French Marigold in Zone 7B — Desert Southwest

French Marigolds are a fantastic addition to any Desert Southwest garden. Their bright, cheerful blooms add a pop of color, plus they help deter pests from your tomatoes, peppers, and other veggies. They’re also surprisingly drought-tolerant, which is a huge win in our arid climate.

Desert gardening definitely has its challenges, like extreme heat and alkaline soil. But with smart timing and a few tricks, you can absolutely grow beautiful French Marigolds. Our long 245-day growing season gives you plenty of opportunity to enjoy these beauties in your garden.

Starting French Marigolds indoors gives you a head start, especially if you want blooms as early as possible. Start your seeds indoors from early February through early March, about six weeks before you plan to transplant them outside. Use seed trays with a good seed-starting mix, and keep them warm and under grow lights.

Bottom watering is key to prevent damping off. Just set the tray in a shallow dish of water and let the soil soak it up from the bottom. Given our very-early spring character in the Desert Southwest, indoor starting is a good strategy to get a jump on the season.

Transplant your French Marigold seedlings outdoors from late March through early May, after the risk of frost has passed. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense desert sun.

Space them about 8-10 inches apart to allow for good air circulation. Keep an eye on the weather forecast. Even though it's late spring, a sudden cold snap can still happen.

Direct sowing French Marigolds is a simple and effective method, especially for later blooms. Sow seeds directly into well-prepared soil from mid March through mid September. Make sure the soil temperature is consistently warm, around 70°F.

Prepare the soil by loosening it and adding some compost. Sow seeds about ¼ inch deep and space them 8-10 inches apart. Keep the soil consistently moist until the seedlings emerge. Direct sowing is great for extending your bloom season into the fall.

French Marigolds are surprisingly drought-tolerant once they're established, which makes them perfect for our Desert Southwest climate. During the active growing season, especially during our extreme summer heat, water deeply about once a week. Adjust based on rainfall – take advantage of our monsoon moisture!

Use the "finger test" to check the soil moisture. Stick your finger about 2 inches deep into the soil near the base of the plant. If it feels dry, it's time to water. Aim for about an inch of water per week. Water at the base of the plant to avoid wetting the foliage. Our arid humidity means powdery mildew is less of a concern, but it's still best to avoid overhead watering to minimize any potential issues.

Signs of underwatering include wilting leaves and dry, brittle stems. Overwatering can lead to root rot, indicated by yellowing leaves and a mushy stem base. A layer of mulch around the base of the plants helps retain moisture and regulate soil temperature, which is especially important in our desert environment.

Deadheading is crucial for keeping your French Marigolds blooming throughout the 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.

Continue deadheading throughout the growing season, from spring through fall. As the first frost approaches around mid- November, you can let the last few flowers go to seed if you want to collect them for next year.

You can expect your first French Marigold blooms about 50 days after planting. That means if you started seeds in early spring, you could be harvesting flowers by early May and continue through mid November. Harvest the flowers when they are fully open and the color is vibrant.

To harvest, simply snip the stem just below the flower head. This encourages the plant to produce more blooms. To save seeds, allow some of the flower heads to dry completely on the plant. Once dry, collect the seeds from the dried flower heads for planting next season. As the first frost approaches in mid- November, harvest any remaining blooms to enjoy indoors.

Here are some common problems you might encounter with French Marigolds in our Desert Southwest gardens:

Spider Mites

• What it looks like: Fine webbing on the plant, tiny moving dots (the mites themselves), and leaves that look stippled or speckled.
• What causes it: Hot, dry conditions, which are typical for us. Spider mites thrive in low humidity.
• How to fix/prevent it: Increase humidity around the plants by misting them regularly (especially in the mornings). A strong blast of water from the hose can dislodge them. Insecticidal soap or neem oil can also be effective.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves, stems. Leaves may curl, yellow, and die.
• What causes it: Various fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it (unlike most fungi).
• 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.

Slugs

• What it looks like: Holes in leaves, especially on young plants. Slimy trails on the soil or foliage.
• What causes it: Damp conditions, often after monsoon rainfall. Slugs are more active at night.
• How to fix/prevent it: Handpick slugs at night. Use beer traps (shallow dishes filled with beer) to attract and drown them. Diatomaceous earth around the base of the plants can also deter them.

Desert Southwest Specific Challenges: The extreme heat and intense sunlight can stress French Marigolds. Providing some afternoon shade during the hottest part of the day can help. Our alkaline soil can also affect nutrient uptake, so amending the soil with compost is essential. The monsoon season can bring humidity spikes that, while brief, might increase the risk of fungal issues.

French Marigolds make excellent companions for several plants in the Desert Southwest garden. Plant them near tomatoes and peppers to deter nematodes and other pests. The marigolds release compounds into the soil that repel these unwanted visitors. Basil also benefits from being planted near marigolds, as the marigolds deter pests that might attack the basil.

Cucumbers also enjoy the company of French Marigolds, as the marigolds help to repel cucumber beetles. Avoid planting French Marigolds near beans. While marigolds deter some pests, they can attract others that will feed on bean plants.