For most home gardeners, marigolds do best planted about 8–12 inches apart, depending on the variety.

Quick Scoop

  • Compact or French marigolds: space plants 8–10 inches apart.
  • Signet marigolds: can be a bit closer, around 6–8 inches apart.
  • Tall/African (American) marigolds: give them 10–18 inches between plants so the big plants and blooms have room.
  • When in doubt: check the plant tag or seed packet and space based on the mature width listed.

Why spacing matters

  • Better air flow reduces fungal diseases and rot in thick, leafy marigold foliage.
  • Enough elbow room lets roots spread, so plants flower more instead of stretching weakly for light.
  • Crowded marigolds can look leggy and sparse on top, while well‑spaced plants fill in into a solid, colorful hedge after a few weeks.

Think of a bed of short French marigolds: if you set them about 9 inches apart in a zig‑zag pattern, they grow together into a bright, low “ribbon” of color without smothering each other.

Simple planting steps

  1. Check your variety (French, signet, African/tall) and note the expected height and spread on the tag or packet.
  1. Mark spots in the soil at the final spacing (for example, every 8–10 inches for French marigolds).
  1. Plant seedlings at each mark, water in well, and keep soil moist until they take off.

If you’re sowing seeds directly, you can scatter or line‑sow them about 1 inch apart, then thin the seedlings later so the strongest plants stand at the proper final spacing.

Container & border tweaks

  • In pots and window boxes you can tuck them slightly closer, since you control water and feeding, but avoid packing them so tight that foliage touches immediately.
  • In a 12‑inch round pot, 3 compact French marigolds usually make a full, lush display without crowding.
  • Along a vegetable bed edge, use your chosen spacing (for example 10–12 inches for taller types) and stagger plants in a loose zig‑zag for a more natural look than a single straight line.

Mini FAQ

  • “Is 6 inches apart OK?”
    • Only for very small or signet types; most common marigolds are happier at 8 inches or more.
  • “What if I already planted them too close?”
    • You can gently dig up and move every second plant to a new spot, aiming for those 8–18 inch gaps based on type.

TL;DR:
Plant smaller French or signet marigolds around 6–10 inches apart and bigger African types 10–18 inches apart, always matching spacing to the plant’s mature size for the best bloom show.

Information gathered from public forums or data available on the internet and portrayed here.