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, so it is important to choose one that is right for your area.
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.
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 pollinate each other. Use the apple pollination chart to determine which pollinizer tree variety is the right choice. Apples in the overlapping flower groups will pollinize each other. While some Apples, such as Queen Cox, are self-fertile, a pollination partner may increase the size and quality of the harvest.
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.
Ripening Time
Apple fruit ripen from mid-summer through late fall, depending on the variety. As you make your selections double check that pollination needs are also met. Early flowering does not imply early ripening. 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.
USDA 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. We do not have a good rating system at this time for summer patterns (long, short, hot, cool, humid, dry…), but if known, individual descriptions will indicate if a particular plant tolerates (or requires) hot or cool, long or short summers. On our web site you will find a USDA Hardiness Maps (select Growers Information at the bottom of the page) which provides information on the average minimum winter temperature in your location, by zip code.
Chill Hours
Many plants native to locations that have cold winters have a Chill Hour requirement to ensure uniform waking up of flower and leaf buds in the spring. The chill hour requirement of plants varies by species, by cultivar, and sometimes by the level of dormancy achieved.
Where to Plant Your Tree
Apple trees need to be planted where they receive at least 8 hours of direct sunlight 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 2 times the diameter of the needed planting hole and up to a foot deep. A 2-4” 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 and Mini-Dwarf apple trees are the best candidates for growing an apple tree in a container. The variety “Queen Cox” is one of the best because it is self-fertile, so if you are only going to plant one apple tree in a pot, this is the one to do!
To grow an apple tree in a pot you need a final container size of at least 25 gallons. Trees will grow larger in a larger container, but make sure you have the ability and tools to move the pots 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.
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 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 be 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 1-2 inches 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 instance 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. In 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 overwinter in buds are shoot tips. Prune out affect shoots and thin to maintain good air circulation.
Fireblight
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
Coddling 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, crapabble) 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/Cork Spot
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 only trained large dogs patrolling the perimeter are effective. Some have had success with the product “Deerchaser.”
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
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.
FRUITS
Aphid
Symptoms
1/32 to 1/8” long pear shaped insects that multiply rapidly, espe- cially 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.
Ant
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 orangish 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.