Forsythia Rejuvenation Pruning: Tips On Hard Pruning Forsythia Bushes

You probably have an old forsythia, or know someone that does, in the landscape. While these start out as attractive landscape shrubs, over time they can lose their luster. Keep reading to learn more about hard pruning forsythia bushes once they’ve outgrown their space.

Rejuvenating Old Forsythia Shrubs

Forsythia shrubs are known for their excellent display of bright yellow flowers in late winter or early spring. These fountain shaped shrubs originated in Korea and China. They are deciduous and typically stand 6-10 feet (2-3 m.) tall. There are a couple dozen cultivars that come in a variety of sizes as well as leaf and flower color. Forsythias are great for screening out unsightly views and are excellent in the back of a mixed border planting.

All that being said, forsythias look best with annual pruning maintenance. Like many large flowering shrubs, they can grow leggy, woody and rangy over time. It is important to know how to rejuvenate forsythias so you can bring back their attractive natural form and encourage more robust flowering.

When and How to Rejuvenate a Forsythia

One form of forsythia rejuvenation pruning is to remove one-third of all the branches at their base. Some people suggest you do this regularly once the shrub is mature. Remove the oldest, branches as they produce fewer flowers over time.

You can also remove any branches that cross over the others or look weak and unhealthy. This type of rejuvenation, which is called thinning, will encourage new branches to form. Thin your forsythia in late fall or early spring before the flowers form. Since forsythias bloom on old wood (stems that formed the previous summer), you’ll still have the remaining branches for flower display. New branches will have to be thinned if you get too many. Keep the healthiest looking ones. They will bloom their second year.

If you are wondering when to hard prune forsythias, the best answer is when the shrub gets really rangy-looking, is overgrowing its space or has dramatically reduced flowering due to old age. Hard pruning forsythias is best done in late fall. It is actually an easy technique. You simply cut all the branches to the ground. A whole new set of branches will emerge the following spring. Once they have grown in, select the best branches to keep. You will once again have a fresh-looking, young plant with more productive flowering.

Please note that hard pruning forsythia shrubs will cause you to lose one season of blossoms. Remember, they bloom on old wood. Another caveat is that if your forsythia is really old or otherwise unhealthy, it may not respond to hard pruning rejuvenation. It may die. So there is a bit of risk with forsythia rejuvenation pruning. You can rejuvenate your forsythia every three to five years.

Forsythia plants are happy plants. They tell us spring is here or at least just around the corner. Take care of them and they will bring you years of spring time happiness.

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My Forsythia Has Died, Should I Cut it Back to the Ground?

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Wildly unkempt and vibrantly yellow, forsythias (Forsythia x intermedia) are one of the first plants to burst into bloom in early spring. Prized for their golden blooms, which appear before the leaves, these shrubs are relatively hardy – they will tolerate almost any soil conditions, according to Clemson Cooperative Extension, and will even compete successfully with tree roots.

Still, like any plant, they can die if their basic growing needs aren't met, or if they simply get too old. Forsythias grow in United States Department of Agriculture hardiness zones 5 to 8, or sometimes zone 9, depending on the cultivar.

Cutting back forsythia to the ground, even if it is still alive, will not kill it rather, new sprouts will grow from the base. If the plant is really dead, either cut it back to the ground or dig out the roots to make room for another plant.

When is rejuvenation pruning needed?

This radical form of pruning is used when shrubs are overgrown, unsightly, dying in the interior and/or have stopped (or greatly reduced) producing flowers. This typically happens to fast-growing, multi-stemmed shrubs if they haven’t been properly pruned for several years.

Rejuvenation pruning gives these shrubs a fresh start. After stems have been removed down to the ground, the shrub quickly begins to regrow. Flowering shrubs produce more blossoms in following years and shrubs with colorful stems, such as dogwoods, tend to grow back brighter and more colorful after rejuvenation pruning.

How to Trim Lilac, Rose of Sharon and Forsythia Bushes

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Lilac (Syringa vulgaris), Rose of Sharon (Hibiscus syriacus) and forsythia (Forsythia) are deciduous flowering shrubs that grow in U.S. Department of Agriculture plant hardiness zones 3 through 8, 5 through 9, and 5 through 8, respectively, depending on cultivar. Lilac boasts fragrant purple or white flowers and is a spring-bloomer like the forsythia, with its yellow flowers. Rose of Sharon is a summer-blooming woody shrub that offers many different flower colors, depending on the cultivar. All benefit from yearly renewal pruning, while lilacs and forsythia can also be cut back severely to rejuvenate older plants.

Cut back overgrown lilac or forsythia bushes to ground level or 1 to 4 inches above ground level to give older, sparsely flowering shrubs new life. Do this rejuvenation pruning early in the spring, before new growth starts.

Prune out one-third of the older stems of all three shrubs each year after flowering has stopped this will be in the spring for lilacs and forsythia and late summer or fall for Rose of Sharon. Cut the individual stems back to the base of the plant.

Head back lilac bushes at the same time as the renewal pruning. Cut stems that are taller than the rest of the shrub or that stick out. Make the cuts just above a bud, leaf node or lateral branch at the desired height on the stem. Cut at a 45 degree angle sloping downward from the point about one-quarter-inch above the bud.

Remove dead, damaged or diseased limbs at any time throughout the year. Cut dead stems back to the base of the plant. Cut damaged or diseased stems back several inches into healthy wood, making the cut just outside a bud.

Pruning Forsythia

Forsythia is a true spring favorite and never disappoints with its shocking yellow blooms atop a mass of unruly branches. This early-flowering shrub can thrive for decades on neglect but there will come a time, whether out of want or necessity, that your forsythia will require pruning. But how can you do so without dampening the ferocious spring flame these spring shrubs produce?

