I've gone for entire decades without fertilizing any of my plants. It's not necessary for them to stay alive, and when plants do grow at their maximum pace, it's a constant job to keep trimming them. Something I enjoy, most of the time, but many would not. A more sedate pace of growth is usually more appreciated for a houseplant. But regardless of the pace of growth, even slow-growing plants can reach a point where their appearance is no longer appealing to their owner, as you have discovered with your arrowhead vine. Newly-planted vine cuttings, like your pot of arrowhead, rarely retain an upright, bush appearance for long. Hoping it will is like hoping a baby won't grow up. It's just not possible for it to stay a juvenile indefinitely. But unlike people, most plants can be manipulated to retain that appearance by trimming and propagating. Possible for arrowhead vine, but not birdnest fern.
The links I posted have many pics of each plant, which will give you an idea of what they *could* do in an ideal environment, and what is generally a normal appearance. Most/many pics have (optional) captions, which can help explain why each photograph was shared, and/or what the photographer is trying to show.
There are also other database entries in the database on this site for various cultivars of each species that can offer more pics.
