Boots, like gloves are long
Unless you're riding for show, or in full dress, it doesn't matter as much what kind of boots you wear. As long as the boots have a good heel on them so that your foot doesn't slip through, either paddock boots or tall boots can be worn. (Or any other pair of boots.)
Boots Mallory is 5' 7".
Children should wear tall boots when they are 12 years of age.
Boots Southerland is 6' 2 1/2".
Long boots, more often called Tall boots are designed to 'stabilize' a riders leg and to look stylish. Short boots typically worn with half chaps when jumping are designed to provide support and be easier to take on and off. Neither one is really any safer than the other. That being said, if the rider had and accident and they needed their boots removed short boots and half chaps would be easiest to remove. Tall boots have a zipper up the side or back for the most part nowadays, but they still might need to be cut off if they can't be pulled off easily in an emergency.
Hopalong cassidy boots
There is no 'magic' age to move into tall boots. But it is always smart to wait for the child to have most of their growth already finished. Boots are very expensive so you want to get the most wear out of them. When children are growing fast they can outgrow a pair of boots every six months or so. By the time a rider hits the age of 12 or 13 years old they may be ready for tall boots. It may also help the budget if there is a consignment shop where you may be able to get a good pair of pre-owned boots. Another option is tall rubber boots. They are much less expensive as the leather boots.
The tall riding boots of today are the ancestors of boots worn by 17th century British soldiers. On the battlefield these tall boots protected the lower legs and gave the soldiers better contact with the horse's side.
Classic tall is a style of boot that features a top that goes up to the calf area of the leg. UGG Boots is a brand that features many different styles of classic tall boots.
You can purchase UGG's classic tall boots at the Amazon website. Once on the page, type "UGG classic tall boots" into the search field at the top of the page and press enter to bring up the items.
as long as they are strong boots
just below the knee