Marigolds can easily be started from seed indoors in early spring or purchased as seedlings in late spring. With a variety of sizes and colours ranging from shades of yellow, orange, red and white, marigolds are divided into four basic species: African marigolds, French marigolds, the hybrid Triploids and single marigolds. Regardless of species, marigolds love the summer sun and must be planted after the threat of frost has passed.
Starting Seeds Indoors - To get the most bang for your buck, start seeds indoors up to nine weeks before the final frost date for African marigolds and five to six weeks for other species. Follow instructions on your seed packaging for the best results. Always use seeds from a reputable dealer that were packaged for that growing season and a seed-starting potting soil mix made from organic matter such as compost or peat moss and a water-retaining agent such as perlite or vermiculite. Move seedlings outdoors for a few days to acclimate them to the climate before transplanting into beds or containers.
Direct Sowing - Marigold seeds can be sown directly into the soil once the threat of frost has passed and the soil is warm. Follow planting directions as far as spacing, depending on the variety. Marigolds bloom 45 to 60 days after planted, so expect blooms as a late-summer or early fall addition to the garden.
Choosing Seedlings - Because of the popularity of marigold plants, seedlings can be found in just about every nursery and department store garden center. Shop early in the annual season and visit a variety of dealers for the best and most unusual varieties. Full-service garden centers and nurseries will often have a better selection of the newest and more unusual varieties while department store garden centers usually carry the most common types. Choose plants with healthy-looking green foliage and little to no root exposure protruding from the bottom of the packaging. Marigolds are heavy bloomers so the appearance of blooms in the store will have little effect on the performance of your plant in the garden. It will still have months of show left in it.
Planting Seedlings - Seedlings are generally available in four- or six-packs of bedding plants in single and multi-colored varieties. Check with your local cooperative extension office or the USDA hardiness map to find out the expected final frost date for your area to know exactly when to plant. Purchase healthy plants with a plant tag available for planting instructions such as spacing. Marigolds thrive in a nutrient-rich, loose soil in full sun and are at home in both containers and beds. Use marigolds as border plants, as part of a cut garden and as a companion plant in the vegetable garden. While the four-legged-critter-repellant properties of the marigold are simply anecdotal, science proves that marigold roots emit a hormone that repels nematodes and that the heavy scent of the flower can deter cucumber beetles and other pests that rely on smell to find their food. Marigolds are rather self-sufficient once established, needing little to no deadheading and only watering in a long dry spell.