Growing an Apple Tree


An apple is a sweet, edible fruit produced by an apple tree (Malus pumila). Apple trees are grown worldwide and have been cultivated by humans for thousands of years. There are over 7,000 varieties of apples grown for reasons as wide ranging as fresh eating to cider making, so it is important to choose one that is right for your area and needs. Apple trees became popular in the 17th century after being imported to America by early settlers due to their versatility, ease of preservation, and the high value of apple cider. By the mid-1800s apple fruits, especially cider apples, would become the most common fruit grown in America. Apple cider remained extremely valuable until the prohibition era of the 1920s and 1930s that outlawed all forms of alcoholic beverages, leading to the removal of the majority of America's older cider apple orchards. Modern day apples are no less popular however and thanks to fruit historians, and avid enthusiast, many of our old heritage varieties are making a come back!




Choosing a Variety


Size


Size is an important consideration when choosing an apple tree. Apple trees can be narrow or spreading, very tall to 50’ or very manageable at 6-10’, and can be grown in containers, as landscape feature plants, or in an orchard. Modern apple trees are grafted to specific rootstocks that naturally control their size and provide additional resistance to common pests and diseases the grafted cultivar may not have the ability to defend against.

Take a look at this size chart showing apple trees grown on different rootstocks.





Pollination


Unless otherwise noted, all apples need another variety of apple nearby to cross pollinate each other. Using the apple pollination chart below to determine which pollinizer tree variety is the right choice will help ensure your orchard will be successful and productive.  Apples in the same and adjacent flower groups will reliably pollinize each other.


Example 1: Honeycrisp is a mid-late season blooming apple. It can reliably cross pollinate with apples in the mid-season, mid-late season, and late season. It cannot cross pollinate reliably with trees in the early season and early-mid season.


The pollinizers should be planted no further than pollen carrying bees will fly, with no line of sight obstruction, to ensure proper cross-pollination. That distance varies with different bees, 100’ should be a good average distance.


Triploids


Some apple trees are triploids, which have three chromosomes instead of two, and in turn are functionally pollen sterile. Triploid trees still need cross pollination to create fruit, but do not provide compatible pollen to pollinize other nearby trees. When including a triploid cultivar in your orchard make sure that the other trees in your design will be able to serve as pollinizers for each other in addition to the triploid. Common varieties of triploid apples are Gravenstein, Jonagold, Thompson's Kind, and Ashmead's Kernel. Triploids are listed in red text on our apple pollination chart.


Self-Fertile Trees


Self-fertile apple trees, trees that make compatible pollen for their own female flowers, are uncommon in apple trees, but do exist. Depending on your location a tree's self fertility may vary or even change from one region to another. Where we are based in the Pacific Northwest only the Queen Cox apple is considered reliably self fertile. Cultivars that are not self fertile here may be partially or completely self fertile in other parts of the United States. We cannot accurately answer any questions you may have about which of the apple varieties we carry may be self fertile in your area. Please contact your local extension service for more information on your specific growing region.






Ripening Time


Apple tree fruit generally ripen from mid-summer through late fall, depending on the variety and your location. As you make your selections double check that pollination needs are also met as early-flowering trees does not necessarily mean early-ripening fruit. Apples that ripen early tend not to store well and do not last long on the tree, whereas later ripening varieties tend to have longer storage times and remain edible on the tree longer. Generally speaking your apple tree fruit are ready to pick when apples begin falling from the tree. Some varieties come off the tree easily when ripe, while others do not. Some types of apple are meant to be picked early and allowed to mature in storage and some, like Gravenstein may ripen unevenly and need to be picked over a period of weeks.





USDA Plant Hardiness Zone


Apple trees are hardy to USDA zones 4-9, unless otherwise noted. This rating tells you the minimum winter temperature the plants typically survive when properly hardened off. Make sure you consult the USDA Hardiness Maps  website, which provides information on the average minimum winter temperature in your location, by zip code. Your USDA Plant Hardiness Zone does not reflect the many of the other factors in successfully growing apple trees, including length of growing season, rainfall amounts, soil quality, and chill hours. Consult your local extension service for more detailed information about your local growing region and the factors you will need to know when selecting fruit trees for your home orchard.





Chill Hours


All plants have what are called a "chilling hour requirement" in order to flower and produce fruit. Chilling hours are defined as the cumulative period of time between 45 and 32 degrees fahrenheit and vary from region to region. The majority of apple trees have a chilling hour requirement of anywhere from 500-1000 hours, with some requiring more and a few requiring as little as 200-300 chill hours to blossom and produce. Apples trees that require less than 600 chilling hours are considered "low chill" and are generally more resistant to more intense summer conditions than apples trees with higher chilling hour requirements. The general chilling hours available for you specific location can be found online or determined by your local extension office.




