My 2 year old is only 14.1hh but should(according to her pedigree) mature to at least 15hh…is this a sign that she may runn best next year…or is she just going to be a little late this year or should I not even run her until later??
Height is based on maturity, so yes, she is probably immature. This doesn’t mean she can’t race well this year (after all, an immature future-stakes winner would still be a nice horse!), but it does mean she will likely perform better later.
It’s up to you whether you want to wait until you’re “sure” she’s mature before racing her, or if you’d like to give her experience/test her out in the meantime.
Thanks, that really helps…I have already started her training so I will keep watch, maybe try a race and go from there. 
ok, so wait, say I own a 2 year old( just SAY haha) and say this little guy is well, little, will he get any taller as he gets more mature or will he always be little??
They can grow after the age of 2. I just checked on one of my 3 yos last night; in December he was 14hh, as of now he’s 14.3hh. 
He’s been having energy issues…he must be tired from that growth spurt, LOL.
1 of mine had a big spurt she was 14.2hh last season as a 2yo and start of this year as a 3yo she is 16.2hh
that is encouraging for my little guy 
!! thanks for your help and I can’t wait to see him grow up 
Wow. This is a useful thread.
I suspect height and maturity depend on just how tall the horses’ final height is going to be. I purchased Opal Rock from last years 2yo auction. She’s created so there was nothing to go on as regards her final height. Born January 28th she was just 14.0hh, I thought she must have been very immature but today at age 3 she is still only 14.3hh ( very small for a TB) so she is clearly just a tiny mare and should be fully mature now.
My only worry with this is does her height automatically put her at a disadvantage when running, or does the race code ignore height? It may make a difference to her stride length and I know that is important. I have turned down a couple of stallions this year that I would have liked to use because the potential height of the foal was something like 14.2 - 15.2 and I was afraid I would breed a disadvantaged foal. Is this likely?
Race code tries to balance things out…smaller horses have shorter stride length, but higher stride rate (i.e. they move their legs faster 
). Extra-large horses (17h+) are also slightly more likely to be slightly less sound. (Though the reverse is not true…a 14.3h horse is not likely to be more sound than a 15.3h horse, ceteris paribus.) Small horses are also more likely to mature earlier than big ones (if I’m remembering correctly).
And yes, height/maturity are based on how big the baby will be eventually…all babies are born at 52-63% of their full adult height, and grow according to how mature they are. Once they hit their peak, they are full-grown.