When to Plant Trees and Shrubs: Fall Dates Counted From Your Freeze

Plant shade trees, ornamental trees and most shrubs in fall, early enough for roots to grow before the ground freezes, or in early spring before the buds open. Extension services say to finish fall planting about six weeks before the first hard freeze, to plant evergreens earlier than that or wait for spring, and to avoid midsummer. Counted from NOAA normals, the six-week date falls on September 23 for the median of the 37,563 lower-48 ZIP codes that have a hard freeze, yet nine published calendars let planting run 3 to 8 weeks later, and the median of the 35,804 ZIP codes that cool below 50°F gets there on October 28.

This guide covers landscape trees and shrubs. Fruit trees have their own dormant-season rules, which our fruit tree planting guide covers with spring and fall dates by city and zone. Here we turned the fall rule into dates for 30 cities and 40,557 ZIP codes using NOAA 1991–2020 normals¹ and tested it against nine published last-planting dates. Air temperature stands in for soil temperature throughout, because our NOAA data has no soil readings.

How the plant is sold changes the window

Container-grown plants arrive with their roots in a pot, balled-and-burlapped (B&B) plants with a dug root ball, and bare-root plants with no soil at all. The University of Maryland says most B&B and container-grown trees can be planted any time the soil is not frozen, while bare-root plants are shipped and planted dormant and fail mostly through root drying.⁸ Table 1 sets out what each form gets in the sources we read.

Purdue’s advice for fall is to choose B&B or container plants over bare-root stock, and to plant bare-root plants only in late winter or early spring while dormant.⁹ Bare-root fruit trees follow the same rule, with dates in the fruit tree guide linked above.

Fall: finish about six weeks before the freeze

Four extension sources give nearly the same rule. Purdue’s forestry specialist describes the common recommendation this way:³

approximately six weeks between planting and the first hard freeze

UMass says plants need at least six weeks to establish before the ground freezes and suggests planting by Columbus Day weekend.⁴ UNH asks for six weeks of mild weather for root growth and offers early October as a deadline.⁵ The wording differs in one word that matters: Purdue counts to the first hard freeze, while UMass counts to the ground freezing, which comes weeks later. Roots keep growing, UNH adds, until the soil dips below 40°F.⁵

Table 2 counts back six weeks from NOAA’s median first hard freeze (28°F; our frost and freeze guide explains the term). It also shows the day the normal air temperature falls below 50°F and 60°F, the soil lines we test below.

Across the 37,563 lower-48 ZIP codes with a median hard freeze, the six-week date has a median of September 23, and the middle 80% run from September 1 to October 23. It falls before September 1 in 9.6%, in September in 56.5%, in October in 27.5% and in November or later in 6.4%. The other 2,994 (7.4%) have no median hard freeze at all, and Sacramento and Phoenix are among them. The six-week date falls after Columbus Day (October 12) in only 19.2% of those ZIP codes, so UMass’s New England rule of thumb is a late one for most of the country.¹

Published last dates against our counts

We took nine last-planting dates from extension services that name one and counted them against three markers for the nearest NOAA station: six weeks before the first hard freeze, six weeks before the day the normal air temperature falls to freezing (our stand-in for the ground freezing), and the day the air falls below 50°F, or 60°F for evergreens. The 50°F line is Missouri Extension’s:¹³

If your soil is consistently 50℉ or higher, you are good to plant.

Davey Tree, a commercial tree-care company, uses 50°F for deciduous trees and says to avoid planting evergreens when the soil is below 60°F.¹⁴ Table 3 shows the result.

The strict count is early in every case: all nine published dates fall 21 to 59 days after six weeks before the hard freeze, so planting by that date satisfies every source. The count from the ground-freeze stand-in runs from 28 days after a published date to 19 days before it in the eight places where the air average reaches freezing, which makes it too erratic to use. The soil line lands within nine days of six of the nine, and misses Wisconsin’s two evergreen cutoffs by 24 and 17 days and Iowa’s early November by 19. The 60°F evergreen line fits two of the four evergreen dates, Ames and Amherst. Our reading is that the six-week date is the safe date and the 50°F day is the outer limit for deciduous trees where you can water, but a soil thermometer beats both.

Evergreens: earlier in fall, or spring

Evergreens keep their foliage, so they keep losing water all winter while frozen ground blocks the roots from replacing it. Wisconsin’s plant clinic calls the damage winter burn, sets the cutoffs we tested in Table 3, and says summer planting is possible with water:⁶

Evergreens can be planted in the summer if you provide supplemental water.

The same page says to plant evergreens in early spring before the buds break or in August and September.⁶ Iowa State calls mid-August through September an excellent time for pine, spruce and other evergreens, and says evergreens planted in late October or November may be too late.⁷ UMass says pine and spruce do well planted before the end of September but to wait until spring for rhododendron and yew.⁴ The University of Maryland says broadleaf evergreens are best planted in spring, though mountain laurel, boxwood and hollies can go in early fall with deep watering and mulch.⁸

The sources do not all agree. The Southern Group of State Foresters says evergreens should only be planted in late winter or early spring,¹⁵ and Holden Arboretum in northeastern Ohio plants evergreens in late summer, describing a white spruce planted after Christmas into a pre-dug, straw-covered site.¹¹ An Ask Extension reply to a Howard County, Maryland, question adds that the later in fall an evergreen goes in, the greater the risk of winter damage, even if it only shows in spring.²⁰ Our counts put the 60°F line on September 18 to 24 in Green Bay, Madison, Ames and Amherst; the median ZIP code reaches it on October 4, and 9.7% reach it before September 15.

