Hi Tui, is it helpful to pinch out the first flower heads to promote a fuller flowering marigold plant?
It is standard practice to pinch the tips of bedding plants (flowers) when planting to encourage them to bush out and grow more flowers, as long as you don’t want instant colour in the garden and can wait for the flowers. It helps the plant establish better flowers if they're are removed as the plants energies are going into producing flowers and not establishing roots, so you will get prolonged flowering if you do this. Remember to dead head and remove spent flowers, this will prolong flowering as well.
Thanks, Tui Team.