Although some turfgrass species are more tolerant of shade than others, most grasses prefer open sunlight. Trees and turf are not very compatible. Not only does the tree canopy block most of the sunlight, it’s root system is usually the main benefactor in the competition for water and nutrients. Grasses convert light into carbohydrates through photosynthesis. When light is reduced,  carbohydrate production is diminished ultimately reducing vigor and health.

Turf species selection. By and large, most Kentucky bluegrass varieties  do not  do well in shade. Lawns sodded with Kentucky bluegrass take on an instant beauty. Not long after, shaded and partially shaded areas become quite thin. The fine-leaf fescues like creeping red fescue and chewings fescue and rough bluegrass ( Poa trivialis) perform better in shade situations. Select a seed mix that contains at least 50% fine fescue.  Late summer ( Late Aug through mid Sept) is the best time to seed shaded areas. In fact, regular seasonal overseedings may be required in order to maintain turf density.

Remove old, overgrown or nonessential trees from the landscape. Prune the lower limbs and interior branches of existing trees and shrubs. Not only will pruning increase available light , but it will also improve air circulation which will in turn reduce potential for disease development. Where possible, root prune trees to minimize nutrient and water competition. Clean up fall leaf debris to prevent turf suffocation. 

Increase mowing heights in shady areas. Generally, shaded turf should be cut approximately  1 inch  (2.57cm ) higher than open sunny areas of the lawn.

Reduce nitrogen fertilizer rates in shade.  Shaded turf  is growing less vigorously than that in open areas so the requirement for nitrogen in particular is about half the normal rate. Use efficient slow release nitrogen or natural organic fertilizers at a rate of 2lb N/ 1000 sq ft per season in these sensitive areas. Try to avoid summer fertilization.

Maintain good surface drainage.  Periodic spring or fall aeration may be required for adequate movement of air, water and nutrients into the soil.

Alternate groundcovers.  In some situations, where shade is so dense,  turf will simply not survive. Trees like Norway maple have such a thick canopy and shallow roots that growing acceptable turf cover is next to impossible. Consider alternate plant materials like Pachysandra, Periwinkle, Hosta or English Ivy. Decorative mulches can also be utilized in these areas.