Even if most of the layout objects are filled with flat and well chosen colors, it happens that we need more complex visual effects. Gradients that can be of two- or n-color and pattern fills that can be made of very complex shapes are some of the options that Scribus provides.
Of course, flat colors are not the only fill that you can add. We generally use flat colors, but gradients are used in some cases too. The problem with gradients is that they are not easy to print and readability can be worse. Beginners often use gradients to fill areas and backgrounds. Of course, it is possible, but where another solution could be used, it should be used.
In Scribus, gradients will be made of swatch colors from the document color list. Unfortunately, gradients cannot be added to this list. So, if you need to use the same gradients several times you should consider:
Seeing if the gradient cannot be part of a master page
Adding the frame with the gradient...