Rosemary in Zone 8B — Southeast

Rosemary is a must-have herb in any Southeastern garden. Its distinctive flavor elevates everything from grilled meats to roasted vegetables, and its fragrant foliage is a joy to brush against. Plus, the satisfaction of snipping fresh rosemary sprigs for your favorite recipes, even during our long summer, is hard to beat.

Now, we all know the Southeast comes with its own set of gardening challenges – namely, humidity and clay soil. But with the right timing and a little attention, you can absolutely grow thriving rosemary here. Our 255-day growing season gives you plenty of time to get it established.

Starting rosemary from seed indoors is definitely possible, but it can be a bit finicky. If you're up for a challenge, begin in late December through mid January, giving the seedlings about 12 weeks to grow before transplanting. Use seed trays with a good seed-starting mix, provide warmth (a heat mat helps), and ensure plenty of light with grow lights.

Don't forget to water from the bottom to avoid damping off! Rosemary germination can be erratic and growth is slow, so be patient. Given our moderate spring here in the Southeast, starting with established plants from a local nursery is often the more reliable route.

Transplant your rosemary seedlings outdoors in late March through mid April, after the last expected frost. Before planting, be sure to harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space your rosemary plants 24-36 inches apart to allow for good air circulation, which is crucial in our humid climate. While we're usually past the danger of frost by this point, keep an eye on the weather forecast, as we can sometimes get a late cold snap. Given rosemary's slow growth from seed, consider starting with a healthy, established plant from a local nursery.

Watering is where many Southeastern gardeners run into trouble with rosemary. While it's drought-tolerant once established, our hot, humid summers and frequent rainfall can easily lead to overwatering and root rot. The key is to let the soil dry out between waterings.

Stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. A good rule of thumb is to aim for about 1 inch of water per week, including rainfall. Water at the base of the plant to avoid getting the foliage wet, which can encourage fungal diseases in our humid climate.

Signs of underwatering include wilting and yellowing leaves. Overwatering, on the other hand, can cause root rot, indicated by droopy, dark green leaves. A layer of pine straw mulch around the base of the plant can help retain moisture in the soil during dry spells, but be careful not to pile it up against the stem, as this can also contribute to rot.

Rosemary needs minimal pruning, but a little shaping keeps it looking its best. Lightly prune after flowering to maintain its shape and encourage bushier growth. Avoid cutting into old, woody growth, as it may not regrow.

The best time to shape your rosemary is in the spring. As our first frost usually arrives around mid- November, there's no need for any special end-of-season pruning. Just let it be!

You can start harvesting rosemary in late June through early August, about 90 days after transplanting. Look for stems that are about 4-6 inches long. These are the most flavorful and tender. Avoid harvesting woody stems, as they tend to be too tough to eat.

When harvesting, take stem tips and never remove more than 1/3 of the plant at a time. This ensures continued production throughout our long summer. Rosemary is a continuous harvest plant, so you can snip off what you need whenever you need it.

As our first frost approaches in mid- November, you can continue to harvest as needed. You can also dry or freeze any excess rosemary to use throughout the winter months.

Here are three common problems you might encounter growing rosemary in the Southeast:

Root Rot from Overwatering

• What it looks like: Droopy, dark green leaves, often accompanied by a musty smell in the soil. The plant may appear stunted or fail to thrive.
• What causes it: Overwatering and poor drainage create soggy conditions that suffocate the roots, leading to fungal rot. Our wet-summer rainfall and humid climate exacerbate this issue.
• How to fix/prevent it: Ensure well-draining soil. Amend heavy clay soil with compost and consider growing rosemary in raised beds or containers. Water only when the top 2 inches of soil are dry. Avoid overhead watering.

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: Various fungi that thrive in warm days, cool nights, and moderate humidity – conditions we often experience in the Southeast. Surprisingly, dry leaf surfaces actually favor powdery mildew.
• How to fix/prevent it: Improve air circulation by spacing plants adequately and pruning to open up the canopy. 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 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 often the best treatment. Increase humidity around plants. Neem oil or insecticidal soap can also be effective.

Southeast Specific Challenges: Our hot, humid summers and wet-summer rainfall create a perfect storm for fungal diseases like root rot and powdery mildew. Good air circulation, well-draining soil, and careful watering are essential for success.

Rosemary thrives when planted near certain companions. Sage, thyme, and lavender all enjoy similar growing conditions – full sun and well-drained soil – and their aromatic oils can help deter pests. Green beans and carrots also benefit from rosemary's presence, as it can help repel bean beetles and carrot rust flies.

Avoid planting rosemary near mint. Mint is vigorous and invasive, and can quickly crowd out rosemary and steal valuable resources.