When this shrub does so well without detailed care, why is it necessary to prune it at all? In many landscapes, if the shrub is properly sited, it may not need pruning. Unfortunately, many people underestimate the vigorous growth of these beauties, and in just a few years it may seem crowded and overgrown in a corner, narrow bed or border. A large, unruly forsythia may also seem overwhelming in a smaller space or when paired with less vigorous plants. Damage or illness may also create a misshapen or unbalanced plant that is no longer so pleasing to the eye. In these cases, judicious pruning can rejuvenate and refresh the shrub and give new life to its part of the landscape.

Rejuvenating Forsythia

Rejuvenating an old, out of shape and poorly flowering forsythia is simple. After the shrub has finished flowering in late spring, cut all the branches back to within one foot of the ground. When branches put on new growth, reaching two feet from the ground, prune all branch tips to the first set of side shoots. This will help develop a fuller, thicker shrub for a more lush look. Be aware, however, that it will take until the second bloom season for a severely pruned forsythia to return to its former splendor.

A newer forsythia that is just a few years old can be kept in tip-top shape a bit more easily. Each spring, after it flowers, cut up to one-third of the branches back to the ground. Choose dead branches, branches thicker than your thumb and all crossed or inward facing branches. This will help create a good form with healthy air circulation and pleasing growth for years of beauty and enjoyment.

It’s easy to keep forsythia looking stunning for many years. Whether you want to make the most of the forsythia already in your yard or want to add this beauty to your landscape, stop by – our landscaping experts can help you choose the best species for your yard and needs so you can enjoy its beauty for many springs to come.

How to Prune Forsythia

There are two approaches to pruning forsythia, depending on what state it’s in.

If it’s an overgrown mess or far too large for the space then cut the whole thing down to just above the ground. That’s right – whack it to the ground. Forsythia are vigorous shrubs that quickly bounce back from this type of rejuvenation pruning (provided that the shrub is healthy to start with).

Keep in mind that forsythia are large shrubs so even with rejuvenation pruning you’re likely to quickly end up back where you started they can grow 8 feet stems in a single season!

If you want to manage the overall shape or clean up the shrub a bit then you’ll want to do some thinning. This involves cutting between ¼ and 1/3 of the oldest stems to the ground do this every year. Focus on stems that are damaged, trailing on the ground, crossing, or look out of place.

Be sure to always take a few of the larger stems out of the center of the shrub. This makes room for new growth and allows sunlight into middle of the forsythia so that it can put out leaves and flowers all over the shrub, rather than just at the tips of the branches.

Whatever you do, do not simply cut off the tips of the branches or lop them off part way down the stem. Forsythia respond to that type of pruning by putting out tons of new growth just below the cut. You’ll end up with a snarled mass of branches with flowers only at the branch tips and an even larger shrub.

Pruning Forsythia into a Hedge

Some people use forsythia as a hedge and keep it closely clipped (essentially they’re cutting off the branch tips). While I don’t recommend this (there are other shrubs that make much better hedges), this approach can work. Forsythia shrubs pruned this way have very few flowers, the interior of the hedge has only thin, tangled branches (no leaves), and they need to be sheared several times a year to keep them looking somewhat tidy. But if this appeals to you then use hedge shears or an electric hedge trimmer three or four times during the growing season whenever the shrub starts to look overgrown.

This forsythia hedge produces very few flowers and not many leaves, making it look scraggly all year long.

Step by Step: How to perform rejuvenation pruning

Deciduous shrubs require maintenance pruning to keep them healthy and in scale with their surroundings. Two techniques—extensive and gradual rejuvenation— are used to restore old, overgrown shrubs that are otherwise healthy. After rejuvenation pruning, a shrub regrows from its roots, becoming a compact, youthful plant with maximum bloom. This method is preferred for many flowering shrubs because it’s quick and easy and provides positive results. Rejuvenation pruning is typically performed every three to five years when a shrub begins to look gangly and woody.

Before attempting rejuvenation pruning, contractors should be sure the plant species will respond well to drastic pruning. Some of these plants include multistemmed shrubs, such as hydrangea, forsythia, cane-growth viburnums, honeysuckle, lilac, barberry and flowering quince. The preferred time for rejuvenation pruning is just before bud break in early spring. Heavily pruned shrubs will need extra care. Before pruning, it’s also a good idea to consider a shrub’s new appearance and the impact it will have on the landscape.

Spring flowering shrubs will not bloom the year of rejuvenation. Shrubs with a lot of dead branches will not respond well to rejuvenation pruning. If more than one-third of the branches are woody and without healthy foliage, the shrub will probably not respond.

Follow these steps to properly perform extensive or gradual rejuvenation pruning.

Step 1

Become familiar with proper pruning angles to avoid damaging the plant.

Step 2

For extensive rejuvenation, completely remove the entire plant 6 to 10 inches above the ground using heavy lopping shears and a pruning saw. Healthy shrubs will respond by sending up new shoots.

Step 3

For gradual rejuvenation, remove one-third of the oldest, unproductive branches. The next year, take half of the old, lingering stems. In year three, prune out the remainder of the old branches. While this takes longer to complete, the shrub stays more attractive throughout the process.

To download a PDF copy of this page from the magazine to use as a training tool at your company, click here.

Source: Virginia Cooperative Extension Colorado State University Extension
Illustrations: David Preiss

Watch the video: Forsythia Hedge Reduction and Rejuvination Pruning Part 2

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