French Marigold in Zone 7A — Pacific Northwest

French marigolds are a fantastic addition to any Pacific Northwest garden. Their bright, cheerful blooms bring a pop of color, and they're incredibly versatile – use them in borders, containers, or even as edible garnishes. Plus, the cool nights we experience here seem to intensify their fragrance.

Even though we have mild summers, you might be concerned about getting warm-season bloomers going. Luckily, French marigolds are quick to mature, fitting nicely into our 183-day growing season. With the right timing, you'll have plenty of time to enjoy their beauty.

Starting French marigolds indoors gives you a head start, especially with our slow-warming springs. If you're eager for early blooms, sow seeds indoors from mid-March through early April, about six weeks before you plan to transplant.

Use seed trays with a good seed-starting mix. Keep them consistently moist by bottom watering – set the tray in a shallow dish of water until the surface of the soil glistens. Provide warmth and plenty of light, either from a sunny window or a grow light, to combat those overcast spring days.

Transplant your French marigold seedlings outdoors from early May through mid-June, once the danger of frost has passed. Before planting them in the ground, harden them off by gradually exposing them to outdoor conditions for about a week.

Space the plants 8-10 inches apart in a sunny spot. Keep an eye on the weather forecast, as a late cold snap can still happen. If a chilly night is predicted, cover your young plants with horticultural fleece or cloches.

Direct sowing is a simple and effective way to grow French marigolds, especially if you're not in a rush for early blooms. Sow seeds directly into the garden from mid-April through mid-August.

Make sure the soil is warm and workable, and prepare the planting area by loosening the soil and removing any weeds. Plant seeds about ¼ inch deep and space them 8-10 inches apart. Keep the soil consistently moist until the seedlings emerge.

French marigolds are quite drought-tolerant once established, which is a blessing during our dry summer months. In the spring, when the plants are young, water them regularly to help them develop strong root systems.

During the dry summer months, check the soil moisture by sticking your finger about 2 inches deep. If the soil feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid wetting the foliage, which can encourage powdery mildew in our humid springs.

Signs of underwatering include wilting leaves and stunted growth. Overwatering, on the other hand, can lead to root rot, so make sure the soil is well-draining. A light layer of mulch around the base of the plants can help retain moisture and suppress weeds, but avoid piling it up against the stems.

Deadheading is key to keeping your French marigolds blooming all season long. Throughout the 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. As the first frost approaches in mid-October, you can let the last flowers fade and dry on the plant if you want to collect seeds for next year's garden.

You can expect your first French marigold blooms about 50 days after planting, usually from early June through mid-October. Harvest the flowers when they are fully open and brightly colored.

To harvest, simply snip the stem just below the flower head. Regular harvesting encourages the plant to produce even more flowers. If you want to save seeds, allow some of the flower heads to dry completely on the plant. Once they are dry and brown, you can collect the seeds for next year's planting.

As the first frost approaches in mid-October, harvest any remaining blooms to enjoy indoors. The flowers can also be dried for use in potpourris or other crafts.

Here are a few potential problems to watch out for with French marigolds in the Pacific Northwest:

Spider Mites

• What it looks like: Fine webbing on the plant, tiny yellow or brown spots on the leaves, and overall decline in plant vigor.
• What causes it: Spider mites thrive in hot, dry conditions, which can occur during our summers, especially in containers.
• How to fix/prevent it: Increase humidity around the plants by misting them regularly. You can also spray with insecticidal soap or neem oil. Make sure to get good coverage on the undersides of the leaves, where spider mites like to hide.

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 spring weather can be perfect for it.
• 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. Slimy trails on and around the plants.
• What causes it: Slugs love our wet springs and mild temperatures.
• How to fix/prevent it: There are many ways to combat slugs, including handpicking them, using slug bait, or creating barriers with copper tape or diatomaceous earth. You can also encourage natural predators like birds and beneficial nematodes.

Pacific Northwest Specific Challenges: Our dry summer months can sometimes lead to spider mite infestations, so be sure to monitor your plants and take action if you see any signs of them. The cool, wet springs can also increase the risk of powdery mildew, so provide good air circulation and avoid overhead watering.

French marigolds are excellent companion plants for several vegetables in the Pacific Northwest garden. Plant them near tomatoes, peppers, and basil, as their scent repels many common pests that bother those crops. They also work well with cucumbers, helping to deter cucumber beetles.

Avoid planting French marigolds near beans. While marigolds are generally beneficial, they can inhibit the growth of bean plants, so it's best to keep them separated.