Archive for the pruning tag

Encouraging grapevines to produce fruit

March 30, 2016 • Leave a Comment

When is the best time to trim back my grapevines? And how far can I prune them back? They are on an arbor and have grown very thick. They did not produce much fruit last year.

The best time to trim back any grapevine is roughly March to early April. The object is to minimize sap bleeding from pruning cuts. Sap is what feeds the new growth that will produce your fruit. Grapes are borne on new growth that arises from last year’s wood. Once the sap begins to run, the bleeding from pruning cuts is difficult to stop.
It appears your vines need thinning, as evidenced by their thick growth and lack of fruit. Grapevines are very long-lived. The permanent stems, or “rods,” can become very thick and aesthetically gnarled. However, they can still produce strong new fruit-bearing shoots. The key is to restrict the vegetative growth so that fewer but finer bunches of grapes are produced.

Depending on the number of permanent stems on your arbor, remove much of the extended vine growth to leave two or three strong stems per permanent rod. Then cut those stems down to one or two strong outward-facing bud nodes. From these swollen bud nodes will come the strong shoots that will produce fruit. When cutting to buds, always cut beyond the swollen node to prevent structural damage to the stem. Once new growth begins, watch for excessively long young shoots. Prune these green vegetative shoots away to just above their node.

An ongoing exercise throughout the growing season, this pruning will concentrate sap into the main fruiting stems and allow air to circulate and more sunlight to reach the fruiting vines. Without vigilance, you get the indiscriminate tangle currently occupying your arbor.

Spring is the time to stop pruning oak trees

May 9, 2015 • Leave a Comment

MSU Extension:

Fresh pruning wounds of oak trees attract beetles that spread oak wilt. It is critical to not prune oaks from April 15-July 15 in Michigan.

Oak wilt is an aggressive disease that affects many species of oak (Quercus spp.). It is one of the most serious tree diseases in the eastern United States, killing thousands of oaks each year in forests, woodlots and home landscapes. Oaks in the red oak group, distinguished by oak leaves with pointy lobes (Photo 1), are much more susceptible to the disease than white oaks, distinguished by oak leaves with rounded lobes. However, all oaks can be affected.

Read the rest of the article…

Pruning lavender plants

April 11, 2015 • 2 Comments

How much do you trim lavender bushes? Mine are getting rather leggy and sprawling. When is the best time to prune them?

Let’s assume these are English lavender plants (Lavendula angustifolia), since these are hardy and the most popular in our area. There are many varieties of English lavender, but all have the same basic care. There may be several reasons why your lavender plants are getting leggy and sprawling, including pruning, water, light, and soil.

Pruning is essential for lavender. Pruning is not the same as harvesting. When flowers are harvested, typically not much of the plant is removed. Growers prune plants twice a year: very early spring (April) and after they bloom. Lavender will become leggy and flower production will decrease significantly if it isn’t pruned quite hard. Prune down to three nodes on the new growth above the old wood, which looks gray and isn’t flexible. The plant is usually trimmed to a dome shape to let in lots of light and to help the air circulate. April is a good time to do this. Then do another trim in late summer to early fall. If you happen to prune at the wrong time, don’t worry, the blooms will be back even stronger next year.

Another factor that contributes to a leggy, sprawling plant is overhead watering, or too much water. Lavenders are very drought tolerant, especially after they are established. Watering should only occur as a supplement for hot, dry weather and they should not be placed where sprinklers water daily. In a typical Michigan summer (no droughts or periods of high temperatures), no watering at all may be needed. Light, as in full sun, is essential. Picture the open fields of lavender in Provence, France. Lavender doesn’t need a special soil, so long as it is very well-drained, even sandy. Very rich, clay or damp soil is not recommended.

Web Extra: Pruning to make great evergreens

October 31, 2013 • Leave a Comment

To read the full article by Janet Macunovich on pruning evergreens, pick up a copy of the Nov/Dec, 2013 issue of Michigan Gardener in stores or find it in our digital edition.

Captions by Janet Macunovich / Photos by Steven Nikkila

Even a tiny branch (circled) has great potential. Once clipping changes its position from shaded interior to sunny outer edge, this wimpy twig can become a husky, densely feathered leader.

Evergreen pruning can be done at any time. I can even thin at one time, and cut back overall at a different time. I take advantage of that in winter when we need long branches for decorations. Look at all the great cuttings I've gathered just from thinning this boxwood (left) and these hollies (right). — Evergreen pruning can be done at any time. I can even thin at one time, and cut back overall at a different time. I take advantage of that in winter when we need long branches for decorations. Look at all the great cuttings I’ve gathered just from thinning this boxwood (left) and these hollies (right).

Work with the natural shape of the plant and you can do all the cutting at once, using pruners. Most stems are clipped by one year's growth. The thickest are cut by two years'. These shrubs were a matched set five minutes ago. They will be again in five more minutes once I've clipped the one on the left. — Work with the natural shape of the plant and you can do all the cutting at once, using pruners. Most stems are clipped by one year’s growth. The thickest are cut by two years’. These shrubs were a matched set five minutes ago. They will be again in five more minutes once I’ve clipped the one on the left.

