Growing apple trees

Is it suited to your area?

Four separate things decide whether an apple tree will do well where you live: winter cold, winter chill, spring frost at bloom, and summer heat. Look at each one on its own. A good fit on one doesn’t make up for a poor fit on another.

Winter cold (your hardiness zone)

Your USDA hardiness zone describes how cold your winters usually get. It is based on the average coldest night of the year from 1991 to 2020, in 10°F zones split into 5°F half zones ^[1][2]. It tells you whether a tree is likely to survive winter. Because it’s based only on winter lows, it says nothing about summer heat, chill hours, or spring frost, and it isn’t a planting calendar ^[1].

Apple varieties are commonly rated somewhere between zones 3 and 8, and the range depends on the variety. Utah State lists ‘Honeycrisp’ for zones 3–6 and ‘Granny Smith’ for zones 5–8 ^[3]. In the coldest parts of the country, choose from varieties proven in zones 3 and 4 ^[4].

Winter chill

Apple trees need a certain amount of winter cold before they can leaf out and bloom normally. This is usually counted as hours below 45°F from November through March ^[5]. Varieties bred for the North need a lot: ‘Honeycrisp’ needs roughly 800–1,000 hours ^[6], and some northern commercial varieties need well over 1,000 ^[5]. Low-chill varieties such as ‘Anna’ and ‘Dorsett Golden’ need about 350–400 hours ^[5].

Texas A&M suggests choosing a variety whose chill need is within about 150 hours of what your area usually gets ^[5]. With too little chill, bloom is weak and drawn out, and several short winters in a row can badly stress a tree. A variety with too low a chill need can bloom early and lose its flowers to a late freeze ^[5].

Spring frost at bloom

Frost at bloom is a common reason a healthy tree has few apples. In Pennsylvania, most apple trees bloom at about the time of the average last spring frost ^[7]. Open flowers start to be damaged at about 28°F, and a few degrees colder can kill most of them ^[8][21].

Where you plant matters. Cold air drains downhill and settles in low spots, so avoid frost pockets at the bottom of a slope ^[6][21]. A warm south or west wall can push an early-blooming variety into flower too soon ^[3].

Summer heat

Apples are grown in hot-summer areas as long as their chill needs are met. Warm nights while fruit ripens can leave red varieties poorly colored, but they still taste fine ^[5]. In humid areas, fire blight is a bigger problem, so disease resistance matters more there ^[5].

Seasons of the tree

How much cold an apple tree can take depends on its stage ^[8]. The ranges below come from Washington State University research on ‘Red Delicious’ buds. Each pair is roughly the temperature that killed 10% and 90% of buds after 30 minutes ^[8][9]. ‘Golden Delicious’ was about 1°F hardier and ‘Rome Beauty’ about 2°F hardier until petal fall ^[8]. Treat the numbers as approximate: a spell of cool weather before a frost makes buds hardier, and buds that open slowly often survive colder nights ^[8].

• Dormant (winter). Closed buds are the hardiest stage ^[8]. Penn State notes dormant buds can take about 10°F ^[7].
• Bud break (silver tip to half-inch green). About 10% loss at 15–23°F, depending on how far buds have opened, and about 90% at 2–15°F ^[8][10].
• Tight cluster. About 10% loss at 27°F and 90% at 21°F ^[8]. A University of Minnesota chart puts the 10% level at 25°F ^[6].
• Pink to full bloom. About 10% loss at 28°F and 90% at 24–25°F ^[8][9]. Penn State puts full-bloom kill at about 27°F ^[7].
• Petal fall and small fruit. About the same as bloom, and all varieties are equally tender after petal fall ^[8][12].
• Thinning, 4–6 weeks after full bloom. See below ^[3].
• Fruit growing and harvest. Varieties ripen from early summer to November ^[3][5]. Ripening apples start to freeze at about 28°F and can take about 4 hours at that temperature before serious injury ^[16]. They don’t need frost to ripen ^[17].
• Leaf drop. Leaves fall and the tree goes dormant again.

Two things blur these numbers in a backyard. On clear, calm nights, buds and leaves can be several degrees colder than the air temperature a weather station reports, up to about 5°F ^[11][20]. And a tree needs only a small share of its flowers to make a crop: Utah State notes apples may need only 10–15% of buds to survive for a full crop ^[10]. Frost damage can hide in the center of the flower, even when petals look fine ^[21].

Protecting blossoms. For a small tree, a sheet, burlap, or frost cloth put on in the afternoon and reaching the ground holds in some of the soil’s warmth. Take it off late the next morning, and keep plastic off the blossoms ^[12]. Watering the ground earlier that day helps the soil store heat ^[12]. Covers help on clear, calm nights but do little on windy nights when a cold air mass moves in ^[11]. Iowa State cautions that there often isn’t much a backyard grower can do once buds have swelled ^[13], so think of a cover as a small help for a small tree.

Thinning. When the young apples are about marble size, 4–6 weeks after full bloom, keep the largest apple in each cluster and space the ones you keep about 6–8 inches apart ^[3][14][15]. Thinning gives bigger apples, keeps heavy crops from breaking limbs, and helps the tree form flower buds for next year ^[3][15].

