We are growing apios americana for the first time and the leaves are turning yellow. We started last spring with four rhizome “beads”; we placed each bead in its own 3-gallon plastic pot and sank the pots in the ground. The plants seemed to grow well. Over the winter, we left them outside without any special preparation. This year, vines started nicely and grew up a trellis but now the leaves are yellowing and it seems like growth has slowed down. I’m wondering if the 3-gallon pots are too small and the rhizomes are root-bound. If so, any suggestions for what to do? We can try to excavate the pots without disrupting the vines but it seems like it’ll be tricky.
Also, in case it’s useful, we live in Pennsylvania in the Delaware River valley.
Thanks for any suggestions!