Why grass will not grow under your shade tree.
Simply stated its "survival of the fittest". The trees
out compete turf grasses for all the resources necessary for life. Turf grasses grow best in full sunlight. Under trees, 95%
of the sunlight is either reflected or used by the tree for photosynthesis. The quality of light reaching the ground under
the tree is different than what is available in full sun. Grass plants growing in shaded areas react with a biological attempt
to find more light compared to grass plants growing in full sun. Grass plants in the shade will be longer, thinner and less
vigorous. These leaf changes will result in reduced tolerances to heat, cold, drought, wear and disease. Lack of vigor
will affect turf density allowing weeds to move into the thin areas.
What would seem to be the most obvious resource in short supply would be light. While the area under the tree can
be shady, it is rarely too shady, to grow turf. Little is required to germinate grass seed. The right amount of moisture,
the right amount of heat and grass seed will germinate even with no light and no nutrient. Mother Nature designed her grass
seeds to sprout in the deep shade of established grasses. Young grass plants can tolerate lower light conditions; however
as grass plants mature more sunlight is required to maintain health and vigor. In full sun areas, grass blades reach for the
sky to absorb the sunlight and thrive. In heavy shaded areas, the maturing grass plant is weakened by the lack of quality
sunlight and suffers. Then, to complicate matters, an already weakened grass plant is forced to compete with an established
shade tree for food and water.
How to keep
the grass growing under your tree.
sunlight intensity and duration of quality light reaching the grass plant is important. The more time the grass plant has
in full sunlight, the better it will perform. Pruning lower branches to raise the canopy will increase full sun exposure and
allow more wind movement helping to reduce humid conditions that can stimulate turf disease. Re-seed shady areas three times a year (spring, summer, and fall) rotating youthful, vigorous, low light tolerant grass
plants into the maturing turf stand weakened by low light conditions.
Use shade tolerant turf grass varieties. Uncle’s Shade Mix is a blend of shade and disease
tolerant turf grass varieties with lower water and nutrient requirements.
Water-Water-Water! We all know how difficult it is to keep the portion of the lawn in the sun moist where the
only water consumer is the delicate root system of the turf. Imagine how much water it takes to sustain a full-grown tree
having several acres of leaf surface from which water evaporates. In the spring, with frequent rains, the shade tree and grass
are good neighbors, plenty for everyone. However, when spring rains stop and summer heat sets in, the trees get very unfriendly.
A large shade tree can use hundreds of gallons of water a day leaving a little moisture for the turf grass. Water shaded
grass areas frequently in summer to keep the grass growing.
Compensate for unfair advantages. Make the soil under your shade trees less compact and increase its water holding
capacity by core aerating and filling the aeration holes with PrimeraFC Field Conditioner. PrimeraFC is a natural porous ceramic granule
having incredible water holding capacity with the ability to relief compaction when tilled into the soil structure. Re-seeding
can be done at this time using Uncle's Shade Mix, at heavy rate, covering seed with additional PrimeraFC.
Apply Loveland Golf Course Starter fertilizer to replace depleted nutrients and stimulate root growth.
Uncle’s Tip: Fall overseeding for
heavy shaded areas, under certain big trees, can be more successful when dormant seeded after the leaves have fallen in late
fall or winter months. Weather permitting remove fallen leaves from the area to prepare the soil. Apply Uncle's Shade
Mix, at heavy rate, covering seed using spaghnum peat or PrimeraFC. Apply Loveland Golf
Course Starter fertilizer in April. Avoid pre-emergent herbicides over dormant seeded shady areas. Crabgrass
loves the sun and heat, and you are not likely to have a huge problem with crabgrass in heavy shade.
Winter weather will not harm dormant seed. Seed will germinate in the spring as
soil temperatures warm.
large tree roots?
Unchecked over the
years, soil erosion, can expose shallow tree roots. Bare soil erodes quickly with no grass roots to hold soil in place. Top
soil can be hauled in to cover exposed roots, but too much soil can be damaging for the tree. Gases must pass from the
air to the roots and from the roots back to the air. Too much soil pack can create real problems for the tree so, be careful!
Some surface roots can also be removed. Large surface roots are more for anchorage and with expert help, you may be able to
remove a few. Always contact an arborist for advice on removing tree roots.
If all else fails, start a shade garden. Hosta, astilbe, hydrangea love the shade.