French Marigold in Zone 8B — Southeast

French marigolds are a fantastic addition to any Southeast garden. Their bright blooms add a cheerful pop of color, they're edible (though more peppery than tasty), and they help deter pests from your precious tomatoes and peppers. Plus, they thrive in our long summer and are fairly drought-tolerant once established.

We definitely have our share of challenges here – humidity, fungal diseases, and those ever-present Japanese beetles. But with a long growing season of around 255 days, you have plenty of time to get these beauties growing strong and blooming before any major problems hit.

Starting French marigolds indoors isn't completely necessary in our region, given our long growing season, but it can give you a head start, especially if you want blooms as early as possible. Start your seeds indoors from early to late February, about six weeks before you plan to transplant them outside.

Use seed trays with a good seed-starting mix, and keep them warm (around 70-75°F) until germination. A heat mat can really help. Provide plenty of light – a grow light is ideal, but a very sunny windowsill can work too. Consider bottom watering to keep the seedlings moist without encouraging fungal issues. The moderate spring start we usually have here gives you a good window to nurture these indoors before the heat really cranks up.

Transplant your French marigold seedlings outdoors from late March through early May, after the last expected frost. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. Start with an hour or two of shade, increasing the time and sun exposure each day.

Plant them 8-10 inches apart in well-drained soil. Keep an eye on the weather; those late-season cold snaps can still happen, so be ready to cover them if needed.

Direct sowing is a perfectly viable option for French marigolds in the Southeast, thanks to our long growing season. Sow seeds directly into the garden from early March through mid September. This gives you plenty of time to get a few rounds of blooms!

Prepare the soil by loosening it and removing any weeds. Sow seeds about ¼ inch deep and 8-10 inches apart. Keep the soil consistently moist until germination, which usually takes about a week. The advantage of direct sowing is that the plants avoid transplant shock.

French marigolds are relatively drought-tolerant once established, but they still need consistent watering, especially during our hot and humid summers. Water deeply but infrequently, allowing the soil to dry out slightly between waterings. A good rule of thumb is to stick your finger about 2 inches deep into the soil; if it feels dry, it's time to water.

During the spring and fall, when temperatures are milder and rainfall is more frequent, you might only need to water once a week, giving them about an inch of water. In the heat of the summer, when we often get afternoon thunderstorms, check the soil moisture more frequently. Even with the rain, the intense heat can dry things out quickly. Aim for about 1-2 inches of water per week, whether from rain or irrigation.

Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our humid climate. Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to root rot, so watch out for yellowing leaves and a mushy base. Mulching around the plants with pine straw or shredded bark can help retain moisture and suppress weeds.

Deadheading is key to keeping your French marigolds blooming throughout our long growing season. Regularly remove spent flowers by snipping them off just below the flower head. This encourages the plant to produce more blooms instead of putting energy into seed production.

You can deadhead anytime you see a faded or dried-up flower. There's no need to prune anything else. As the first frost approaches in mid- November, you can let the last blooms fade and allow the plant to set seed if you want to collect them for next year.

You can expect your first French marigold blooms about 50 days after planting, so from late April through mid November, depending on when you started them. Harvest the flowers when they are fully open and brightly colored.

To harvest, simply snip the stem just below the flower head with scissors or pruning shears. Harvesting regularly will encourage the plant to produce even more flowers. These flowers don't ripen off the vine, so you need to get them when they're ready.

As the end of the season approaches and the first frost threatens, you can either let the last flowers fade and collect the seeds, or you can bring some of the plants indoors to try and extend the bloom time a bit longer.

Here are some common problems you might encounter with French marigolds in the Southeast:

Spider Mites

• What it looks like: Fine webbing on the leaves and tiny, spider-like creatures on the undersides. Leaves may appear stippled or yellowed.
• What causes it: Dry heat. While we have humidity, there can be periods of drier heat where spider mites flourish.
• How to fix/prevent it: Increase humidity around the plants by misting them regularly. Insecticidal soap or neem oil can also be effective.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems, and sometimes fruit. Leaves curl, yellow, and die. Reduces plant vigor.
• What causes it: Various fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it (unlike most fungi). Our humid summers and warm nights create the perfect conditions.
• How to fix/prevent it: Improve air circulation through spacing and pruning. Remove affected leaves. Neem oil or potassium bicarbonate sprays help. Milk spray (1 part milk to 9 parts water) is surprisingly effective. Plant resistant varieties.

Slugs

• What it looks like: Holes in the leaves, especially on young plants. Silvery slime trails on the foliage and surrounding soil.
• What causes it: Slugs love moist, shady conditions. Our frequent rainfall and humid air provide an ideal environment for them.
• How to fix/prevent it: Handpick slugs off the plants, especially at night. Use slug bait or traps. Encourage natural predators like birds and toads.

Southeast Specific Challenges: The hot, humid summers in the Southeast can create a breeding ground for fungal diseases, so good air circulation and avoiding overhead watering are crucial. Also keep an eye out for Japanese beetles, which can skeletonize the foliage.

French marigolds are excellent companion plants for many vegetables in the Southeast garden. They release compounds into the soil that deter nematodes and other pests.

Good companions include:

• Tomatoes and Peppers: Marigolds help repel nematodes and other pests that can damage these crops.
• Basil: Marigolds deter pests, and basil can also help repel some insects that bother marigolds.
• Cucumbers: Marigolds help protect cucumbers from squash bugs and other pests.

Avoid planting marigolds near green beans, as they can sometimes inhibit their growth.