I have been growing orchids for 50 years, and I have done my share of abusing plants, whether that be due to lack of knowledge or inattention. Below is what I have found to be the most reliable way to rescue plants that have lost their root systems:

• Completely immerse the bare-root (OK, no-root) plant for several hours in water containing 1 or 2 tablespoons of Kelpak per gallon.
• Presoak your potting medium of choice with that same solution.
• Pot up the plant normally and stake it (I use bamboo skewers from the grocery store) so it cannot wobble, as that discourages root growth.
• Water it in with the same Kelpak solution.
• Invert a clear plastic bag over the plant and pot to trap the humidity, but don’t seal it. With no roots, the plant cannot take up water, but it can still lose it through the leaves, so this slows the desiccation process to give the plant time to grow roots.
• Place the plant where it is quite warm and very shady (any direct sun can turn this into a “broil-in-bag” scenario). Applying bottom heat with a seedling heat mat is also a great help.
• The next two times the plant needs to be watered, use 1 tablespoon/gallon Kelpak solution.

In a few weeks, you should see nice new roots emerging, and once they have “taken hold” of the medium, you can return it to your regular culture. Add 1 tablespoon/gallon Kelpak monthly to your routine watering and feeding regimen.