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KEEP SPRING FLOWERING SHRUBS BLOOMING WITH PRUNING

written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
published – MAY16, 2014

KEEP SPRING FLOWERING SHRUBS BLOOMING WITH PRUNING

Last weekend I took advantage of the nice weather to prune my forsythia that was seriously crowding nearby plants. I hadn’t pruned it much for the last two years and it was becoming unruly. It put on a beautiful show of blooms this spring, but I knew that if I didn’t get in there and remove some of the old wood it probably would not have as many flowers next year.

My approach was to go in and remove one-third to one-fourth of the older (thickest stems with side shoots) stems down to the ground. A healthy forsythia is a vigorous shrub that sends up new stems each year that bloom the following spring. Removal of the oldest stems should be done right after flowering because the flower buds for next spring are formed on the new wood by early summer. Pruning later in the season or in winter will reduce the potential flower display next spring.

Occasionally, one or more forsythia stems grow rather long, giving the shrub a rangy, wild appearance. If not an older stem that should be removed, I cut the stem back to a side branch to shorten it.

A weigela was one of the plants being crowded by the forsythia. I planted it in early summer two years ago and initially it benefitted from the shade the forsythia provided, but now it needs more light. I also have two mature weigela shrubs elsewhere in my landscape.

One of these weigelas is ‘Wine and Roses’ with dark burgundy leaves and dark pink flowers. It has prospered in its spot but now it has become a bit bedraggled and there are a number of dead twigs and branches throughout. Since weigelas are prone to winter dieback, this may have been caused by the sudden cold snap last fall. The dieback could also be related to the increasing amount of shade provided by two trees on that side of the yard. Weigelas do best in full sun and will become straggly if located in shade or crowded by other plants.

Perhaps I should just remove it and plant a more shade tolerant shrub, but I think I will see if I can revitalize it first. As soon as it is done blooming, I am going to prune out the thickest, oldest stems along with any of the dead branches and twigs. To shape it up a bit, I plan to selectively prune back any overly long stems to a side branch, being sure not to remove more than one-third of the stem.

Most other multi-stemmed spring-flowering deciduous shrubs are also pruned right after flowering. This is because they too flower on wood produced the previous growing season. These shrubs include forsythia, weigela, lilac, viburnum, honeysuckle, mock orange, Nanking cherry, flowering quince, white-flowered spireas, beautybush, and deutzia. Like forsythia and weigela, one-fourth to one-third of the oldest wood should be removed back to the ground each year.

As part of your pruning tasks, you should also “deadhead” or snip off the spent flowers or seed-heads from the stems you don’t remove. This will give the shrub a tidier appearance and allow its energy to go into plant growth rather than seed development.

It really does not take much time or effort to keep spring flowering shrubs looking their best. Give it a try. Sometime soon we can chat about pruning summer flowering shrubs.

Published: 5/16/2014 11:48 AM

STOP AND GO, GO, GO FOR GARDENERS THIS SPRING

written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Go. Go. Go. Stop. The very mild spring weather that we have experienced over the last month has plants and gardeners getting ready to go, but some recent cold nights may be putting the breaks on a bit. I’m always wary of early warm spring weather, because weather has a way of changing very abruptly. However, the tenuous forecast for the remainder of the month indicates daytime temperatures in the 60 degree range and nighttime lows above freezing. Based on this forecast, gardeners can get going.

Crabgrass Preventer or Pre-emergent Herbicide: The time to apply these “preventer” type materials is before crabgrass germinates. When crabgrass germinates is dependent upon the temperature of the top inch of soil. Germination occurs when the daytime and nighttime soil temperature reaches 55 to 60 degrees and stays there for about a week.

We often tell gardeners to wait until area Forsythia is in bloom for several weeks before applying a preventer material. However, this bright yellow flowering shrub is what’s called a phenological indicator. It blooms when soil temperatures are approaching that 60 degree range. An inexpensive soil thermometer is a more accurate way to determine if it’s “time”.

So why do we dither so much over when it’s time to apply “crabgrass preventers” every spring? University research indicates that crabgrass may start germinating when the soil warms up to 60 degrees, but it can continue to germinate over the next 12 weeks. If you apply your preventer material too early, it may dissipate before all the crabgrass germinates later in the summer.

Forsythia is also an indicator that it’s time to prune your roses. Local Tri-City Rosarians recommend pruning your roses when Forsythia is in bloom. Now is the time. As you prune, you may find that last December’s severe cold spell caused some injury to your roses. Prune canes back to where you find white centers. Remove portions of canes where the centers are brown, tan or beige.

It’s warming up fast, so if you haven’t planted your early cool season crops, you’d better get going. Gardeners often like to plant their peas on St. Patrick’s Day. Peas will germinate as soon as the daytime temperature reaches 45 degrees, but grow best when temperatures are between 50 and 60 degrees. If you haven’t planted your peas, lettuce, and cool season spinach, you should. Also, get ready to plant your broccoli, cabbage, cauliflower, carrots and beets soon.

Now is also the time to cut back your ornamental grasses that have died back to the ground over the winter. Cut the grasses back to about 4 to 6 inches from the ground. Some of the cool season grasses have already started to grow, so be careful not to cut back into new green growth. Start by tying all the stems in the clump together using rope or a bungee cord. Use a hedge trimmer or small chain saw to cut across a clump of tough- stemmed grasses. Soft or fine stemmed grasses can be cut with a serrated knife or hand sickle. Clean up evergreen grasses, by gently combing the grass with your fingers using a gloved hand.

So for now it’s go, go, go, unless it snows.

