Ahead, garden and lifestyle expert Carmen Johnston shares her tips for flourishing ferns throughout the season. Boston ferns have arching, cascading fronds that want to spill over an edge, and they want shade,” says Johnston. If you’re getting started with ferns after spring has passed, Johnston recommends planting containers in the shade with autumn ferns. Grow in Suitable ConditionsFerns thrive when planted in filtered or dappled light, or in a spot with morning sun and afternoon shade, Johnston says. Week Three: Water ferns with a mixture of water and (one tablespoon to one pitcher of water) to boost magnesium and keep leaves green.