I backed Mare in a western saddle because that’s what I happened to have. She’s living the 24/7 turn out and hand walking life until we move. I will be buying an English saddle for her but am lacking clarity on what to pursue since she is going to be growing for the next several years. Treeless? Adjustable tree?
The type of saddle doesn’t matter here. If you prefer to ride in a CC saddle, buy a CC saddle.
How old is she? If she’s 3, then you’re in for a few changes at least. If she’s 5, maybe 1 change.
What can help you get through with the fewest changes is to buy into the idea that you can properly fit a saddle about 2 sizes too big as long as it fits the angles and everything, and then use proper padding to fill in. www.balanceinternational.com does this very well, but any competent saddle fitter can do it too.
Pads are loads cheaper than buying a new saddle very 1-2 years. You can use shims and thicker and thinner pads as she not only widens, but changes shape a little. You would still need some education on doing that, and Balance does that well IME and IMO
Treeless still needs appropriate padding, not all treeless are created equal. You’d absolutely want one with a proper channel - has a channel at all, and it’s wide enough. They do require the rider to be more balanced since there’s no rigid tree to help deal with more than minor lateral imbalances
Adjustables are fine for a few increases, but at some point you change the overall shape, no matter if it’s technically wide enough up front.
She’ll be within a month or two of her 4th birthday by the time she’s back in a program. I absolutely cannot afford a new saddle every year or two until she finishes maturing! Thank you for the resources.
I’d invest in an independent saddle fitter who has access to used saddles (and good quality used ones hold value really well), and also go to the Balance site to see what you need for videos, measurements, etc. Buy used for sure!