This article by Epic Grower Company helps address several questions concerning growing adenium seedlings once they are well established (4+ months old). First desert rose seedlings require much more attention and water than mature adenium plants. Currently in south Florida we are still keeping the adenium seedling the soil wet (make sure you have the right soil so there is plenty of air in the soil to prevent root rot!).
Depending upon your location you will need to give the seedlings 10+ hours of strong natural light per day or use grow lights. At the same time keep them above 67 degrees which means in northern area you many need to get a plant warming pad just like people use when germination seeds. Seedlings are not mature until they reach about 1.5 years old. As seedlings, eh adenium plant will grow faster than mature plants if grown in the proper manner. Many of AdeniumRose adenium seedlings are over 8″ tall which caudexes of 1″ across in 3.5″ pots and now ready to be cropped in January/February depending upon the weather (these were started as seeds in June).
Yes, we still have about 400 seedlings smaller 2″ pots that were planted in late August of which 90% are ready for 3.5″ pots (these are ones one being offered at a special price at www.epicgrower.com). The 2″ pot seedlings are just now being adjusted away from constantly being in water to a moist soil mixture with plenty of air in the adenium plants soil mixture. In December 90% of adenium plants will be repotted into the 3.5″ pots. When the adenium plants were put in the 2″ pots from the germination trays the 2″ pots are then kept in tray that has a water reservoir so 50% the roots are always in water. No if done right you will not get root rot. Yes, you will lose some weaker plants (about 5%). Then main thing is to germinate the seeds in early May so the adenium seedlings are ready for the 2″ pots by July.
Once they are in the 3.5″ pots we do not all let the soil to dry out whatsoever. remember we are in a tropical environment unlike all other parts of the USA except for Hawaii and Puerto Rico. We do not get a true cold winter. A cold snap here is when the night time gets in the 50’s so you will need to adjust based on your desert rose plant growing environment. Our winters are our dry season where in other parts of the USA it the wet time of year.
Also, we continually feed the adenium plants and seedlings Dyna-Gro Grow and Dyna-Gro Tekt (alternate watering).