Rosemary in Zone 10A — Florida

Rosemary is a must-have for any Florida gardener. Its distinctive flavor elevates everything from grilled meats to roasted vegetables, and the fragrant foliage is a joy to brush against as you tend your garden. Plus, it's a beautiful, drought-tolerant shrub that thrives in our sunny climate.

Our Florida gardening calendar is different, and summer is definitely the slow season. But don't let the humidity and potential for fungal diseases scare you off. With careful timing and attention to watering, you can enjoy fresh Rosemary from your garden for much of our 355-day growing season.

Starting Rosemary from seed indoors is possible, but honestly, it can be a bit of a pain. Rosemary seeds are known for erratic germination, and the seedlings grow slowly. You might want to consider this option if you're after a specific variety that's hard to find as a transplant.

If you decide to give it a try, start your seeds indoors from late October through mid November, about 12 weeks before you plan to transplant. Use seed trays with a good seed-starting mix, and provide warmth and plenty of light. Bottom watering is key to prevent damping off. Remember, spring is reversed here in Florida, so you're starting seeds when most of the country is winding down.

For best results, I highly recommend buying established Rosemary plants from a local nursery. It's just simpler. But if you've started your own seedlings (or found some online), transplant them outdoors from late January through mid February.

Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Choose a sunny spot with well-drained soil, and space your Rosemary plants 24-36 inches apart. Even in late January, we can still get some unexpected temperature swings here, so keep an eye on the forecast and protect your young plants if necessary.

Watering is where many Florida gardeners go wrong with Rosemary. Once established, Rosemary is very drought-tolerant and prefers dry conditions. Overwatering is a surefire way to kill it, especially with our humidity.

During our drier months from late fall through early spring, water deeply about once a week, giving the soil a good soak. Use the "finger test" – stick your finger about 2 inches deep into the soil. If it's dry, it's time to water. Aim for about an inch of water per week, either from rain or irrigation. During our wet summer months, you probably won't need to water at all unless we're in a drought. Always water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our humid climate.

Signs of underwatering include wilting leaves and dry, brittle stems. Overwatering, on the other hand, can lead to yellowing leaves and root rot. A layer of pine straw mulch around the base of your Rosemary plant will help conserve moisture and suppress weeds, but be sure to keep the mulch away from the stem to prevent rot.

Rosemary needs minimal pruning. The main goal is to maintain its shape and encourage bushier growth.

Prune lightly after flowering, which usually happens in spring. Just trim the tips of the branches to encourage new growth. Avoid cutting into old, woody stems, as they may not regrow. Shaping is best done in spring, after the heaviest bloom. As our first frost approaches around late December, there's no specific end-of-season pruning needed; Rosemary is semi-hardy and can handle our mild winters.

You can start harvesting Rosemary from late April through early June, about 90 days after transplanting. Look for 4-6 inch stem tips with healthy, green needles.

Harvest by snipping off the stem tips with clean scissors or pruners. Never take more than 1/3 of the plant at a time, as this can weaken it. The 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.

As our first frost approaches in late December, you can still harvest Rosemary as needed. The flavor may be a bit more intense in the cooler months.

Even Rosemary, with its tough reputation, can face challenges in Florida. Here are the top three problems I see:

Root Rot from Overwatering:

• What it looks like: Yellowing leaves, wilting, and a general decline in plant health. The roots will be brown and mushy.
• What causes it: Soggy soil and poor drainage, combined with our high humidity. Overwatering is the biggest culprit.
• How to fix/prevent it: Ensure your Rosemary is planted in well-drained soil. Water deeply but infrequently, allowing the soil to dry out between waterings. Avoid overhead watering. If root rot is advanced, you may need to dig up the plant, remove the rotted roots, and replant it in fresh soil.

Powdery Mildew:

• What it looks like: A white or grayish powdery coating on the leaves and stems.
• What causes it: Fungal disease that thrives in warm days, cool nights, and moderate humidity. Surprisingly, it likes dry leaf surfaces.
• How to fix/prevent it: Improve air circulation by spacing your plants properly and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays can help. A milk spray (1 part milk to 9 parts water) is also surprisingly effective.

Spider Mites:

• What it looks like: Fine stippling on the leaves (tiny white dots) and fine webbing on the undersides of leaves and between stems. Leaves may 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 spray of water (daily for a week) is the best treatment. Increase humidity around your plants. Neem oil or insecticidal soap can also be effective.

Florida Specific Challenges: Rosemary, while drought-tolerant, really struggles with our consistently high humidity. Good air circulation is key. Even nematode-resistant varieties can struggle in our sandy soil, so consider amending with plenty of compost. Watch closely for fungal diseases, especially during our wet-summer months.

Rosemary plays well with other herbs and certain vegetables in the Florida garden. Sage, thyme, and lavender make excellent companions, as they share similar growing requirements (full sun, well-drained soil) and can even help deter pests. Green beans and carrots also benefit from being planted near Rosemary, as it can repel bean beetles and carrot rust flies.

Avoid planting Rosemary near mint. Mint is incredibly invasive and can quickly take over your garden, outcompeting Rosemary for resources. Plus, mint prefers moist soil, which is the opposite of what Rosemary needs.