I have an apple tree started from seed that was stratified in damp paper towels in my frig. It's been in a 3 gal pot in good rich, compost-enriched soil for 3 months now. I moved it outdoors 2 weeks ago and it's seen sun, breeze, rain, etc. It's gotten more ridged & " woody " since being outside. It's 15" tall now. Should I plant it this fall ( Sept. )-ish ? Or bring in for winter & plant in spring ? First time trying it. Apple guys ??