Published: 3/13/2010 11:23 AM

FORSYTHIA ANNOUNCE SPRING’S ARRIVAL

written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Now that fall has arrived and the leaves are falling from the trees, my thoughts turn to next spring. Anticipating the gray days of winter, I’m already anxious for the color of spring. There will be the cheerful traditional harbingers of spring, especially the brightly colored crocus and the early daffodils, but elsewhere in the garden the forsythia can serve as a shrubby herald of the new growing season. This shrub with its bright yellow flowers is the first shrub to bring a mass of color to the landscape. It’s abundant production of yellow flowers along its stems shout out the arrival of spring.

As soon as the weather starts to warm up in late winter, forsythia blooms start to emerge. The star-shaped, bell-like flowers are produced in clusters along the one-year old stems. All cultivars have yellow flowers but the yellow varies from gold to pale yellow, depending on the cultivar. The flowers will last for several weeks unless killed by hard frost. The green leaves then emerge after the flowers disappear.

I classify forsythia as a “grandma” shrub. It’s the type of shrub used in the “old days” for adding color to the landscape and hiding the tall foundations of homes. The common border forsythia grows 8 to 10 feet tall and 10 to 12 feet wide. It’s a very unkempt shrub with some upright canes along with many weeping or drooping canes. It’s wild habit is somewhat charming when in bloom, but downright unruly later in the season.

Border forsythia (Forsythia x intermedia) is a hybrid that is a cross of weeping forsythia (Forsythia suspensa var. sieboldii) and green-stem forsythia (Forsythia viridissima). Discovered in 1878, it had a superior form that was bushier and had greater flower production than either of the parents. Most of the forsythias available at nurseries and garden centers are cultivated varieties (cultivars) of the border forsythia.

There are a number of forsythia cultivars available to home gardeners with desirable attributes that distinguish them from the original border forsythia. But before we chat about these various cultivars, let’s first talk about their needs in the landscape. The border forsythia is a vigorous, long-lived shrub with a fast rate of growth. It can be located in full sun or light shade, but it will flower best in full sun. Forsythia grow best in well-drained soil, but will tolerate tougher conditions. They do require spring and summer irrigation in our region.

Hardiness varies with the cultivar, but generally they are hardy in USDA Zones 6 through 8. In colder zones, the flower buds that are not protected by a blanket of snow, will be killed by severely cold temperatures.

The typical old border forsythia are quite large and unruly. The one in my front landscape is no exception. I have to prune out one-third of the oldest canes every year and whack (prune judiciously and severely) it back every year to keep it from taking over its area of the landscape. Large traditional border forsythia like mine should be planted where they have the room to grow. (Mine was planted there before we moved in 19 years ago.) If room isn’t available, its better to plant one of the more tidy or smaller cultivars.

Here are some of the cultivars of forsythia you can find at nurseries or from garden catalogs.

Lynwood

or ‘Lynwood Gold

(Forsythia x intermedia): This is one of the most common cultivars and a traditional favorite. It has big golden yellow flowers along the entire length of the stems. It grows from 6 to 10 feet in height. It has the traditional border forsythia habit that is both sprawling and erect. Zone 5.

‘Beatrix Farrand’(Forsythia x intermedia): is also a large vigorous shrub growing from 8 to 10 feet in height with large (two inches or bigger) deep golden yellow flowers. Zone 5.

New Hampshire Gold

(Forsythia ovata) : While this shrub is still pretty big, growing about five feet tall, it’s more finely branched and pendulous, forming a more compact mound that is a ball of yellow in the spring. It’s extremely flower hardy, with flower buds able to tolerate temperatures of 35 degrees below zero. It also supposedly develops a nice red to purple fall color. Zone 4.

‘Golden Peep’ (Forsythia x intermedia ‘Cordijeau’) : This is a semi-dwarf cultivar from France that forms a compact 18 to 30 inch tall, rounded mound. It’s much easier to incorporate into today’s landscapes. Zone 5.

‘Gold Tide’ (Forsythia x intermedia ‘Courtasol’) : New from France, this two-foot tall dwarf forsythia is a spreading shrub that can be used as a ground cover. The lemon-yellow flowers are abundant in early spring. The leaves are feathery and light green, making them more attractive than the usual forsythia foliage. Zone 5.

‘Goldilocks’ (Forsythia x intermedia ‘Courtacour’) : Another new forsythia from France, this newcomer is quite distinctive. It produces yellow-flowered stems that spike straight upwards. The shrub grows from two to three feet in height. Zone 5.

‘Kumson’ (Forsythia viridissima koreana): This new forsythia comes from Korea and has interesting foliage. The leaves are dark green and the veins are silvery white. The shrub has an upright arching form and grows from 4 to 6 feet in height. The distinctive foliage makes this shrub a standout in the landscape. Zone 5.

‘Week End’ (Forsythia x intermedia ‘Courtalyn’): This is a mutant cultivar achieved by radiating ‘Lynwood’ with gamma rays. The result was a shrub with lots of large flowers but without the wild branching of the original plant. Zone 5.

These are some of the newest and most popular forsythia cultivars. If you can’t find the one you want at a local nursery, you can mail order most of these cultivars from Forest Farm in William, Oregon. Contact them at 541-846-7269 or check out their web site at www.forestfarm.com.

FYI:

One of the nice things about forsythia is that you can take cuttings of branches and “force” them into bloom. Anytime after January, cut some branches from your forsythia and bring them indoors. Place them in water, removing any buds that are below the water line. The flowers will open in a little over a week.

You may not have noticed before but the stems of forsythia are hollow. Do don’t be alarmed and think that borers are at work on your shrub.

Published: 10/29/2005 11:35 AM

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