Caring for Trees During Autumn: A Complete Fall Tree Care Guide
Fall tree care includes winterizing with fertilizer before the ground freezes‚ a fresh layer of mulch‚ reducing watering‚ and tree damage repair before winter storms․ Tennessee's growing zone spans from 6b in the mountains to 7b/8a in Memphis and Chattanooga‚ which leads to fall tree care from mid-September to the end of November‚ which is 8 to 10 weeks of workable soil before a tree's dormancy․
These cycles do not immediately stop with the end of summer‚ however․ Shorter days begin a process by which hormones pull chlorophyll into other parts of the tree's main branches and the tree's leaves change color and fall․ Root growth often continues into November if the ground temperature is at or above 40 °F (4 °C)․ That's the piece a lot of homeowners miss - fall isn't a shutdown period for the whole tree‚ it's a redirection․ Energy is going into root production and storage so fall is the best time to feed‚ mulch and get trees ready for their spring growth․
Fertilizing: The most critical timing consideration
In Tennessee it is best to fertilize trees sometime between the first light fall frost (early October) and before freeze-up (mid-November)․ Fertilizing trees too early may lead to new leaves that are killed by the first fall freeze․ Nutrients applied too late will not be available during the growing season due to dormancy․
Slow-release fertilizers are suggested at an N-P-K (with nitrogen first in the numbers) ratio of about 12-4-8․ Established shade trees require 2 to 4 pounds of actual nitrogen for every 1000 square feet of area in the tree's root zone during the growing season․ Trees under 5 years of age are less responsive to nitrogen‚ and overfertilizing may decrease root growth in these trees․
Soil testing through your county extension office (UT Extension offices are in every county in Tennessee) will help determine whether your soil is deficient in potassium or phosphorus․ A typical Middle Tennessee soil consists of a lot of clay and very low available phosphorus (though total phosphorus content is good)․ The clay binds it up․
Mulching: Don't Forget The Depth And Placement
The mulch thus serves three functions in fall: to insulate soil temperature‚ to regulate this temperature to avoid freezing‚ and to retain moisture so that the tree can respire․ In addition‚ mulch resists weeds competing with the tree for space in the root zone․ Mulch types that work include shredded hardwood‚ wood chips‚ and shredded leaves․
Applying the mulch correctly is more important than using the right type․ Place mulch 2 to 4 inches deep and in a ring beyond the tree's drip line (not a small circle around the tree) and 3 to 4 inches away from the trunk of the tree․ Mulch built up against the tree (a phenomenon known as mulch volcanoing) can trap moisture against the bark‚ causing fungal rot and bark beetles․
If you are planting any new trees this fall‚ mulch the area around their base with TN Nursery's shredded hardwood mulch‚ and cover with living groundcovers (creeping phlox or sedge) to keep moisture in the ground and weeds out all winter long․ Plus‚ their foliage is attractive and better-looking than bare soil where the tree has shed its leaves in winter․
Reduce watering‚ but do not stop altogether․
Trees are still thirsty going into fall․ Although less water is eventually used by trees since transpiration stops once the leaves start changing color and falling off the tree‚ do not cease irrigation once the weather turns cool․ Trees that enter the winter with dry roots have a difficult time in the winter‚ and Tennessee winters feature both a hard freeze and no snow cover․
Taper watering․ Water as regularly as in summer but reduce the amount of water used․ In October‚ water every 10 -14 days but reduce if it is rainy․ Watering may be the last thing done in late November with a long soak before the ground freezes․ This is especially important for anything planted within the last two years‚ because roots may not yet have penetrated it․
Push a screwdriver or soil probe 4-6 inches down into the soil․ If it goes down easily‚ the soil is moist enough to plant․ If it meets real resistance‚ then the tree needs watering․
Pruning: What Fall Care Guides Don't Cover
Most fall tree care articles discuss fertilizer‚ mulch‚ and watering․ Storm damage prevention is also part of fall tree care‚ but it is not mentioned in most fall tree care articles․
Heavy structural pruning should be done in the late dormant period of winter․ This minimizes the rate at which wounds may not heal; if the pruning is done while the tree is dormant‚ then the wound should have time to heal before the tree needs to grow in the spring․ Dead‚ cracked‚ or otherwise weak branches should be removed in autumn before the winter ice storms and heavy wet snows in Middle and East Tennessee from December to February․ Such limbs unable to withstand the winds of a storm collapse under the weight of the ice‚ taking normal wood and buildings with them․
Walk around your yard and look up․ Dead limbs typically do not have bark or have gray‚ brittle wood․ Everything that overhangs a roofline‚ a driveway‚ or a fence should be dealt with now before the first ice․
Notes specific to this species:
Different trees start fall dormancy at different times․ For example‚ sugar maples‚ a common ornamental tree in Tennessee yards‚ should be better fertilized in late September because they are going into dormancy sooner than oaks and other trees․ Evergreens such as eastern red cedar or white pine‚ which do not change color or shed leaves or needles during the winter months‚ continue to lose moisture through transpiration and should be watered frequently throughout the fall‚ unless the ground is frozen․
The newest trees‚ whatever the species‚ always need the most care and attention․ All trees‚ whether purchased from the TN Nursery or other sources‚ need an extra year or two to get settled․ All receive a larger mulch ring‚ more regular moisture checks‚ and fewer fertilizer applications than trees already established in a yard․
Bringing It Together
None of this takes all that long․ A little fertilizer․ A little mulch․ Resetting the irrigation timer․ Checking for broken branches․ A little dormant season insect and disease control on the weekend․ All of these and most everything a tree needs to make it through the Tennessee winter can be done way in advance․ The trees which are having the hardest spring are the ones which were dry when dormant‚ didn't have mulch covering them‚ or have that unseen broken limb crippling them․ A little attention for a few weeks will give us a more strong landscape when the weather warms up․
