Have you tried using tweezers for the planting? It is easier, and you avoid that plants float to the surface when water is added.
 
Eases the planting in new and established aquariums
High quality stainless steel
For planting of both tiny carpet plants and larger plants
Also a great tool to help you place Nutrition Capsules in the bottom layer
 
How to use the product
Learn how by watching the video! Grab the plant at the root with the tweezers and press the plant into the gravel, until it’s exactly where you want it to be. Let go carefully, and pull the tweezers away. Try it next time you plant a new plant. The tweezers are also indispensable when cutting top shoots of stem plants and you wish to replant them next to the old stems.