Rooting your jade leaf in water is possible, it just takes some more effort as it's difficult for the leaf to keep an upright position. It's easier to use a small juice glass for this method, and using mesh or toothpicks can help keep the leaf vertical.
The trick to successfully propagate a Jade plant in water is to change the water once or twice a week, once it turns grubby. Adequate roots emerge in 4-5 weeks, which eventually reduces the risk of root rot. You can then keep your plant at the desired location where it gets bright and indirect light all day.
Jade plants are really easy to propagate via stem or leaf cuttings. In fact, in the wild, leaves that break off and land on the ground will root themselves in a few weeks without any human intervention. Take a hint from nature. Keep it simple and stay as hands off as possible.
If there's not much humidity in the air, lightly mist the cuttings with water daily. New growth on each cutting is a good sign that roots are forming. Most cuttings take about 3 weeks to show signs of rooting, followed by established root formation in 4-6 weeks.
take a leaf and cut it into sections, each section with a vein. The bottom portion of the vein can then be pressed into the propagation medium with the leaf portion sticking up to root just like a leaf cutting. In this manner one leaf can produce up to a dozen new plants.
The lack of a good root structure indicates to me that your Jade Plant (Crassula argentea), was probably being over watered in its previous pot. Succulents generally will send their roots out only far enough to find a sufficient source of water.
Jade plants can be propagated from stem or leaf cuttings. Keep in mind that it takes it takes a while to get a nice sized jade plant from leaf cuttings.
Jade plants lose some lower leaves naturally as part of the aging process. Those do not grow back. Some leaves lost for other reasons will grow back, slowly, if you correct the conditions that caused them to drop off.
You can root your jade plant stem cutting directly in soil. Succulents are very resilient, so this almost always works. The only downside is that you can't really keep an eye on your cutting's progress, at least not until new leaf growth starts to appear.
Check the soil around the roots to be sure. Your jade plant will need a generous soak about every 14 days, although the frequency in which you have to water your plant will depend on the season. Jade plants need more water in the summer and much less in the winter.
During its dormant period in winter, from November to February, the money tree requires even less water. Make sure that the root ball does not completely dry out but water only sporadically during this time. Rainwater is ideal for watering the money plant.
How to Water Jade Plants. Jade plants are succulents (they hold water in their leaves), so they don't do well when sitting in constantly moist soil, so let the top 1 to 2 inches of soil dry out between waterings. Indoors, this will probably mean watering once every 2 to 3 weeks—but be sure to check regularly!
If you're using the stem, you can also root it in water. It'll generally take about two to three weeks for your jade cutting to grow roots.
Place jade plants in indirect sunlight.
Too much direct sunlight can scorch the leaves of young jade plants or cause the leaves of mature plants to develop red tips. Not enough sunlight can stunt their growth or cause them to look leggy and stretched out.
A healthy jade has erect stems and firm foliage that points outward, upward, or slightly downward. But when a plant is under stress, the young, soft stems may droop, and the foliage may hang limply, like fallen dominoes.
Shorten Leggy Stems
If an entire plant is leggy, you can cut up to one-third of each stem just above a node to encourage bushier growth. Avoid overfertilizing and provide bright indirect sunlight. You may also have a healthy stem that is much longer than the others and skews the general symmetry.
Simply select an area where you want your plant to branch out, and prune it off. For example, look at the photo below. Prune each branch just a little bit above a set of leaves (where the red line is). Wherever you cut it off, you will get new branches forming right underneath that point.
Jade needs lots of light—at least 4 hours per day in a south-facing or west-facing window. Keep soil moist but not wet during the growing season (spring and summer) and let the soil dry out during the dormant season (fall and winter).
The low-maintenance method involves snipping a cutting at the base of a leaf and placing it in fresh spring water in a glass vase where it will then grow roots. This is the easiest houseplant you'll ever have since it's impossible to kill, never has to be fed, and isn't overly sensitive to light.
Some plants can be propagated from just a single leaf. Many of these plants have compressed stems, making it impossible to take stem cuttings. These include African violets, bush-type peperomias, and Sansevieria. Some succulents, such as jade plant and jelly bean plant, can also be propagated from a single leaf.
Some people root a single leaf in water. That's fine, but if the leaf isn't attached to a piece of stem, it'll remain just a rooted leaf that doesn't grow any further.