Where to Plant Your Tree


Apple trees need to be planted where they receive at least 6-8 hours of direct sunlight as measured in early summer(late June to early August). Sufficient sun exposure triggers the initiation of new flower buds for the next growing season, without which there will be no fruit. Fruit ripening and flavor development are also benefited by the carbohydrate production stimulated by the sun, as well as it’s heat.


Apples tolerate a wide variety of soils so long as they are well drained and moderately rich with a pH around 6.3-6.8. Improve your soil where you intend to plant by mixing an inch or two of plant based organic matter (manures are best for vegetable gardens), peat, or coconut coir into an area 1 1/2 to 2times the diameter of the needed planting hole and up to a foot deep. A2-4” deep layer of mulch (straw, leaves, or wood chips) applied after planting will continue to improve the soil.


Allow sufficient space for both the top of the tree and it’s roots when selecting the planting location. Refer to size descriptions for each variety, keeping in mind these are generally managed or pruned sizes,not maximum potential sizes. If you are planting an orchard be sure to include enough space between rows for transporting supplies in and fruit out.

 



Growing in Containers


Columnar apple trees and mini-dwarf grafted apple trees are the best candidates for growing an apple tree in a container. Dwarf grafted apple trees can also be grown in a container with annual pruning and occasional root pruning. Be aware that pots are a very different environment than planting a tree in the ground. Due to their nature pots typically have higher soil temperatures, lower soil moisture, lower water holding capacity, and limited fertility. Growing an apple tree in a container will require careful attention to location, irrigation, and require more frequent fertilization to be successful over time.


One of the benefits of growing apple tree sin containers is the ability to grow apples in conditions you may not normally be able to plant trees in. Container growing is a great solution for enthusiasts that may not have access to a permanent orchard space, adverse soil conditions, live in an urban environment, or want to grow several cultivars without having to worry about excessive fruit production and ladder work during harvest and annual seasonal pruning.


To grow an apple tree in a pot you need a final container size of at least25 gallons. Trees will grow larger in a larger container, but make sure you have the ability and tools to move the pot's heavy weight.

Do not use soil from your garden in the pot, instead use a potting soil mix with some added compost. For larger pots use a potting mix that has larger particles in addition to the smaller ones.





Care and Maintenance


Watering Your Tree


This is the most important and often the most difficult part of successfully growing plants. There are many factors, including the humidity, temperature, soil type, wind, and amount of direct sun that affect how much and how often water should be applied.


A general rule of thumb for plants in the ground is to ensure they receive an inch of water per week over the root zone. An inch of water is equivalent to about ¾ to one gallon per square foot of soil surface area. The typical three foot diameter planting hole would need 7 ½ to 10 gallons of water per week provided by rainfall and/or by the gardener.


Apply this water once a week, two times per week if soil is fast draining.This will of course depend on your own conditions and the plants you are growing! Do NOT water lightly each day because this results in a wet surface and dry root zone area. The soil should be moist but not soggy to a depth of about a foot for most growing plants. The top inch or two can feel dry, and the plant still b well watered. The trick is to have the water available where the roots are. In hotter and sunnier areas, a mulch of straw, bark, etc. can greatly ease the burden of summer watering.


For plants in containers,water until the soil is saturated and water comes out of the drainage holes. Let the container dry until the soil is dry to the touch 1-2inches down (more deep with deeper pots) and the container is lighter in weight. A plant that has wilted can be receiving either too much or too little water.


In rainy areas like the Pacific Northwest most of the plants that we offer will need relatively little supplemental irrigation ONCE THEY ARE WELL ESTABLISHED in the ground and have had a chance to develop a good root system. However even here it is important to make sure plants have regular, deep watering during the first couple of growing seasons, and the first summer is especially critical. In drier areas, or where soils do not retain water well, permanent irrigation is required.Remember that you don’t want your trees to just survive, but rather to thrive. Make sure they get the water where they need it, starting at the drip line and extending away from the tree up to several feet ( for older trees) where the feeder roots will be.




Fertilization


For good steady growth and high productivity, your trees need to have adequate amounts of various mineral nutrients. Some people are fortunate and have naturally rich fertile soil. Many soils, however, are deficient in some nutrient or another and use of fertilizers, organic or chemical, can be highly beneficial if you want your trees to grow well.


Use an all-purpose or balanced fertilizer like the organic fruit tree and shrub fertilizer.  A couple of inches of well-rotted compost on the root zone can also be an effective fertilizer. A generous leaf or straw mulch around your trees will not only conserve moisture and help in weed control, but also keeps your soil healthy by building up humus,attracting earthworms, and supporting beneficial fungal organisms. This encourages young trees to be strong, healthy and productive.


