a standard 10-10-10 is the right fertilizer. North Florida gardeners should check the frost dates for their city above before setting out tomatoes and peppers in spring.