It was kept alive even with roots this rotten. How was that done?

Clivia root rot

1. 
   

   Take the clivia with rotten roots out of the flower pot, gently remove the soil, then rinse the roots clean with water, and use scissors to cut away the rotted roots completely. Then apply plant ash or fine stove ash to the wounds.

   
   

   
   

2. Soak the cleaned roots in a 0.1% potassium permanganate solution for 5 minutes, then dip them in a little sulfur powder, plant ash, or carbendazim, any of these will do.

3. Control watering, place the clivia in a cool place to air for 1~2, do not let sunlight shine directly on the leaves, and it is best to cover the leaves with newspaper.

4. After airing, plant the clivia in coarse river sand or sphagnum moss; the editor used sphagnum moss~ After 15-50 days, plump white new roots will grow.

5. Note: Clivia root rot varies from case to case; sometimes the roots are only slightly rotten, while other times all the roots have rotted away completely (as shown below). If all the roots have rotted, there is still a chance to save it. Follow the root rot cleanup procedure, and after disinfection, insert it into plain sand to encourage sprouting. Generally, after about 2 months it can still grow new roots again.

Spider plant root rot

1. 
   

   If a spider plant shows signs of root rot, promptly place it in a ventilated spot with bright, indirect light. Be careful not to expose it to strong sun; basically, two hours of soft sunlight outdoors each day is enough, and the root rot will gradually improve.

   
   

2. If the spider plant's root rot is fairly severe, you need to "take drastic action." First, take the spider plant out and wash the soil off clean.

3. Cut away all the rotted parts of the spider plant, and remember to disinfect the knife beforehand.

4. After disinfecting the spider plant, place it in a cool place to dry, then apply rooting powder, and transplant the spider plant into fresh potting soil.

5. If it is a hydroponic spider plant with root rot, besides following the above steps, you also need to disinfect the container holding the spider plant. From then on, when changing the water, be sure to rinse the slime off the spider plant's roots with water. Do not fertilize for one month after restarting hydroponic culture; after one month, you can apply a little nutrient solution.

Source: Huabaike