After applying Pro-Sol All Purpose Fertilizer 20-20-20 you should wait anywhere between 12-24 hours before watering your lawn.
Per an article by Summer Winds Nursery: “Adeniums are naturally slow growing mostly due to their need for minimal water. This makes for their interesting and unusual growth forms. Water them according to the growth rate and shape you desire. Flowering generally begins late winter or early spring, often before the plant leafs out. It may stop during the hottest part of the summer (mid-May thru June), and then continue to bloom again into the fall.” It can be fertilized full strength but usually from April to October. You may be able to use Pro-Sol All Purpose Fertilizer 20-20-20 but it might be easier to use a 10-10-10 like Bonide Liquid Plant Food. If you are dealing with any issues you’ve never had with this plant before, we would recommend contacting your county extension office and doing a soil test to see if your Adenium is lacking something more specific.