Philodendron is fortunately quite easy to propagate. Each node can root, so a plant of this size can be cut into multiple sections to grow into new, fresh plants. (If it's too many for you to keep, perhaps they can become family giveaways to perpetuate the heirloom.) A node is the point along the stem where roots and leaves emerge; it looks like a joint between smooth sections of stem, and primordial (potential) buds for adventitious roots are visible as small dark nubs. For propagation, you don't have to cut it into pieces as small as one node per section, but you definitely could. How far along the stem you wish to leave each section is up to you, though since growth may only start at one or two nodes per piece, keeping them on the small side may give the future plant a tidier appearance. We do not know how likely it is that the oldest part of the stem will propagate successfully, but it's probably amenable to rooting.

You can get nodes to root in either a container of plain water or in moist potting soil. We don't have research demonstrating one medium is definitively better than the other overall, though rooting in water may be faster at the beginning, with the trade-off being an adjustment period the plant will experience as it transitions to growing in soil later on.

Given the large size of this Philodendron, you can certainly experiment with different techniques; it is likely the success rate overall will be high. For all propagules (the cuttings and the resulting "baby" plants), keep the humidity around them high by either giving them a clear tent/bag enclosure of sorts or consider using a room humidifier. In addition to being a growing condition that Philodendrons prefer overall, high humidity will slow the loss of moisture from the tissues while the plant develops new roots.

If you wish to see examples of what to look for in taking cuttings and how they're start growing, videos and tutorial blogs abound online by home gardeners on propagating cuttings in this manner (especially Philodendrons as they are enjoying renewed popularity among young gardeners). When making the cuts, ideally you want to cut not far (perhaps half an inch) from the node you're intending to root so the excess stem doesn't contribute to rot as it naturally dies back to the node that's growing. We do not know exactly how long it will take to generate new plants, but when we reach spring's longer days and brighter light, it's not unreasonable to expect accelerating growth.

Opinions on Philodendron potting mix vary, but they are fairly forgiving if not over-watered nor allowed to get too dry. Typical houseplant potting soil (sometimes labeled potting "mix") is adequate, though probably should be amended with additional perlite for improved drainage. Some growers of Philodendron and their kin use a more specialized blend of several other ingredients that have less "soil" and slightly chunkier faster-draining materials, but those can be more expensive to obtain. In either case, they key is to have good drainage, use a pot that allows for good drainage (so, with one or ideally several drainage holes in the bottom), and don't keep the potting mix soggy nor let it get very dry between waterings.

If this parent plant hasn't been repotted recently, it too would appreciate a fresh mix, either when you pot-up your new cuttings or later this spring. When you remove it from this pot, remove what old soil you can without damaging too many roots and replace it with fresh. Old potting soil/mix can accumulate salts (not necessarily sodium, but other minerals too) from tap water and fertilizer that, over time, can reach levels which damage roots. It also can compress as it slowly breaks down over time, which doesn't allow it to "breathe" as well and holds water for longer and longer periods. Good root growth fuels good shoot (stem, leaf) growth, so keeping the roots vigorous and healthy is key to helping the top growth look its best.

If you want to minimize it's bare-bottomed lanky look going forward, you can try training some of your new cuttings up a support. Philodendrons of this type are climbers in nature, adhering their stems via specialized roots to the trunks of trees. In the home, we often use stakes to support most tall shrubby or vining plants, but in this case, they can and will attach to a "moss pole," which is essentially when a stake is augmented with a material to give it more girth and provide the roots a place to anchor. Here too, tips and materials vary and abound online, but often they are sturdy slender plant stakes that are wrapped in long-fiber sphagnum moss or something else that can be moistened on occasion and can accommodate more than a year's growth. Climbers grown in this manner tend to grow larger leaves and retain their lower, older leaves for longer; they also can grow leaves closer together so they won't end up stretching-out as dramatically. You can always try one plant to see how you like the look and transition rest later if it's successful. Because the new shoot at the base of the plant now is so low to the ground, this would be an ideal growth on which to try this technique.

Miri