Why the Best Month to Plant a Tree Here Is October

The garden centres are busiest in April and the plants would rather go in six months later. That gap costs Sandy Springs homeowners money every year.

What UGA says

UGA Extension’s guidance is direct. Fall is the ideal time to plant most woody trees, shrubs, vines and groundcovers as well as herbaceous perennials in Georgia. Temperatures are moderate and less stressful to plants than the hot temperatures of late spring and summer. Plants require less frequent irrigation and are less likely to suffer sun scorch or heat-related stress. And fall-planted ornamentals continue to develop a strong root system even after their tops have gone dormant.

The extension guidance goes further and recommends fall and winter planting of woody ornamentals and herbaceous perennials outright, on the reasoning that there is less demand for water and nutrients by the top of the plant and more energy and food available for root growth. While the crown shuts down for winter, the roots keep growing.

That is the whole argument, and it is a root argument rather than a weather one.

What it means in practice here

A plant installed in October has roughly seven months of moderate conditions to establish a root system before it meets its first Georgia July. A plant installed in May has about six weeks.

The Piedmont climate makes that difference sharper than it sounds. NOAA’s 1991 to 2020 normals for the Atlanta area put the average July high at 89.1 degrees, with about 35.7 days a year at or above 90. That is the load a newly planted root ball has to carry, and the size of the root system when it arrives is what decides the outcome.

There is a second, quieter benefit. Georgia law limits outdoor landscape irrigation to the hours between 4 p.m. and 10 a.m., with an exemption for new and replanted plant, seed or turf during installation and for 30 days after. A plant that goes in during October needs materially less water through that 30-day window than the same plant in May, which turns the exemption from barely sufficient into comfortable.

The window

October through early December is the centre of it in Sandy Springs. The soil is still warm enough for root activity, the air has cooled, and the plants are winding down above ground.

It runs into winter for a lot of material. Georgia soils rarely freeze, and dormant woody planting through the colder months is an established practice in the southeast. What it will not tolerate is working saturated clay: late winter and early spring are the wettest ground here, and machinery across a wet lawn does long-term damage to the surface layer that makes the whole yard plantable.

Where fall is the wrong answer

Turf runs on its own calendar and it does not match.

Warm-season grasses go down when soil temperature at four inches is consistently 65 degrees and rising, which means May and June for sodding, sprigging and plugging. UGA warns that dormant sodding of warm-season grasses is the riskier option, with increased winter injury observed on zoysia and centipede against bermuda when sodded late.

Tall fescue does align with fall: September to October, or late February to March. UGA notes fescue sod in winter is acceptable because it is a mature plant going in.

So a project that includes both new beds and a new warm-season lawn is a project with two installation dates, and that is worth knowing before anyone promises a single completion week.

Booking, which is the practical constraint

Fall is the right planting season and it is also the busiest booking period of the year for competent crews. A project intended for October is a conversation in August, not a phone call in late September.

That is the most common avoidable disappointment in residential landscaping here: a homeowner decides in autumn, finds nobody free until December, and either accepts a compromised date or waits for spring and hands the plants a summer they were not ready for.

The planting calendar guide sets out the whole year month by month, including what can be built when the ground is too wet to plant.

Sources: UGA Extension Circular 873, Best Management Practices in the Landscape. UGA Extension Bulletin 1533-2, Lawns in Georgia: Establishment. NOAA 1991 to 2020 climate normals for Atlanta Hartsfield-Jackson. O.C.G.A. 12-5-7.