Dahlias are one of many summer-blooming bulbs that can keep ornamental growers swimming in flowers well into fall. Technically grown from tubers, thousands of named varieties of dahlia exist. These cultivars range widely in bloom size, form, and color
Though dahlia care is fairly easy, there are some key bits of information that gardeners must follow to produce the best floral display possible. Among these important points is the process of understanding how and when to deadhead dahlias, when to pinch them back, and how to cut dahlias for more blooms. Let us explore each of these topics in greater detail.
Pinching Back Dahlias
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Encouraging dahlias to have a long blooming period begins early in the season, not long after planting dahlias, or when overwintered tubers have developed new growth. Many experienced gardeners choose to remove or “pinch” the growth tip of the dahlia plant. This ensures that the plant will begin to branch and become bushier by producing multiple new slimmer stems, rather than a small number of thick, hollow stems. Later in the summer, these bushier plants will be able to produce an abundance of blooms.
Not only does pinching out dahlias increase the number of blooms, but it will extend the flowering period too, as with so many buds the opening will be staggered across the plant. This will help to ensure that your dahlias keep blooming through the fall.
- To pinch out dahlias, wait until the plant has grown to at least 8 inches in height and has at least 3-5 sets of leaves.
- Identify the central – apical – bud on the main stem, which should be the largest.
- Using sharp, sterilized hand pruners – or your fingers – cut or pinch off the main bud, taking the stem back to just above a set of leaves.
- As the plant continues to grow, remove all but five shoots from the plant.
Removing stems and buds from your burgeoning plant may seem brutal, but the dahlia will soon begin to form strong new lateral shoots, and come summer the plant will be full of flower heads.
Bear in mind, you will need to fertilize dahlias to get the most out of your plants. Do this prior to planting, then a month later, and again the following month. Water frequently and remove any weeds from around the plant.
How to Deadhead Dahlias
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Once plants have begun flowering, you will need to turn your attention to deadheading dahlias. The term deadheading refers to the removal of spent or faded blooms. Removing them from the plant will prevent the production of seeds and encourage the formation of new buds.
In addition to helping to maintain the vigor of dahlia plantings, deadheading is essential to keep growing beds clean and tidy. Tidy beds may also help to keep plants free of disease, insect pressure, and other plant stressors.
The following rules can be used to deadhead all dahlia varieties:
- To deadhead dahlias, you will first need to learn how to spot spent blooms, as they can look similar to unopened flowers. New flower buds will look fresh and round, while spent blooms will appear pointer, and will feel softer if you apply pressure. There may also be one or two petals poking out through the center of spent flower heads.
- Once the dahlia blooming season has begun, check over your plants at least once a week to spot dead or fading flowers.
- Ideally, remove them as soon as they begin to wilt, which enables the plant to put as much energy as possible into producing new blooms.
- Using sterilized hand pruners, cut the flower stem down to the nearest set of leaves and dispose of the clippings.
- Where there are multiple blooms on one stem, just remove the individual dead flower heads until the others have finished blooming, then cut the whole stem back to the next sef of leaves.
- Keep deadheading through summer and fall until the plant stops producing flowers.
Harvesting Dahlias as Cut Flowers
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Dahlia blooms make excellent long-lasting cut flowers. Fortunately for growers, cutting the stems will only encourage the plants to produce more buds.
To cut flowers for a vase, growers should wait until the bloom has opened on the plant. This is essential, as most dahlia varieties will not continue to open after the stem has been cut. As with pinching, cut stems will continue to branch and produce flowers until the end of the growing season.
Experienced dahlia growers may also wish to use a technique called “disbudding” to increase the size and quality of each individual bloom. This involves removing the smaller buds in favor of the larger central buds.
