Last week in our series of urban agriculture articles I wrote about selecting, buying, and growing fruit trees, but the work isn’t finished when your fruit tree gets planted.
Regular training and pruning are important steps in growing fruit trees and can impact fruit production from one year to the next. Left without thinning, training, and pruning, many fruit trees will begin alternate bearing, also known as biennial bearing, which means you will only get a good crop of fruit every other year. In one year fruit production will be really heavy and the next there may be little or no fruit at all.
Apple trees are most notorious for alternate bearing, but other fruit trees such as pomegranates, olives, avocados, and pears can also start alternate bearing if not properly thinned.
To get the best fruit crop and larger fruit, you must thin the fruit on fruit trees so they do not overbear. The act of thinning the fruit accomplishes four tasks:
- Allows the remaining fruit more space to grow larger and attain better flavor.
- Increases the chance of annual crops and reduces biennial bearing.
- Improves the strength of the tree, reducing the chance of branches breaking from heavy fruit.
- Enables you to battle insects and disease by destroying injured, smaller fruit and improving air circulation.
Thinning can be done by pruning flower buds, but thinning generally occurs once the fruit is set, a time that makes it easy to determine which fruit appear larger and healthier. Peaches are thinned when they grow to the size of your thumb. This “rule of thumb” works for most other fruit trees as well. In general, people tend to not thin enough. You should err on the side of thinning too much.
Training Fruit Trees and Fruit Tree Forms
Fruit trees can be grown in a variety of different forms, but some are more popular than others. Bush, bush-standard, and standard forms are popular with novice fruit tree growers because they are the most tree-like and take the least amount of pruning and maintenance.
A pyramid shape is preferred for almost all fruit trees except peach trees in northern states. Plums do especially well in a pyramid shape because it is suits their fruiting habit, and the longer, broader lower branches allow ripening plums to receive plenty of sunlight.
Peach trees and dwarf pear trees should be trained to have the lowest branches starting at 12 to 24 inches above the ground. Sweet cherry and standard pear trees should have lower branches, no more than 30 inches above the ground, with apples, sour cherries, and plums a bit higher.
If you will be using a trellis for training fruit trees against a wall, one of the cordon, double cordon, multiple cordon, fan, palmette, stepover, or espalier fruit tree forms may be more appropriate. Using a trellis for training fruit trees helps when space is limited, but training a fruit tree on a trellis also increases the amount of maintenance and pruning needed to keep the tree in its precise shape.
Pruning Fruit Trees
You should prune fruit trees to heights according to tree type, though low heads for most fruit trees are desirable for making harvesting and pruning more accessible. Pruning helps to both direct the growth and structure of the tree and stimulate growth.
Most pome fruit trees, such as apples, pears, and quince, should be pruned in late winter or early spring, but this can differ depending on fruit type and climate. For example, in some areas stone fruit trees should be pruned in the summer.
When pruning new, young growth, you should pinch or cut back to a leaf or its nearest point of origin. Hand pruners can be used to cut branches up to the size of an index finger. For branches larger than 1 inch, use a pruning saw or loppers.
There’s one important note that most people don’t realize about pruning. Pruning stimulates growth. Therefore, it’s important to remember this rule: Prune weak growth hard and strong growth lightly.
You should be careful not to over-prune or the fruit trees will limit fruit-bearing in favor of more wood production.
Tips for Growing Fruit Trees
Each fruit tree will have particular needs. When growing the popular fruit trees, follow these tips:
- Apple Trees: Apple trees thrive in a wide variety of landscape conditions. They grow best in a strong, sandy loam soil. Most varieties should be planted 35 to 40 feet apart.
- Sweet Cherries: Sweet Cherries (hearts, bigarreaus and dukes) boast larger, taller trees than sour cherries (Prunus cerasus hybrids and pie cherries). Sweet cherries prove challenging and need attention to spraying and picking the fruit when dry to reduce loss.
- Sour Cherries: Sour cherries usually ripen later and thrive on clay loam soils. They should be planted 18 by 18 feet apart in well-prepared, under-drained soil. Trees should be trimmed slightly every year and the heads should be low and busy.
- Peach Trees: Peach trees thrive in warmer climates where they are protected from frost, but can also grow in other areas. Peach trees are short lived, so you should expect only three or four crops starting in the third year after planting.
As you can see, growing fruit trees requires ongoing thinning, training, and pruning at least on a yearly basis. If you’re training fruit trees on a trellis as an espalier, pruning and maintenance increases to several times per year. Fruit trees are not as much responsibility as raising a new puppy, but in order to get a good harvest, you need to commit to good pruning and maintenance.