All marigolds are members of the Tagetes genus and are a popular summer growing annual that graces many yards and containers. French marigolds are perhaps the most common variety grown and have the longest blooming period of all the marigold varieties. Flowering from early summer through the first frost, the multi-colored flowers of yellow, orange, mahogany and crimson colors grow up to 12 inches tall. Although aesthetically pleasing to the eye, their scent acts as a natural insect and pest repellent, making them an excellent choice for planting around the perimeter of a vegetable garden.
Grow French marigolds in a location that receives full sun during the morning with partial shade in the afternoon. Plant them in flower gardens as border plants or around the outer edges of a vegetable garden to keep away pests such as rabbits. These hardy annuals last a long time and can endure various weather conditions.
Work the garden soil in spring after the last frost by loosening with a rake or rototiller. Amend the soil by working in organically enriched compost so the soil will drain well.
Dig a hole twice the size as the root ball, being sure to space plants about 10 inches apart. Set the plant into the hole so it sits at the same level it was grown at. Fill in the hole with remaining soil and tamp down gently. Repeat this for all of the plants.
Water your newly planted marigolds well so the soil is moist, but with no standing water. French marigolds need frequent watering to keep the soil moist, and using a soaker hose works best for this. Water every few days or when the top 1 inch of soil is dry. In warmer weather, water more often as needed.
Fertilize your newly planted French marigolds with a slow-release liquid fertilizer (e.g., 5-5-5). Apply another application in mid-summer when marigolds may take a break from producing as many new blooms; this application will help them produce again abundantly through the fall.
Deadhead spent flowers on a regular basis to prolong the growing season and encourage more blooms. Keep tall plants pinched back to produce a bushy, full-looking plant.