Trees that wait for spring

Some species root slowly or have fleshy roots and do poorly when planted in fall. Illinois Extension relays the Morton Arboretum’s list of slow-to-establish trees and a list that suits fall,¹⁰ and four other sources name their own. Holden adds a number: dogwood, redbud, beech, sycamore and others need soil of about 56°F or higher to grow new roots, which is why it calls them challenging to dig after early September.¹¹ Table 4 sets the lists side by side, and the disagreements are as useful as the agreement.

Spring: before the buds open

Spring planting works when the ground is workable and the tree has not leafed out. Holden says to plant in late March through April before new shoots emerge in northeastern Ohio, because actively growing shoots leave fewer resources for roots, and that a tree losing many roots in May or early June may wilt and die.¹¹ The Colorado State Forest Service calls March 15 to June 15 another great time to plant, after early fall.¹² UNH warns that a rainy spring followed by hot, dry weather can scorch new leaves.⁵

Illinois reduces the choice to rain: the best time is when regular rainfall arrives, which in the Midwest includes both spring and fall.¹⁰ For container and B&B plants, which need only workable soil, the opening date is the thaw. Among the 19,518 ZIP codes where the normal air temperature drops to freezing and recovers, it is the day the air first averages above 32°F again: the median is March 1, and the middle 80% run from January 30 to March 22. Table 5 lists it by city. A late frost can damage new leaves and blossoms but the plant survives; our frost cover guide covers what Iowa State says about protecting them.

Summer: the risky season, and how much to water

The University of Maryland says summer planting, when plants are in full leaf, can be stressful and should be avoided if possible.⁸ Clemson says shrubs planted from spring through summer need more careful watching of soil moisture in the hot, dry season, because new shrubs have few roots to feed actively growing shoots.¹⁷ Arbor Day Foundation notes that fall planting leaves the tree an extra growing season before summer stress.¹⁹

The watering target is the same in every source: about 1 inch of water a week. Purdue says newly planted trees need supplemental water when rainfall falls short of it, and gives 5 gallons a week for every inch of trunk diameter as a starting guide.³ Illinois says to water at least weekly and skip a week that brings an inch of rain, for up to three years.¹⁰ Iowa State says to water daily for three or four days, then taper to a thorough watering every 7 to 10 days in dry weather until the ground freezes.⁷ UNH wants the soil wetted 8 to 10 inches deep once a week,⁵ and Maryland says to water through the first two years, even in winter, but not when the ground is frozen.⁸

We compared that inch with NOAA’s normal rainfall, divided into weeks. In a normal July the median ZIP code gets 0.90 inch a week, rain alone is short of an inch in 66.5% of ZIP codes and short of half an inch in 18.7%. October is drier still: the median is 0.75 inch a week, and October is wetter than July in only 30.8% of ZIP codes, so fall planting does not escape watering. Over April to October the median ZIP code has 5 of 7 months below an inch a week, 31.4% have all seven, and only 1.0% have none.

Mild winters, dry summers and USDA zones

Where the ground does not freeze, the freeze deadline disappears. In 51.8% of lower-48 ZIP codes the normal air temperature never averages below 32°F, and in 11.7% it never falls below 50°F. Clemson says fall is the best season for shrubs in South Carolina because roots keep growing through winter,¹⁷ and says container and B&B trees can go in all year but are best planted in fall.¹⁶ UF/IFAS tells Florida gardeners who cannot water regularly to plant at the start of the local rainy season and puts establishment at about 20 to 28 weeks.¹⁸ In dry-summer places the calendar is the water: Colorado’s state forest service points to September 1 to October 15,¹² and Portland and Seattle get 0.09 and 0.14 inch a week in July.

Your hardiness zone tells you what survives, not when to plant;² our zone and frost date guide draws the line. It still sorts the dates, as Table 6 and the zone chart show.

After planting: mulch and care

Arbor Day Foundation says to water right after planting, even in cold weather, and to lay a 2- to 3-inch ring of mulch without piling it against the trunk.¹⁹ Our mulch timing guide counts when to lay it. Purdue says to keep watering until the ground freezes, even after leaves have dropped, and to wrap thin-barked young trunks in late November and remove the wrap in March.⁹ Missouri says dry winter soil is a main drawback of fall planting, so water through the winter when the soil is not frozen.¹³ Perennial divisions use a similar count-back from the freeze, covered in when to divide perennials.

How we calculated these dates

Daily temperatures are NOAA’s monthly normals placed on the 15th of each month and interpolated linearly, for the station nearest each ZIP code.¹ The six-week date is NOAA’s median first 28°F freeze minus 42 days; the 50°F and 60°F days are the first days the normal daily mean falls below each line after the warmest day; the thaw is the first day it returns above 32°F. Rain is each month’s normal precipitation divided by the number of weeks in the month. The national pool is 40,557 lower-48 ZIP codes; zones are the 2023 USDA map.² Soil lags air, the 50°F and 60°F lines are soil rules applied to air, and a single year can run weeks ahead of or behind a normal.

Next steps

Find your median first freeze with the frost date lookup and your zone with the planting zone tool, subtract six weeks, and put a soil thermometer in the ground. Call 811 before you dig, as Arbor Day Foundation advises.¹⁹ For pruning timing once the plants are established, see when to prune roses and when to prune hydrangeas.