Chapter 10: Pruning Nut Trees
One of the nice things about nut trees is they grow easily from seed. If you plant a seed or buy a seedling from a nursery, expect to wait six to 12 years for it to bear fruit. Grafted nut trees take less time, and the nuts tend to be larger and easier to crack. In addition, grafted seedlings will bear nuts earlier than non-grafted ones and will produce a heavier crop than trees grown from seeds.
If you plant a seedling lightly branched, prune all the branches back to the first bud from the end, and cut the top back to the second bud from the top of the tree. You can also cut the branches back to the main stem and leave the top of the tree intact. If your whip has no branches, remove a third of the total length of the tree to just above a bud.
When nut trees grow wildly in the forest, they tend to lose their lower branches as the tree grows toward the sun. If your whip is a large, growing nut tree, you will want to train it to grow with a central leader. Prune all branches that will weaken your tree, such as long, heavy, horizontal branches that will put a strain on your young tree and eventually split off. Also, remove any branches rubbing other limbs or forming crotches less than 45-degree angles.
When your nut tree matures, continue to remove dead, diseased, or damaged branches, as well as limbs with heavy nut loads on weak crotches.
Pecan Trees
Pecan trees are native to the southern and southwestern parts of the United States. They are deciduous trees related to the hickory and can grow 66 to 130 feet tall. If you plant a pecan, make sure you have the room for it because their trunks can grow to 6 feet in diameter, and while each tree can grow both male and female flowers, they need another variety to pollinate. They can also live up to 300 years.
You should train young pecan trees to grow with a central leader and should prune them when the tree is dormant, in late winter, and past its fruiting time, which is October. You can grow them with a modified central leader, but a central leader is preferred because it makes for a stronger tree to hold the heavy nuts. If your tree has more than one leader, choose one, and remove the other. Upon planting your pecan tree, cut back the leader to half the size of the tree, usually about 36 to 42 inches tall.
Wait until the tree’s first dormant period in late winter, and tip prune the leader. Next, decide which branches will be the main ones, tip prune those, and remove the others. Choose carefully, since pecan trees have longevity and your choices will be apparent over decades. It is best to keep those branches that form wide angles with the central leader. In the first few years, tip prune the leader and side branches to shape your tree. You should also remove a few of its bottom branches each year so that over time your tree will eventually have a 6- to 8-foot, branch-free lower trunk. It should take about four to five years to completely shape your pecan tree. Other than occasionally removing dead, diseased, or damaged branches, as well as branches rubbing together or growing crooked — which you can remove any time of the year — your pecan tree will need little pruning during its lifetime.
Walnut Trees
The walnut tree originated in Persia (now Iran), where it made its way to England and then to the colonies. Walnut trees produce both male and female flowers and do best in a continuously warm climate. The male flowers grow off year-old wood, while the females form on new wood. They are drought resistant and are low-maintenance, since a mature walnut only requires occasional pruning.
When planting a young walnut tree, plant it 30 to 40 feet from other trees because walnut trees can grow to 60 feet tall and can live up to 300 years. You will want to plant your tree in spring, after the last frost. Choose a site that receives full sun and has well-drained soil. You can train walnut trees with an open center, central leader, or modified central leader form, but they will grow stronger and larger when formed with a central leader or modified central leader because the terminal bud is easily damaged by weather when the tree is young, which can result in an overgrowth of sprouts that can eventually turn your walnut tree into a bush. You will need to pinch and snip these sprouts continuously in your tree’s early years to keep it with one main trunk. Also, upon first planting, cut your leader stem back about a third. Choose the tree’s strongest branches as the scaffold branches, and remove the rest.
During the first few years, prune the scaffolding branches back by removing the tips, and prune off branches crossing or rubbing against each other, as well as any damaged branches. You will also need to remove suckers that are prone to grow at the root base. You also might want to stake your young tree, since nurseries sell most walnut trees grafted, making the young wood brittle and breakable at the graft.
In most trees, you would want to prune branches that have crotches at less than a 45-degree angle. But with walnut trees, there is less of a risk of crotched branches weakening the tree’s health because this tree is made of hardy wood. In fact, many people grow walnut trees for their wood rather than for their nuts. As your tree grows, you will want to remove any branches growing downward or any limbs that droop and, therefore, might break off because of a heavy load of nuts. Since walnut trees are great shade trees, prune lower branches so you have a space you can walk on underneath the tree about 6 to 8 feet.