If a shrub has become too big (photo 1), I wait until early spring to cut and thin. For instance, I cut and thinned these boxwoods shortly after budbreak (photo 2). At other times all this previously sheltered wood and foliage would have been suddenly exposed to summer heat or wintry cold. Such quick changes can kill leaves and make wood die back even further than it was cut. Recovery was well underway in August of that same year (photo 3).

When is the best time to prune trees and shrubs?

May 28, 2011 •

by Steve Turner

I am often asked when is the best time and what should be pruned. The ideal time is when the tree is dormant, which is late fall to early spring. Since the tree is not active, the removal of limbs will be less stressful to the plant. It is also easier to see the structure of the tree without its leaves to better find problem areas like rubbing branches, weak crotches, cracked or broken limbs and competing leader branches. The tree will have more time to seal the wounds before the growing season starts and there will be less sap running from the wounds. Also, insect and disease organisms are not active at this time, so it reduces the risk of infection or pest infestation, which is why birches and American elms should only be pruned in the winter. The worst time to prune trees is late spring and early summer when their leaves are expanding and the tree is putting its energy toward growth.

A common myth is that large, mature trees can tolerate more pruning than small trees. In fact, the opposite is true. Only the outside inch or two of a tree is alive; the rest is made up of dead cells whose main function is to support the tree. That’s why a tree can be hollow but still be perfectly healthy. If you compare the percentage of live cells to dead cells between a small tree and mature tree, the difference is huge. A young tree might be made up of 90 to 100 percent live cells, while an old, mature tree might only have 10 percent or less. As you can imagine, the younger tree has a better chance to adjust to change.

A good rule for mature trees is that less is better. Try to avoid removing large limbs over 6 inches in diameter because it will be difficult for the tree to close the wound before decay sets in. Other options are cabling or thinning these large limbs as opposed to removing them. Good maintenance items for mature trees are removing deadwood and hazard limbs and thinning for weight reduction when necessary.

Young trees up to 8 to 12 inches in diameter need to be pruned properly for structure while they are still young to avoid the need to remove large limbs in the future. When pruning trees, keep in mind that the leaves produce the energy for the plant and that removing too much leaf surface from a tree or limb will starve the plant, causing die back or heavy sucker growth from that part of the tree.

“Topping” trees destroys them. They will never grow back to their natural shape and every branch that grows out of that wound area will be an accident waiting to happen. As the new limbs grow bigger and the rot in the wound increases, the branch will eventually break. A topped tree soon becomes a maintenance headache, with constant storm damage due to the weak branch attachment. If a tree is too large for its location, consider having it removed and replanted with a smaller species rather than topping it.

It is important to know what a tree’s natural shape will be when it matures before you prune it. For example, I see many weeping cherries that are pruned into a ball shape because all of the upright limbs were removed as they grew out of the top. If allowed to continue growing, these limbs would have eventually bent back down, creating the weeping effect that gives the tree its unique look. So it pays to do a little homework and find out what the tree’s natural shape is and help it reach its full potential. Not all ornamental trees need to be pruned into the traditional lollipop shape!

When it comes to shrubs, prune flowering shrubs soon after they are done blooming. Non-flowering shrubs and evergreens can be pruned as necessary to achieve a desired shape. Keep in mind that wider at the bottom is better than narrow — if you allow more sun to reach the bottom of the shrub, the plant won’t thin out as much. Avoid heavy, late summer pruning; too much pruning at this time will encourage new growth that may not harden off in time for winter. For those plants that don’t tolerate shearing well, like red or green twig dogwoods, it is best to prune them back to the ground when they become too large or sparse, and let them start over again by growing new limbs from the base.

Steve Turner, Certified Arborist, is from Arboricultural Services in Fenton, MI.

How to prune Caryopteris

February 22, 2010 •

Is Caryopteris a perennial or a shrub? It doesn’t seen to die back all the way to the ground, but seems like it does have some deadwood on it each spring. I never know how and when to prune it.

Caryopteris, commonly known as bluebeard spirea or blue-mist spirea, is really a woody shrub in more southern areas of the country. Here in Michigan we should consider it a woody perennial since the amount of spring dieback will vary with the severity of the previous winter. Many other shrubs commonly grown in our area can be treated in a similar manner. These include: butterfly bush (Buddleia), beautyberry (Callicarpa), bushclover (Lespedeza) and Hypericum.

Spring pruning can be approached in one of three ways:

Prune all of the stems down to 6 to 8 inches in early to mid-April. This keeps your shrubs approximately the same size each year since they begin their growth from the same starting point.
Wait until May when buds begin to swell and growth emerges. Any wood that remains inactive can be pruned off at this time. Scratching the bark with your thumbnail will also reveal where green living wood merges into brown tissues where dieback has occurred.
An intermediate approach (especially useful after mild winters) is to prune the plant back in April by about one-third to help the shape and overall neatness. Wait until growth emerges later in May, then prune off any winter dieback that remains. Methods 2 and 3 will allow the shrub to gain additional size each year as long as winter conditions allow.

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