What can I do about my ivy that's getting too big for its post?

Indoor or outdoor plant?

Unfortunately cutting it back may the best answer if it's an outside plant on a permanent structure. Keep the ends of the vines (the uppermost part with the smallest leaves) trimmed and the bases will grow in thicker and start to fill out.

If it's a houseplant or outside on a non permanent structure you can always remove the post and add a taller one or a trellis. Vines will take a fair amount of abuse and still thrive. Place the vines on the new post and tie loosely with zip ties, twist ties or twine until they've reattached then remove the ties. It might be time to repot it if it's a houseplant as well.

FYI: English ivy is considered an invasive species outdoors and a nuisance plant. It will take over an area quickly and can tear down walls and fences!

Repot it into a bigger pot. If it gets too rootbound, it will eventually die.

I agree with both of the previous answers. You can also cut an end off, root it in dechlorinated water and make yourself another ivy stake.

Yes, I believe I will

Thank you!