French Marigold in Zone 9B — Desert Southwest

French Marigolds are a fantastic addition to any Desert Southwest garden. Their bright blooms bring cheerful color, plus they attract beneficial insects and even deter some pests from your tomatoes and peppers. You can even use the petals in salads for a slightly citrusy flavor.

While our extreme heat and intense sun can be challenging, French Marigolds are surprisingly resilient. With proper timing and a little attention, you can enjoy their beauty throughout our long, 313-day growing season.

Starting French Marigold seeds indoors is an option, but it's honestly not essential in our climate. It's mainly useful if you want a very early start, giving you blooms before the worst of the summer heat arrives. If that's your goal, sow seeds indoors from early to late January, about six weeks before you plan to transplant.

Use seed trays with a good seed-starting mix and keep them consistently moist – bottom watering helps prevent damping off. Provide warmth and plenty of light, either from a sunny window or a grow light. Our very-early spring means you'll need to be ready to transplant sooner than gardeners in other regions.

Transplant your French Marigold seedlings outdoors from mid February through early April, after the danger of frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense Desert Southwest sun and wind.

Plant them 8-10 inches apart in well-draining soil. Even though it's still early spring, keep an eye on the forecast and be ready to protect young transplants from any unexpected temperature dips.

Direct sowing French Marigold seeds is a simple and reliable method for our climate. You can direct sow from early February through mid October, giving you plenty of flexibility. The soil needs to be warm enough for germination, so waiting until after the last expected frost is ideal.

Prepare the soil by loosening it and removing any rocks or debris. Sow seeds 8-10 inches apart and cover them lightly with soil. Keep the soil consistently moist until the seedlings emerge. Direct sowing is especially convenient for succession planting to ensure a continuous supply of blooms.

French Marigolds are drought-tolerant once established, which is a huge plus in our arid Desert Southwest environment. However, they do need consistent watering, especially during the hottest months. Aim to provide about 1 inch of water per week, either through rainfall or irrigation.

During the spring and fall, you can usually water deeply once a week. In the extreme summer heat, you might need to water every other day, or even daily if they're in containers. Use the "finger test" – if the top 2 inches of soil are dry, it's time to water. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases, even in our low humidity.

Signs of underwatering include wilting leaves and dry, crumbly soil. Overwatering can lead to root rot, indicated by yellowing leaves and soggy soil. Applying a layer of organic mulch around your plants helps conserve moisture and regulate soil temperature, which is especially beneficial during our extreme summers.

Deadheading is key to 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.

You can deadhead anytime during the growing season, whenever you see faded or dried-up flowers. As the first frost approaches around mid- December, you can let the last flowers go to seed if you want to collect them for next year's planting. Otherwise, continue deadheading until the plants naturally decline.

You can expect your first harvest of French Marigold blooms about 50 days after planting, which means late March through mid December depending on your planting time. 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. French Marigolds are continuous bloomers, so you can harvest them regularly throughout the growing season. As the first frost approaches in mid- December, you can either let the last flowers go to seed or harvest them for one final burst of color.

Here are three common problems you might encounter with French Marigolds in the Desert Southwest:

Spider Mites in Dry Heat

• What it looks like: Fine webbing on the leaves and stems, tiny yellow or brown spots on the leaves, and overall plant weakness.
• What causes it: Spider mites thrive in hot, dry conditions, which we have in abundance. They suck the sap from the leaves, causing damage.
• How to fix/prevent it: Increase humidity around the plants by misting them regularly (early in the day so foliage dries quickly) or using a humidity tray. 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 buds. Leaves curl, yellow, and die.
• What causes it: Powdery mildew is caused by fungi that thrive in warm days, cool nights, and moderate humidity. Dry leaf surfaces actually favor it.
• How to fix/prevent it: Improve air circulation by spacing 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.

Slugs on Young Plants

• What it looks like: Holes in the leaves of young plants, slimy trails on the soil surface.
• What causes it: Slugs are attracted to moist environments and can damage young, tender plants.
• How to fix/prevent it: Handpick slugs at night. Create barriers around plants using copper tape or diatomaceous earth. Reduce hiding places by removing debris from around the plants.

Desert Southwest Specific Challenges: Our extreme heat and arid humidity can stress French Marigolds, making them more susceptible to spider mites. Monsoon rainfall can also create conditions favorable for powdery mildew. Proper watering, good air circulation, and vigilant monitoring are essential for success.

French Marigolds make excellent companions for many vegetables in the Desert Southwest garden. They deter pests and attract beneficial insects:

• Tomato, Pepper, Basil: Marigolds release compounds into the soil that deter nematodes and other soil pests that can harm tomatoes and peppers. Basil also helps repel pests.
• Cucumber: Marigolds attract pollinators, which are essential for cucumber production.
• Beans-green: Marigolds deter bean beetles.

Avoid planting French Marigolds near beans-green. While they deter some pests, they can also attract spider mites, which can then infest your bean plants.