Weather that matters

Spring frost is covered above. In summer, young trees need steady water while their roots grow. For first-year trees, Texas A&M suggests about 7 gallons a week in spring, rising to about 21 gallons in midsummer, with more in the second year. Adjust for heat, soil, and rain ^[5]. Push a finger into the soil near the tree before you water; if it’s still moist, wait.

Pruning

Prune in late winter or early spring, after the coldest weather but before growth starts ^[14][3]. Begin shaping in the first late winter after planting ^[3]. Most home trees are trained to a central leader: one main upright trunk with tiers of side branches, shaped a bit like a Christmas tree so light reaches the whole canopy ^[5][3]. Side branches that grow out at a wide angle make stronger limbs ^[5]. For hands-on steps, look for a pruning demonstration from your state’s extension service.

Harvest

Apple varieties ripen from early summer to November, so there’s no single harvest date ^[3][5]. Signs that apples are ready:

• The background color, the part of the skin that isn’t red, turns from green to yellowish ^[5][14].
• The seeds are brown ^[3][17].
• The flesh tastes sweet rather than starchy ^[14].
• The apple comes away with a gentle lift and twist, without breaking the short twig it grows on ^[3].

Red color alone can fool you, since some varieties turn red before they are ripe ^[17].

If a freeze below about 28°F is forecast and apples are nearly ripe, pick them and let them finish in storage ^[17]. If apples freeze on the tree, leave them alone until they have fully thawed; handling frozen fruit bruises it deeply ^[16].

Varieties

Choose in this order: winter cold (zone), chill hours, and bloom time compared with your spring frosts. Then weigh disease resistance, taste, and when you want to pick. Plant at least two varieties that bloom at the same time within about 100 feet of each other, or have a crabapple nearby ^[14][3]. Some varieties, including ‘Jonagold’, ‘Mutsu’, and ‘Winesap’, make poor pollen and can’t pollinize other trees ^[3]. ‘Gala’ and its look-alike strains can’t pollinate each other ^[5].

A few examples, not a recommendation list:

• ‘Honeycrisp’: zones 3–6; ripens mid-September to early October in Utah; needs about 800–1,000 chill hours ^[3][6].
• ‘Liberty’: listed for zone 4 in Maine; very resistant to scab, fire blight, cedar apple rust, and powdery mildew; ripens mid to late September in Pennsylvania and around September 10 in central Missouri ^[4][18][19].
• ‘Gala’: zones 4–8; ripens in September in Utah ^[3].
• ‘Golden Delicious’: zones 4–8; partly self-pollinating; ripens late September into October in Utah ^[3].
• ‘Granny Smith’: zones 5–8; ripens late, from late October, and may not ripen before frost where seasons are short ^[3][4].
• ‘Anna’: about 400 chill hours; ripens in late June in Texas; plant it with ‘Dorsett Golden’ as a pollinizer ^[5].

Common problems

The tree blooms but sets little or no fruit

What it looks like: Plenty of flowers, then few or no small apples a few weeks later.

Likely causes: No second variety blooming at the same time, or frost during bloom ^[3][14][8].

What to do: Plant a second variety with the same bloom time, or a crabapple, within about 100 feet ^[14][3]. Log bloom in the app so you get frost alerts at that stage.

When to ask an expert: If you have a pollinizer and no spring frost and the tree still doesn’t set fruit.

Flowers look damaged after a cold night

What it looks like: A day or two after a frost, flower centers turn brown or black. Petals can look normal ^[21].

Likely causes: Temperatures near or below about 28°F while flowers were open ^[8][21].

What to do: Wait and see. A tree needs only a small share of its flowers to crop ^[10]. Check again in a week or two for small apples forming.

When to ask an expert: If young shoots or bark are also damaged.

A heavy crop one year, a light one the next

What it looks like: The tree swings between big and small crops, often with small apples in the big years.

Likely causes: Too much fruit in one year. Thinning helps the tree form flower buds for the following year ^[3][15].

What to do: Thin to one apple per cluster, 4–6 weeks after full bloom ^[3].

When to ask an expert: If the pattern continues after two seasons of thinning.

Twigs and limbs dying back

What it looks like: Shoots and branches die back from the tips, sometimes spreading down into larger limbs.

Likely causes: Fire blight is a common cause, especially in humid areas, and it can kill a tree ^[5].

What to do: Prune out infected limbs, go easy on nitrogen fertilizer, and choose resistant varieties when you plant ^[5].

When to ask an expert: Before you prune a large limb, or if dieback spreads quickly. Your county extension office can confirm the cause.

Apples froze on the tree

What it looks like: After a hard freeze, apples feel hard like ice, then soft or browned inside once thawed.

Likely causes: Several hours at or below about 28°F ^[16].

What to do: Don’t touch frozen apples until they have fully thawed. Fruit from a short, mild freeze may be fine to eat soon but won’t store long ^[16]. Next time, pick nearly ripe apples before a hard freeze ^[17].

When to ask an expert: If many apples brown inside after thawing.

Related plants

Pear is apple’s closest relative in the catalog. Gardenplanner gives general guidance for pears for now.