Most shade plants prefer moist soil.
Mulching is a good way to maintain lots of organic material in the soil. Adding 4 to 6 cm of compost in spring will help to retain moisture, keep down weeds and increase the proportion of organic matter in the soil. For native plants, it is enough to add compost once a year, because overly fertile soil will adversely affect their natural growth. More demanding plants will benefit from a springtime application of fertilizer that will nourish them for 2 or 3 months.