Apples

Growing apples is highly rewarding, but don’t try starting one from seed.

These particular fruit trees are what is known as “extreme heterozygotes”, which means the offspring are very unlike the parent plants. Planting seeds from a Red Delicious apple, for example, will not produce apples that look or taste like a Red Delicious. This is why most modern apple trees are propagated from cuttings which are grafted onto sturdy root stock. 


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Did you know that apples are related to roses?

Photo of Fuji apples by Aomorikuma (Wikipedia)

Apple history

Apples (Malus pumila, aka Malus domestica) have a rich and varied history. They hold a place in nearly every culture and religion, being one of humankind’s earliest attempt at tree cultivation. Wild apple trees (Malus sieversii), however, bear little resemblance to their domesticated progeny. Wild apple trees, still found in central Asia, can grow up 40 feet in height and the fruit is smaller and more tart than most people find palatable. Most of the apples you see in the grocery store are crosses between Malus pumila and crab apples. To date, there are over 7,500 apple cultivars with various traits of skin color, texture, disease and pest resistance, juiciness, storage ability, and more. In 2010, the entire apple genome was mapped, with over 57,000 genes identified. (Humans are estimated to have up to 25,000 genes - kind of makes you wonder, doesn’t it?)


Bare root apples

The best way to start growing apples is with bare root stock. When selecting your root stock, keep in mind that some apple varieties require cross-pollination, while others are self-pollinating. If you only have room for one tree, you will want to be sure to select a self-pollinating variety or all you will get is summer shade. Bare root stock should be planted in January, February, or March in the Bay Area. According to UC Division of Agricultural and Natural Resources (UCANR) and local Master Gardener trials, and depending on your tastes and microclimate, there are many apple varieties that perform well in Santa Clara Valley. Before you buy, however, you may want to conduct a soil test with a reputable lab. This is an excellent investment in a tree that will probably live and produce fruit for the next 100 years or so. Also, consider the size of your mature tree - it is far easier to pick apples and care for your tree if it is a dwarf or semi-dwarf variety.


Chill hours

Most red varieties will need more chilling hours than they will get in the Bay Area. Red apples generally need 1200 to 1500 chill hours to fully develop their color and flavor, while some microclimates in San Jose only receive 400 chill hours a year, on average. Also, our local fog can cause more russetting. Russetting is when the apple’s skin turns brown and rough.


How to grow apples

Apples grow best in well-drained, nutrient rich soil with full sunlight. Apple trees need some space for good air flow. Full-sized trees will need a 15 to 20-foot circle of space, while dwarf varieties need only 10. Dwarf apple trees do tend to over-produce, breaking branches, so you may need to do more pruning or provide supports. Once your bare root tree arrives, dig a hole that is twice the diameter of the spread out roots and about 2 feet deep. You should remove any grass or weeds that are growing within two feet of this circle. Remove any dead, damaged, or diseased roots and then soak the root stock in a bucket of water for a couple of hours (overnight, if the roots are really dried out). Mix some aged compost in with soil from the hole and spread it out in the bottom of the hole. Be sure to not leave smooth edges in the hole. Our heavy clay can create an impenetrable barrier to young roots. You can help your apple tree get a better start by roughing up and scoring the edges of the planting hole. Place the tree in the hole, making sure that the graft union (the place where the root stock joined the scion) is at least 2 inches above soil level, to avoid crown rot and other fungal diseases. Firmly press the soil down to eliminate big air pockets and give it a good drink of water. You can also grow dwarf apple trees in containers!


Seasonal apple care:

• Winter apple tree care includes pruning 15 to 20% of last year’s growth, to allow more light into the middle of the tree and to remove dead or diseased branches, and spraying dormant oil to control San Jose scale, and aphid and mite eggs.

• In spring, apple trees should be treated with some sort of fungicide that will help prevent powdery mildew and apple scab. These treatments should occur when twig tips first green, when buds are pink, and then every 10 days until the rainy season ends. A month or two after the tree is covered with blooms, fruit should be thinned to one piece of fruit every 6 inches, for better growth and flavor. If apple maggots or codling moth have been a problem in previous years, bagging the fruit or coating it with kaolin clay are organic methods of protecting your valuable crop. Before you start irrigating a mature apple tree in spring, be sure to feed it with the equivalent of two pounds of urea or 40 pounds of aged manure.

• Summer chores include feeding young trees 20 pounds of aged manure or 8 ounces of urea every month and watering it in. (If you use drip emitters, be sure you do not use more than 1 ounce of urea per emitter per application.) Spray for codling moth, May through September, and monitor for aphids and mites. Because our summers get so hot, trees should be irrigated every 2 to 3 weeks. If drip emitters are used, water daily. Some varieties will reach maturity in July. As you pick ripe apples, be sure to look for and remove any mummies you come across. You may need to do some pruning, to control overall size.

• Fall is harvest time! After harvesting, fertilize mature trees the same way you did in summer. Remove all leaves from around the tree and compost them. This will help prevent apple scab. Mulching will reduce weeds, stabilize temperatures, and provide slow release of nutrients.

Apple pests and diseases

There are very few pests or diseases that will actually kill an apple tree, but it has many attackers. The use of sticky barriers around the trunk will halt some, such as ants, slugs and snails, and Fuller rose beetles, but most most apple problems are carried on the wind. Stem blight, crown gall, leaf spot, powdery mildew, fireblight, and other bacterial blights are common diseases. Cedar apple rust can also occur if apples are grown near Eastern red cedar trees. Also, apples share a susceptibility to bacteria blast with lilacs and stone fruits. Common pests include codling moths, apple maggots, San Jose scale, redhumped caterpillars, armyworms, and Eriophyid mites.


Find a spot in your landscape for one of these beauties, because plucking an apple from your very own tree and taking a bite, well, it's just one of life's finer experiences. And we all want to keep that doctor away!