French Marigold in Zone 7B — Northern California

French Marigolds are a fantastic addition to any Northern California garden. Their vibrant colors brighten up the garden, and their edible petals add a unique zest to salads and other dishes. Plus, they attract beneficial insects that help keep your other plants healthy.

While we NorCal gardeners contend with dry summers and occasional water restrictions, the French Marigold's drought tolerance makes it a perfect fit. With our long 245-day growing season, you'll have plenty of time to enjoy these cheerful flowers.

Starting French Marigold seeds indoors gives you a head start, but it's not always necessary in our mild climate. If you want blooms extra early, or live in a microclimate that gets a little cooler, starting indoors is a good idea.

Sow seeds indoors from early February through early March, about six weeks before you plan to transplant them. Use seed trays with good drainage, provide warmth (a heat mat helps), and ensure they get plenty of light, either from a sunny window or a grow light. Bottom watering is a great way to keep the soil moist without damping off. Given our early springs, starting indoors gives you an edge.

Transplant your French Marigold seedlings outdoors from late March through early May, once the danger of frost has passed. Be sure to harden them off for about a week before transplanting. Gradually expose them to outdoor conditions, starting with a few hours a day, to acclimate them to the sun and wind.

When transplanting, space them about 8-10 inches apart to allow for good air circulation. Even though we have a long growing season, be mindful of any late cold snaps that can still occur during this time.

Direct sowing French Marigold seeds is a simple and effective method, especially in our forgiving climate. You can direct sow from mid March through mid September, giving you a wide window of opportunity.

Prepare the soil by loosening it and removing any weeds. Sow seeds about ¼ inch deep and keep the soil consistently moist until they germinate. Space the seeds about 8-10 inches apart. Direct sowing is convenient, but you might get blooms a little later than if you start indoors.

French Marigolds are relatively drought-tolerant once established, which is a huge benefit in our Northern California gardens, given our dry summers and occasional water restrictions. Water deeply but infrequently.

During the spring, when temperatures are milder, water about once a week, or when the top two inches of soil feel dry to the touch – do the "finger test." In the heat of summer, you might need to water twice a week, providing about 1 inch of water each time. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our sometimes foggy microclimates.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to root rot, so watch out for yellowing leaves. A layer of mulch around the base of the plants can help retain moisture and suppress weeds, reducing the need for frequent watering.

Pruning French Marigolds is mainly about deadheading – removing spent flowers. This encourages the plant to produce more blooms throughout the season.

Simply pinch or cut off the faded flowers just below the flower head, down to the next set of leaves. Do this regularly, from spring through fall, to keep your plants looking tidy and producing flowers. As the first frost approaches around mid- November, you can let the last flowers go to seed if you want to collect them for next year.

You can expect your first harvest of French Marigold flowers about 50 days after planting, typically from early May through mid November in our area. Harvest the flowers when they are fully open and at their peak color.

To harvest, simply cut the stem just below the flower head. Regular harvesting encourages the plant to produce more flowers. As the first frost approaches in mid- November, harvest any remaining flowers. You can also let some of the flowers dry on the plant to collect the seeds for next year's garden.

Here are a few common problems to watch out for with French Marigolds in Northern California:

Spider Mites

• What it looks like: Fine webbing on the leaves and tiny, moving specks (the mites themselves). Leaves may look stippled or yellowed.
• What causes it: Hot, dry conditions, which we often experience during our NorCal summers.
• How to fix/prevent it: Increase humidity around the plants by misting them with water. A strong blast of water from the hose can dislodge the mites. Insecticidal soap or neem oil can also be effective.

Powdery Mildew

• What it looks like: White or grayish powdery coating on leaves and stems. Leaves may curl, yellow, and die.
• What causes it: Warm days, cool nights, and moderate humidity, which can occur in our coastal microclimates or during temperature swings. 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 surprisingly effective.

Slugs

• What it looks like: Holes in leaves, especially on young plants. Slimy trails on and around the plants.
• What causes it: Moist conditions, especially after rain or watering.
• How to fix/prevent it: Handpick slugs off plants, especially at night. Use slug bait or traps. Diatomaceous earth around the base of the plants can also deter them.

Northern California Specific Challenges: Our moderate-to-hot, dry summers can stress French Marigolds, making them more susceptible to spider mites and powdery mildew if not properly watered and spaced. Monitor your plants regularly and adjust your care as needed to keep them healthy and blooming.

French Marigolds make excellent companions for many plants in your Northern California garden. They release compounds into the soil that deter nematodes and other pests.

Good companions include tomatoes, peppers, and basil, as the marigolds help to repel pests that often bother these plants. They also work well with cucumbers, attracting pollinators and deterring cucumber beetles. Avoid planting them near green beans, as they can inhibit their growth.