Aside from their use in commercial orchards, pomegranates have many uses in the residential landscape and are immensely popular now for use in "edible landscapes," where they can be grown as bushes, hedges, single- or multi-trunk specimen trees, espalier (trained to grow flat against a wall) and in containers. However you train it to grow, you'll have a hummingbird magnet when the trees produce their flowers in spring.
There are many varieties of pomegranate that can range anywhere from a dwarf shrub of 3 feet mature height to a small tree of 20 to 30 feet in height. Make sure to choose a size that fits the space you intend to fill.
In its natural environment, the pomegranate is a shrub and the best method of training is to leave it a multiple-trunk shrub. That being said, pomegranates can be grown as a single- or multi-trunk tree in the warmer sections of the United States. To obtain good fruit, the plant must be pruned on a yearly basis to either a single trunk or the more desirable multiple trunks. Pomegranates have a tendency to sprout numerous suckers even when older so these will have to be removed as they emerge from the base of the tree.
There is a dispute in the commercial pomegranate growing world as to whether a pomegranate should be grown as a single trunk tree or a multiple trunk shrub. In warmer regions, some commercial growers use the single trunk concept and think that it's the best. In most of the rest of the commercial pomegranate growing world, pomegranates are grown as a multiple trunk shrub. To make matters a little more confusing, some of the multiple trunk growers say 3 trunks is best and some say as many as 6 is best. But they all agree that the number of trunks must be limited to a small number, because if you let the plants go they will become a hedge-type plant and you will see little fruit.
That being said, the single-trunk system will work for anyone when more cold-resistant varieties are selected, or when growing less cold-hardy varieties in areas that do not stand any chance of a very hard freeze that will kill the plants back. When growing less cold hardy varieties in the cooler winter areas, multiple trunks are the only way to be somewhat assured of fruit production.
Before you start pruning your pomegranate, you want to decide how it will be used in the landscape or garden. No matter how you intend to use it, pomegranates are pretty in three seasons, you’ll enjoy its shiny leaves and crinkly red-orange flowers in spring, and uniquely shaped rosy-red fruits in summer and fall that are produced on the fruit bearing varieties.
When to prune...
Wether grown as a shrub or tree, pomegranates should not be pruned at all during the first year after propagation to allow the plant to establish itself without any disruptions. The second year, when they are more established, you can start you pruning or training.
All heavy pruning should be done during the dormant/winter season. Light pruning, to open up the plants and remove suckers can be done in the summer, usually in August.
Pruning as a shrub...
When growing pomegranate as a shrub, for best fruit production over the long term, you'll want at least 5 to 6 sprouts/trunks to form the bush. If your newly planted pomegranate has less than this allow a few more suckers/shoots to emerge until there are 5 or 6 and then continue to remove other suckers as they emerge by cutting them off at ground level. You might have to remove suckers several times a year during the growing season to keep your plant to 5 or 6 trunks. If you let it sucker freely it will put all its energy into growing branches and foliage and the result will be less fruit.The suckers can rob so much energy from the rest of the plant that the established trunks can actually die back. This is especially true during the early years of growth. Sometimes a trunk may die back or get injured. If this happens, remove the old trunk and allow a sucker/shoot that is closest to where the lost trunk was and leave it as a replacement.
Training as a tree...
Growing pomegranate as a tree is only suggested for regions that have warmer winters. If you want to train your pomegranate into a tree the process must be started soon after planting and on plants 2 to 3 years old and at least 3 feet in height. If the plant is less than 3 feet tall allow it to grow to this height before starting the training process. To start, you'll need to select 1 to 3 shoots you want to keep that will be the main trunks of your tree. Remove all other shoots by cutting them off at the ground. Because pomegranate suckers profusely from the crown, frequent sucker removal will be necessary to train the plant into a tree form. Sometimes a trunk may die back or get injured. If this happens, remove the old trunk and allow a sucker/shoot that is closest to where the lost trunk was and leave it as a replacement.
Growing as a hedge...
Pomegranates are very useful to create a hedge that can serve as a windbreak or walls to separate garden spaces in the landscape. Very little pruning will be necessary when growing them as a hedge. How far you space the plants will depend on the variety and it's average mature width. I suggest spacing them at a distance of 75 percent of their mature width. For example, if a variety typically grows to 10 feet wide I would space the plants about 7 to 8 feet apart. The shrubs will spread their branches, and suckers will also grow between the original plantings, to form a hedge. Basically, if you are growing pomegranate as a hedge then let it sucker all it will, and it will.
Pruning in containers...
Use a container to place your pomegranate anywhere on your hardscape or in your garden. Train it as a single-trunk or as a small shrub using the same pruning techniques as you would when growing them in the ground.
Pomegranates bear on both older wood (2-3 years old and older) as well as the current season’s growth. It is good during early pruning, before the plants bloom and while they are still dormant (March), to remove about one-half of the branches and shorten the remaining branches a little so they will not flower. You want the fruit to be on the older wood. When pruning for best production, when your plant gets older, remember this: the more light and air the blooms get the better the fruit set and fruit production will be. So when pruning the growth from the older 5-6 trunks, open up the middle and remove overlapping secondary limbs. Most of the fruit will be set on the outside of the shrub on new growth spurs from the older trunks. But keep in mind that pruning too heavy can and often will reduce yields.
On older pomegranates, commercial growers top their plants at about 10 feet in order to make picking easier. Topping does not seem to reduce production and is recommended in orchards because it does make it a lot easier to pick the fruit and to apply any sprays for pests and diseases that might occur.