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How to Grow Giant Yellow Marigolds From Seeds

The African marigold (Tagetes erecta) has the largest flowers of all the marigold varieties. The flowers are commonly 3 to 4 inches in diameter; when compared to the 2-inch flowers of French marigolds and some hybrids, the African marigold is a giant variety. Other common names include Aztec marigold and big marigold, according to the Missouri Botanical Gardens. Though the name suggests a different origin, African marigolds are native to Mexico. Grow these large annuals from seed each year to infuse your garden with giant yellow flowers.

Things You'll Need

  • Seed-tray, 2-inch pots or 2-inch cell packs
  • Peat
  • Perlite
  • Vermiculite
  • Trowel
  • Shovel
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Instructions

    • 1

      Purchase seeds in early spring. Some yellow African marigold varieties to try are Antigua primrose, Marvel yellow, Antigua yellow and Inca yellow.

    • 2

      Start giant yellow marigold seeds indoors two to three weeks before winter frosts leave your area. Use a seed tray, 2-inch seed-starting cells or individual 2-inch pots. Plastic, biodegradable peat or cardboard or ceramic are all suitable pot materials to use.

    • 3

      Make your own potting mix using equal parts peat moss, vermiculite and perlite or purchase a ready-mixed seed-starting formula at a local garden center. Put the seed-starting mix into a bucket and mix it with water until it is damp and crumbly.

    • 4

      Place the seeds 1 inch apart in the seed flat or one seed per cell or pot when using 2-inch containers. Cover the giant yellow marigold seeds with 1/4 inch of soil.

    • 5

      Keep the pots containing the giant yellow marigold seeds at 70 to 75 degrees Fahrenheit. The marigold seeds will germinate in three to five days.

    • 6

      Grow the giant yellow marigolds indoors until they are 2 to 3 inches tall and until the ground thaws and the last frosts are gone.

    • 7

      Transplant the marigold seedlings outdoors into a sunny area where the ground drains well. Dig holes 2 inches wide and the same depth as the seedling's root ball. Slide the marigold seedlings out of the containers. Space the marigold seedlings 12 to 18 inches apart.

    • 8

      Water marigolds once a week during mild weather and twice a week during hot, dry weather. As long as the soil is still damp 1 inch below the surface, the roots are getting enough water.