Use of concentrated products like chemical fertilizers or strong organics (for example: blood meal) is usually done from late winter through early summer. Applying fertilizer after early summer can encourage lots of soft new growth that is much more likely to be damaged by winter cold.Excessive use of fertilizer can increase disease problems on your plants and can even kill them.

As a general guide, if your tree is producing about one foot of new growth or more a year and has healthy looking foliage, it may not need much or any fertilizer.

 



Pests and Diseases

Find out what insects and diseases are typical in your area. Ask your local co-operative extension professional what the typical insect and disease issues are in your area. Then you can make selections based on resistance or tolerance information available in our catalog, or, make a plan for controlling problems you can expect with the susceptible varieties you prefer to grow. If you see resistance information about a particular disease for one variety, but not another of the same kind of fruit, then that variety may be susceptible or might not have been tested so is unknown. The following are some of the more common issues.


Anthracnose


Symptoms

Cankers in bark of stems or trunk. In spring appear as water soaked areas. During summer bark shreds and dies.


Control Methods

Excise or cauterize new lesions in June. Heat to bubble, not charred, with small torch.

Comments

Disinfect tools with alcohol between cuts when removing cankers. The fungus spreads in water so be careful to prune out cankers on in dry weather.


Powdery Mildew


Symptoms

White powdery fungus on leaves and shoots. Stunted or distorted new growth.


Control Methods

Choose resistant varieties. Life sulfur, milk solution, or potassium bicarbonate. Spray during spring and early summer. Maximize air flow.

Comments

Worse in shaded areas. Avoid excessive nitrogen fertilizer. Infections can over winter in buds are shoot tips. Prune out affect shoots and thin to maintain good air circulation.


Fire Blight


Symptoms

Shoots wither resembling shepherd’s crook. Leaves die and turn black or brown, but remain on tree.

Control Methods

Prune out all infected shoots, cutting at least 12 inches below infection. Disinfect tools between cuts. Fixed copper spray in fall and early spring, or use Bordeaux mix.

Comments

Especially common on pears in warm wet springs, but may also affect apples in bad years. Plant resistant varieties. Prune to promote good air flow.


Codling Moth


Symptoms

Worms in fruit growing to ¾ inch in length, leaving exit tunnels and abundant dark frass in the seed cavity.


Control Methods

Organic insecticides sprayed 2 weeks after full bloom. Mating disruption using pheromone traps is effective in larger orchards.

Comments

Control using organic methods requires careful timing. Clean up all fallen fruit and discard as soon as possible, do not compost.


Apple Maggot


Symptoms

Heavily tunneled fruit filled with small maggots.


Control Methods

Sticky traps and pheromone kits. Apple maggot control bags. Surround, Spinosad, or Bioneem insecticides.

Comments

Clean up and discard falls fruit immediately. Do not compost. Combine traps and control bags for greater success. Note: Apple maggots can host in other plants (e.g. Hawthorn, crapapple) and placing traps in those areas may be helpful.


Scab


Symptoms

Blackish brown blotches on leaves. Scabs on fruit.

Control Methods

Plant resistant varieties. Apply lime sulfur, sulfur, fixed copper, or Bordeaux mix whenever warm and wet conditions occur from spring through early summer. Organic bio-fungicides.

Comments

Infection occurs rapidly at temperatures over 45 degrees Fahrenheit, which is also when spraying is most effective. Clean up and discard all leaves. Do not compost.


Bitter Pit


Symptoms

Water soaked areas fruit skin followed by sunken necrotic spots and/or brownish or streaked necrotic areas inside the fruit. Spots are more numerous on the blossom end of the fruit. Spots or necrotic areas may appear either while the fruit is on the tree, or later in storage.

Control Methods

Avoid heavy winter pruning and practice summer pruning to control excessive vegetative growth. Spray fruit with calcium chloride or calcium nitrate. Avoid excess nitrogen fertilizer. Thin fruit before ripening. Apply supplemental water in dry summer years.

Comments

Bitter pit is a result of calcium deficiency in the fruit, brought on by excessive suckering/growth, trunk damage, and/or uneven irrigation. Internal symptoms sometimes may resemble apple maggot damage. Some varieties are more susceptible than others.


Wooly Apple Aphid


Symptoms

Reddish 1/8” long insects make white cottony masses on the bark, warty growth on limbs, black sooty mold on foliage.

Control Methods

Parasitic wasps can help. Dormant oil kills colonies only on branches. Sticky bands on trunk can help. Often plant needs to be uprooted and burned.

Comments

Aphids initially infest roots, especially of stressed trees. In summer migrate from roots to trunk and back. Also aggravated by a heavy insecticide program. MM111 & M106 rootstocks are resistant.


