Hello fellow readers, Denise from Mt. Tabor, PA, asked why her forsythia aren’t blooming. You’re not the only one, Denise; mine hasn’t either for over two years. Non-blooming forsythia most often has to do with improper pruning. Though deer browse, not enough sunlight, improper fertilizing, or winter kill may also cause it.
Why do folks prune forsythia in unnatural shapes?
Forsythia spreads readily, which is why I never recommend planting them close to the house. They are beautiful left in their natural weeping shape at the edge of a property, for example. One of the first to bloom, the sunny yellow lights up the bland landscape welcoming Spring. They can indeed turn into unwieldy shrubs, inspiring folks to prune them into unnatural shapes or hedges.
Despite its high rating of deer resistance, darn deer will nibble the newer growth if they’re starving during snowy winters such as we’ve had. Forsythia bloom on year-old wood, meaning this year’s new growth will bring next year’s flowers. So, if deer nibbled, you’ll miss the sunny flowers. The same is true if frigid winters cause bud die-back; not likely the case this winter as snow is an excellent insulator.
Non-blooming forsythia is often from improper pruning.
Forsythia needs about six hours of sunlight to bloom. And too much nitrogen can hinder bud production. So, if you are spreading lawn fertilizers high in nitrogen (please don’t), adding phosphorus such as bone meal should help counteract the nitrogen overload. Most often, however, the lack of blooms is caused by improper pruning. Maybe you have a stealth pruner at home too, Denise?
Unknown to me, my dear Curt pruned the branches within reach several times during the summer a few years ago. The outcome – a mohawk haircut of sorts – clipped on the sides and loosely wild on top. Hey, it’s a style, and isn’t fashion a matter of taste? :^# It’s true the shrubs were getting unwieldy.
The proper way to prune forsythia each year
The proper way to prune forsythia to maintain the shrub’s graceful shape is to cut out the older branches at the plant’s base. As with most flowering woody plants, it’s best to prune soon after the bloom cycle. Never use hedge clippers to sheer the ends of forsythia as the plant will remain dense with old wood in its core, suffocating new branching and inhibiting bloom. There, there Curt.
If your forsythia is way out of control and driving you batty, you can rejuvenate them in early spring by cutting them almost to the ground. Of course, you’ll miss flowering the first year, and it’ll take a few years to return to the desired height. I gave Curt the go-ahead to rejuvenate prune after I noticed the bad haircut.
How to rejuvenate prune forsythia.
Another way to rejuvenate prune and not lose a year of sunny yellow and still maintain a hedge height is to remove a third of the oldest branches the first year, cutting them to the ground. Then, cut another third next year and another third the year following, being sure to cut back the old wood only.
In all fairness, when it came time to refresh the plants, I coached Curt to cut back the stems in random heights from four to eight inches. I used the same technique to rejuvenate prune Leatherleaf Viburnum riddled with aphids a few years ago that worked famously. I later learned cutting forsythia to the ground is the correct way. And, by the time we got to the cutting them back, it was early June. What remains of our forsythia are new stems on old wood. Not so pretty.
Rather than the familiar Forsythia x intermedia, which grows 8 to 10 feet tall and 10 to 12 feet wide, you can plant smaller cultivars such as ‘Golden Peep,’ ‘Goldilocks,’ and ‘Gold Tide’ that stay 4 feet or less. There are white and pink varieties, Abeliophyllum distichum and A. ‘Roseum’, that also stay 4 to 5 feet. That way, they’ll be no risk of bad haircuts.
You’ll enjoy the story of rejuvenating our Leatherleaf Viburnum featuring special baby robins in Reasons to Prune.