If it is summer and hot and dry, they appreciate a drink. Soil moist, not wet. Do not stand plant in water. Let soil dry out between watering. They are a tropical plant so like heat and lots of light. The bulbuous root needs to be exposed too.
@mgrose well done you for growing a tropical plant in a cold climate from seed. They are slow growing. Treat it like a cactus, warmth, good light.Very little water in Winter when growth slows, increase water in Summer. Over watering is the biggest killer of Desert Rose. Good luck. @wesleybrian