Your walnut tree can start producing nuts when it is 6 years old, but it is not considered mature until 10 years old. Once your tree matures and starts producing nuts, prune it in early fall after you pick the nuts. Do not prune in spring because walnut trees tend to bleed badly then. You will need to prune your mature walnut tree annually to stimulate growth and to prevent the interior of the crown from becoming shaded, restricting nut production. Remove dead, diseased, or damaged branches or limbs crossing or rubbing against each other. You will also want to remove lower branches over time during the fall so you eventually have 9 feet of branchless trunk that will enable you to reap the full benefits of this shade tree.
Chestnut Trees
Chestnut trees are deciduous hardwood trees that can reach 100 to 130 feet high and up to 10 feet in diameter. The northeastern part of the United States once contained bountiful American chestnut trees, but they were almost entirely wiped out in the early 1900s because of a chestnut blight, which is a fungal disease brought into the country on Asian chestnut tree imports. Today’s variety is crossbred with imported chestnut trees to make them blight resistant, although there is a movement to restore the American chestnut tree across the United States. Chestnut trees bear three nuts in each green burr in late summer and early fall.
Chestnut trees can grow in Zones 4 through 8, but they do best in areas with hot summers. They grow rapidly and make great shade trees, but do not plant your tree near a patio of heavy foot traffic because they produce a large crop of nuts that fall to the ground. You also need to make sure you have plenty of space because chestnut trees are cross-pollinators so you will need to plant more than one tree in order to produce nuts. You need to plant your trees at least 35 feet apart. You also need to plant your tree in fast-draining clay soil.
Your chestnut tree will need a strong central leader with an equal number of branches on each side so train your young tree with a single trunk. Remove any lower branches below 5 feet on the trunk, as well as any suckers growing straight up or down. Lower branches and suckers will zap the tree of the energy it needs to grow tall and straight.
The nice part about a chestnut tree is that as it matures, it should only need minimal pruning. Prune only in the fall, and do not prune from April to July, when the tree will bleed heavily. Do not prune the top more than a third to a fourth back in any one year, or you could stunt or kill your tree, and do not prune any branches growing directly off the trunk, unless diseased or dead.
Chestnut trees bear flowers and nuts on new shoots in the second to tenth year. Encourage nut production by removing branches that cross or rub against each other, as well as any diseased or dead wood. Since the wood is brittle, it is also important to prune back long branches in order to prevent breakage that can open the tree to disease or insect infestation. Use a net to catch the nuts, since chestnut tree nuts are not picked; rather, the tree drops them to the ground. As your chestnut tree ages, you will discover it produces more nuts with every passing year.
Hazelnut Trees
Hazelnut trees, also known as filberts, are found all over North America, especially in Oregon and Washington, although Turkey is the world’s largest producer. You can grow them as either trees or shrubs, although they are usually grown more as bushes rather than trees. If you grow your plant as a tree, the best form to train it in is with an open center. It adds a tasty addition to your garden, especially if space is limited, because hazelnut trees stay small at around 12 feet tall and 5 to 10 feet wide. In addition, you will need to plant more than one tree because hazelnuts need cross-pollination to bear nuts. If you have a grafted tree, you will need to stay on top of the suckers that will grow around the root base.
Hazelnut trees and bushes produce nuts in the fourth year. Mature hazelnut trees need little pruning, but it is important to prune in late fall, winter, or early spring when it is dormant. Prune back about a third of the branches, enough to stimulate the new growth needed for the following year’s crop and also to keep your tree in shape. Remove old or dead branches, as well as those that cross or rub against each other or those damaged during the winter. You also might want to thin the top of the tree so the crop receives adequate air and light.
If your hazelnut is a bush, prune it to only five or six main stems. This will keep your shrub from getting too wide or turning into a thicket. In the 12th year, cut your bush to the ground in spring. You will not get any nuts that year, but your bush will come back healthier and hardier.
Let the nuts from your tree or bush fall to the ground rather than trying to pick them. Use a net to catch them because your tree or bush will produce a bounty of nuts.