It's a fact. Growth plates close slower in the absence of testosterone. Testosterone--the hormone that makes them act like stallions--also causes the growth plates in their cannon bones and other long bones to close earlier than they would in a gelding. Once these plates close, they seal, halting further growth. Therefore, colts gelded before puberty (in most cases, before they're yearlings) will grow about 1/2-inch taller than if they were left intact.
I have heard that gelding early produces height and gelding later produces bulk. Stallions exhibit thicker necks, jowls, and wider frames than geldings.
It's a good idea to geld when flies are not hatched yet, and make sure the colt gets adequate exercise after the procedure.
Interesting so let me see if I understand this - if I geld him now (I checked the Farmers Alamanac and March 12,13 and 14th - the sign/sun will be in the feet
) then it will take longer for the growth plates to close and he'll grow taller, but if I wait until he's a yearling (which will be in late April) he'll bulk out...right