A mate of mine has been told that when planting marigolds to cut off the head of the centre flower this will make the plant produce more flowers anybody heard of this and does it work?
If you take the top bit of shoot as well you will encourage side shoots to flower, it would be better to take the tip out before the flower really develops though.
It's not necessary keith on most marigolds. Small french marigolds are self branching but some of the taller african or american marigolds may benifit from stopping early on. Personally, i wouldn't bother whatever marigold i grew.