Rosemary in Zone 10B — Florida

Rosemary is a must-have herb for any Florida gardener. Its distinctive flavor elevates everything from roasted vegetables to grilled meats, and the fragrant foliage is a joy to brush against as you walk through your garden. Plus, growing your own herbs is incredibly rewarding, especially when you can harvest fresh sprigs year-round in our forgiving climate.

While our humid summers and sandy soil can pose challenges, rosemary is surprisingly well-suited to Florida's 360-day growing season. With a little attention to watering and well-draining soil, you can enjoy a thriving rosemary plant that adds both beauty and flavor to your garden.

Starting rosemary from seed indoors is possible, but honestly, it's not the easiest route here in Florida. Rosemary seeds can be slow and erratic to germinate, and the seedlings grow slowly. But, if you're up for the challenge, starting indoors gives you a head start, especially if you want a specific variety not commonly found as transplants.

If you decide to start from seed, sow them indoors mid October through early November, giving you about 12 weeks to get them ready for transplanting. Use seed trays with a well-draining seed-starting mix, provide warmth (a heat mat helps), and ensure they get plenty of light – a grow light is essential. Bottom watering helps prevent damping-off, which can be a problem in our humid environment. Remember, our spring is reversed, so getting a head start indoors is key.

Transplanting rosemary outdoors is best done mid January through early February. Before you plant, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sunshine and temperatures.

Space your rosemary plants 24-36 inches apart to allow for good air circulation, which is crucial in our humid climate. Keep an eye on the weather; even though we're past our typical frost window, temperature swings can still happen, so be ready to cover your young plants if needed. Honestly, buying an established plant from a local nursery is the easiest way to get a jump start.

Rosemary is drought-tolerant once established, which is a huge plus for Florida gardeners. Overwatering is a much bigger threat than underwatering, especially with our sandy soil and wet summers. Remember, rosemary prefers dry conditions, so err on the side of caution.

During the cooler, drier months (late fall through early spring), water thoroughly when the top 2 inches of soil feel dry to the touch. Use the "finger test" to check. Usually, about 1 inch of water per week is sufficient, but adjust based on rainfall. In the hot, humid summer, be extra careful not to overwater. Our frequent summer rains often provide enough moisture, so you may only need to supplement during extended dry spells. Always water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our humid environment.

Signs of underwatering include wilting or drooping leaves. Overwatering can lead to yellowing leaves and root rot. Mulching around your rosemary plant with pine straw or wood chips helps retain moisture in the soil and suppress weeds, but be sure to keep the mulch away from the stem to prevent rot.

Rosemary requires minimal pruning, which is great for low-maintenance Florida gardens. The key is to prune lightly after flowering to maintain its shape and encourage bushier growth. Avoid cutting into old, woody stems, as they may not regrow.

Shape your rosemary plant in the spring after the heaviest bloom. Snip off the tips of the branches to encourage new growth. As our first frost usually arrives around late December, give your rosemary a light trim to remove any dead or damaged growth before then.

You can start harvesting rosemary mid April through late May, about 90 days after transplanting. Look for 4-6 inch stem tips. These are the most flavorful. Harvest by snipping off the stem tips with clean pruning shears. Never take more than 1/3 of the plant at a time to ensure continued growth.

Woody stems are too tough to eat, so stick to the newer growth. Rosemary is a continuous harvest plant, meaning you can harvest it throughout the growing season. To encourage bushier growth, regularly harvest the tips of the branches. As our first frost approaches in late December, harvest any remaining sprigs you want to use or dry before the cold weather sets in.

Here are the top 3 problems you might encounter with rosemary in Florida:

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting despite adequate watering, and a general decline in plant health. The roots will be brown and mushy.
• What causes it: Overwatering, poorly draining soil, and our high humidity create the perfect conditions for root rot fungi to thrive.
• How to fix/prevent it: Plant in well-draining soil and avoid overwatering. Ensure your pot has drainage holes. Water only when the top 2 inches of soil are dry. Improve soil drainage by adding sand or perlite.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves and stems. Leaves may curl, yellow, and eventually die.
• What causes it: Fungi thrive in warm days, cool nights, and moderate to high humidity. Surprisingly, dry leaf surfaces actually favor it.
• How to fix/prevent it: Improve air circulation by spacing plants properly and pruning. Remove affected leaves promptly. Apply neem oil or potassium bicarbonate sprays. A milk spray (1 part milk to 9 parts water) can also be effective.

Spider Mites

• What it looks like: Fine stippling on leaves (tiny white dots). Fine webbing on leaf undersides and between stems. Leaves turn bronze or yellow.
• What causes it: Tiny arachnids that thrive in hot, dry conditions. Populations explode during periods of drought stress.
• How to fix/prevent it: A strong water spray (daily for a week) is the best first treatment. Increase humidity around plants. Apply neem oil or insecticidal soap.

Florida Specific Challenges: Our hot, humid summers and wet-summer rainfall create a perfect storm for fungal diseases and root rot. Be vigilant about watering, ensure good air circulation, and choose well-draining soil. Our sandy soil, while well-draining, doesn't hold nutrients well, so amend it with compost regularly.

Rosemary benefits from being planted near certain companions. Sage, thyme, and lavender all share similar growing requirements (full sun, well-draining soil, low watering) and can create a harmonious herb garden. Green beans and carrots also make good companions; rosemary is said to deter bean beetles and carrot rust flies.

Avoid planting rosemary near mint. Mint is aggressive and can quickly take over, crowding out rosemary and competing for resources. Plus, mint prefers consistently moist soil, which is the opposite of what rosemary needs.