Shot Hole Borer


Symptoms

Invades apples, chestnuts, cherries and other trees. Pin size holes in trunk spring or summer. Look close to see sawdust around hole and notice fermented smell. Limbs or whole trees suddenly die.

Control Methods

No effective organic methods. Whitewash trunk and lower limbs with interior white latex paint diluted 50% with water in fall to confuse beetles next spring. Infestations bad some years. Borers live in alder and other trees.

Comments

Bark beetles sense volatile oils from stressed trees. Keep trees healthy, particularly when newly planted. Monitor and destroy infested trees. Generations occur April-May, June-July and August-September.


Deer


Symptoms

Browsed shortened branches. Leaves are obviously munched on or plants are pulled up.

Control Methods

Fences or cages at least 8’ tall. Plastic mesh, electric, or woven wire fences.

Comments

At Raintree, an 8’ woven wire deer fence has worked best. Repellents don’t work consistently and, aside from fencing, only trained large dogs patrolling the perimeter are effective.


Bird


Symptoms

Fruits disappear or have gaping holes in them. Strawberries, blueberries, cherries and filberts are most susceptible but most fruits suffer occasionally.

Control Methods

Reflective Bird Scare Tape can work well. Bird netting. Cages.

Comments

On hazelnut trees, Blue Jays start harvesting filberts when ready to pick, and so should you. Nuts dropped by jays are usually empty.


Vole/Mouse/Rabbit


Symptoms

Bark eaten in a band from soil level up to 8” and roots eaten too, usually in snowy areas with lots of mulch or tall grass at base of trees.

Control Methods

Keep mulch 4”-6” away from trunk. Keep grass short and 1’-2’ from trunk. Use vinyl tree guard wrapped around trunk until tree well-established.

Comments

Voles and mice will chew a couple inches above ground and also into the root system. Rabbits will chew up to 8” high, particularly apple trees.


Aphid


Symptoms

1/32 to 1/8” long pear shaped insects that multiply rapidly, especially on the underside of leaves and on stems. Can be pink, green, black or white. Leaves show red blisters or are curled-down and stems turn black with sooty mold.

Control Methods

Natural predators like lady bugs and parasitic wasps often provide control. Knock aphids off with water spray. Spray with Pyrethrin, Rotenone, Insecticidal Soap, or delayed dormant oil. Control ants if they are also present.

Comments

Trees can tolerate some infestation. Monitor in late spring and summer. Control is more important on new trees. Grow plants that attract predators, i.e. dill or yarrow.


Ants


Symptoms

Numerous ants scurrying up and down the tree trunk; aphids, scale or mealybug present in large numbers, lots of sticky honeydew, perhaps sooty mold.

Control Methods

Find hill and apply pesticide. Apply Tangle Trap over 2-3” wide band of paper wrapped around trunk. Eliminate other pathways into tree.

Comments

Ants nurture and protect these insects in exchange for their sugary secretions. Insects may be difficult to control until the ants are controlled.


Brown Marmorated Stink Bug


Symptoms

Poking-type feeding damage followed by decay on fruits, nuts, berries and leaves. Deformity in the healthy tissue surrounding the dead tissue. Brown spots can show up in stored fruit.

Control Methods

Monitor with traps, some broad spectrum pesticides may work. Researchers are working on finding effective controls, but no info has been released yet.

Comments

BMSB over winters in groups in dry protected areas, such as houses. If you find them on or in your home use the vacuum, squishing releases their defensive stink.  See stopbmsb.org for more info. Feeding begins in spring when the weather warms up and continues until new adults go dormant for winter.


Rust


Symptoms

Lesions on the upper surface of the leaf, or on the fruit or stems, followed by orange-ish structures on the bottom side of the leaf, or on the fruit or stems, which produce spores.

Control Methods

Copper fungicide after harvest before fall rains and again in early spring for prevention of some\ rusts. Remove and destroy infected parts of the plant. If possible select resistant varieties. Many varieties have not been studied. Cedar-apple rust is a problem east of the Rockies.

Comments

Rust diseases require an alternate host, removing the host (within 900’ radius), applying fungicides, or removing infected parts may help. Check with your extension office to see what rust diseases in fruiting plants may be common in your area, and their alternate host.


Sunscald


Symptoms

Vertical splits in bark appear spring or early summer, usually on the south or east side of the tree. Disease or insect infestations may then occur.

Control Methods

Whitewash trunk and lower limbs with interior latex paint cut 50/50 with water each fall until bark has thickened. Avoid planting in frost pockets or where water collects in winter.

Comments

Injury occurs during pattern of warm days followed by freezing nights. Sap gets stuck in trunk, freezes, then rapidly thaws in the warm sun the next day, rupturing cells.