An Apple a Day
By Joe Michalek, Sonoma County Master Gardener
A little bit about apple trees
As the old saying goes, “An apple a day keeps the doctor away”. This is more than just a fable from good old Ben Franklin. Here are some reasons why apples are so good for you: they are high in Vitamin C, which aids in the healing of wounds and reduces the incidence of bruises and bleeding gums; they are rich in flavonoids, which help prevent heart disease, they contain antioxidants and, eaten fresh, they are low in calories. They also contain phenols which help lower the bad cholesterol and increase the good cholesterol. Finally, they come in many colors and flavors to suit the palate.
Now that one can appreciate the good properties of this wonderful and beneficial fruit, how does one go about deciding which variety to plant? In our area we are blessed with many apple growers who will let you sample the ripe varieties available at their ranches. There is a wealth of information which one can obtain from talking to the rancher about the different varieties which do well here. One can learn about the growth habits of a particular variety, how and when to prune that tree. All of that information may be a bit overwhelming at the time you are talking to the grower; however, it will come in handy later when the tree begins to grow in your back yard.
Choosing your apple tree
Apples, like many fruit trees, are best purchased bare root, and local nurseries will have their selections in stock beginning in January. Now is the time to start thinking about what kind of apple tree you’d like to plant, so that you are ready when the trees arrive!
One reason to buy locally is that the trees which are available in our nurseries during the bare root season are all suited to this county, which means that our winter temperatures will be low enough to induce them to produce apples. This measure is called chill factor, and is the total number of hours annually between 32-45 degrees that a plant requires to set fruit. In Sonoma County the chill factor ranges from about 400 - 1100 hours. Also one needs to know if a cross-pollinator is required for the tree to bear. As there are many micro-climates in the County, discuss your chosen variety and proposed planting location with your nursery to ensure that you are making an appropriate selection.
Most fruit trees, like roses, are grafted, which means that growers combine shoots, or scions, of one variety with roots of another. The scion determines the specific variety of apple that the tree will produce, while the rootstock controls the ultimate size of the tree. By mixing and matching various scions and rootstocks, growers can produce dwarf and standard varieties of many different kinds of apple trees. The graft leaves a visible bud union, which is the place where the scion of the specific variety you have chosen was grafted onto an existing rootstock. Look for a small jog at the spot where the roots turn into the trunk. It will be important to note the placement of the bud union when you to plant the tree, so ask the nursery to help you identify the spot when you are purchasing the tree if you are unsure.
Most yards in our county are not that big, so most people want to select a tree that is on a rootstock which will reduce the overall size at maturity. Rootstocks are available which can keep the tree from eight to 14 feet tall, with a canopy also from eight to 14 feet across, based upon the apple variety selected. If there is not a rootstock available that will reduce the tree size of the variety you select, the tree can be kept low and compact by judicious summer pruning. There are many ways to prune apples, but the tree must be pruned every year to keep it a manageable size. To decide if you want to take on this task, check the California Rare Fruit Growers website for a discussion of summer pruning and what it involves: http://crfg.org/tidbits/backyardorchard.html. If it looks like more than you want to take on, make sure to select a variety grafted onto a dwarf rootstock.
Some nurseries promote a multi-grafted tree where there are from three to five different varieties on one trunk. While this may seem like a nice way to have an apple tree that will bear fruit throughout the entire fruiting season, there are drawbacks. The biggest problem is that there is always one graft that will become dominant and out-grow the rest of the grafts on the tree. If one should purchase a tree with many grafts be certain to label each different variety so that one of the grafts is not inadvertently removed during the dormant pruning season.
Now that you know how apple trees are grown and their primary requirements, select your own variety based on your favorite flavor and desired growth habit!
Joe Michalek grows many different kinds of fruit trees in his garden in Santa Rosa. Look for Part II of this series in January, when we’ll discuss how to plant and care for your bare root fruit tree.