Introduction
There is nothing quite like the first dahlia bloom of the summer. Whether you are growing a massive dinnerplate dahlia with flowers the size of a dinner plate or a delicate pompon type, these plants are the undisputed stars of the late-summer garden. The vibrant colors and intricate petal patterns provide a sense of accomplishment that few other flowers can match. At Longfield Gardens, we want to help you take that excitement even further by showing you how to turn a few beautiful flowers into an explosion of color that lasts until the first frost.
Dahlias are unique because they actually reward you for being an active gardener. While some plants prefer to be left alone, dahlias thrive when you interact with them through "pinching," feeding, and regular harvesting. This guide is designed for home gardeners who want to maximize their flower production, whether you are growing for backyard beauty or for stunning indoor bouquets.
By focusing on a few key techniques and understanding the natural growth habits of these plants, you can significantly increase the number of buds your plants produce. With the right approach to care and maintenance, your garden will become a prolific source of blooms all season long.
Start with a Strong Foundation: Sunlight and Soil
Before we dive into the specific techniques for increasing flower count, we must ensure the plants have what they need to perform. A dahlia plant that is struggling for light or sitting in soggy soil will never reach its full blooming potential, no matter how much you pinch or fertilize it.
The Importance of Full Sun
Dahlias are sun-loving plants that require at least six to eight hours of direct sunlight every day. Sunlight is the engine that drives flower production. If a plant is in too much shade, it will spend its energy stretching toward the light, resulting in tall, spindly stems and very few flowers. If you find your plants are leaning or look "leggy," they are likely asking for more sun. For the most productive garden, choose the sunniest spot available.
Drainage and Soil Health
Dahlias need soil with excellent drainage. In gardening, "drainage" simply means how fast water moves through the soil and away from the roots. Dahlias have fleshy tubers that store energy, and if these tubers sit in water for too long, they can suffer. We recommend planting in loose, friable soil that is rich in organic matter, such as compost.
Good soil allows the root system to expand easily. A larger, healthier root system can support more top growth, which ultimately leads to more flowers. If you have heavy clay soil that stays wet, consider planting in raised beds. This simple change can make a massive difference in how many blooms you see later in the season.
Key Takeaway: Success begins with placement. Ensure your dahlias have a minimum of six hours of direct sun and soil that never stays soggy.
The Secret to More Flowers: Pinching
If you only do one thing to get more blooms from your dahlias, it should be pinching. Also known as topping, pinching is a simple pruning technique that changes the way the plant grows. While it might feel counterintuitive to cut a healthy, growing plant, this is the most effective way to transform a single-stemmed plant into a lush, multi-stemmed flower machine.
Why Pinching Works
Naturally, a dahlia plant wants to grow one main central stem that leads to a single terminal bud (the first bud at the very top). This is called apical dominance. By removing that top sprout, you break this dominance. The plant responds by sending its energy into the "lateral" buds, which are the small growth points located where the leaves meet the stem.
Instead of one tall stalk, you end up with four to six main branches. More branches mean more locations for flower buds to form. This also creates a shorter, sturdier, and more "bushy" plant that is less likely to fall over in a summer breeze.
How and When to Pinch
The best time to pinch your dahlias is when they are between 8 and 12 inches tall and have developed about four sets of true leaves.
- Locate the center: Look for the main central stem and the very top sprout of new growth.
- Make the cut: Using a clean pair of garden snips or your thumb and forefinger, remove the top 2 to 3 inches of the center stem. Be sure to cut just above a pair of leaves.
- Observe the change: Within a week, you will see new stems emerging from the leaf joints below your cut.
What to do next:
- Check your plants weekly once they reach 6 inches in height.
- Wait until the plant has at least four pairs of leaves before pinching.
- Use clean snips to prevent the spread of any garden diseases.
- Don't worry about "losing" that first bud; you are trading one early flower for dozens of later ones.
Feeding for Flowers: Proper Fertilization
Dahlias are "heavy feeders," meaning they require a good amount of nutrients to sustain their rapid growth and heavy flowering schedule. However, not all fertilizers are created equal. If you use the wrong type, you might end up with a giant green bush but very few actual flowers.
Understanding NPK
Most fertilizers list three numbers on the package, known as the NPK ratio. These stand for Nitrogen (N), Phosphorus (P), and Potassium (K).
- Nitrogen (N) promotes green, leafy growth.
- Phosphorus (P) supports root development and flower production.
- Potassium (K) helps with overall plant health and vigor.
The Nitrogen Trap
In the early summer, a little nitrogen is fine to help the plant get established. However, once the plant is about a foot tall, you should avoid high-nitrogen fertilizers. Too much nitrogen encourages the plant to stay in a "vegetative" state, focusing only on leaves. To get more blooms, switch to a fertilizer that is higher in phosphorus and potassium. Look for a "bloom booster" formula or a balanced organic fertilizer with a lower first number (such as 5-10-10 or 10-20-20).
Timing Your Fertilizer
We recommend starting a regular feeding schedule once the plants are established. Feeding once a month is usually sufficient. Always follow the instructions on the product label, as over-fertilizing can be just as counterproductive as not fertilizing at all. If you see the leaves turning very dark green and soft, you may be overdoing the nitrogen. If the plant looks pale and growth is slow, it might need a boost of balanced nutrients.
Watering for Consistent Production
Watering is a foundational part of dahlia care, but it must be done correctly to keep the blooms coming. Dahlias have a high water content in their stems and petals, so they cannot produce beautiful flowers if they are thirsty.
Deep Watering vs. Frequent Splashing
The goal is to keep the soil consistently moist but not saturated. Instead of giving your plants a light sprinkle every day, it is better to water deeply two or three times a week. This encourages the roots to grow deeper into the soil, making the plant more resilient and better able to support a heavy load of flowers.
Avoid the Foliage
Whenever possible, water the soil at the base of the plant rather than spraying the leaves and buds from above. Wet foliage can encourage powdery mildew and other fungal issues, which can stress the plant and reduce flower quality. Using a soaker hose or a watering wand is an easy win for keeping your dahlias healthy.
Mulching for Moisture
Applying a layer of organic mulch, such as shredded bark or straw, around the base of your dahlias helps regulate soil temperature and retain moisture. This is especially helpful during the heat of mid-summer. A cool, moist root zone keeps the plant "happy" and productive during July and August when many other plants might start to fade.
Deadheading: The "Never-Ending" Cycle
One of the most important rules for getting more blooms is to never let the plant go to seed. When a flower fades and begins to dry out, the plant starts putting its energy into producing seeds. This signal tells the plant that its job for the season is nearly done, and it will stop producing new buds.
How to Deadhead Correctly
"Deadheading" is the process of removing spent or faded flowers. To keep the plant producing, you must remove these old blooms as soon as they start to wilt.
The trick with dahlias is telling the difference between a new bud and a spent flower head.
- New buds are usually round and firm.
- Spent flowers (the ones you want to remove) are often pointed or cone-shaped and feel soft or "squishy" to the touch.
When you remove a spent flower, don't just snip off the head. Cut the stem back to a point where it meets a main branch or a new set of leaves. This keeps the plant looking tidy and encourages new growth from that junction.
Cut Flowers for the House
The best way to "deadhead" is actually to harvest fresh flowers for bouquets! Dahlias are one of the few plants where the more you cut, the more they bloom. By regularly harvesting stems for your vases, you are essentially performing a continuous pruning that keeps the plant in a high-production mode.
Key Takeaway: A dahlia's goal is to make seeds. By removing flowers before they can do that, you force the plant to keep trying, which results in a continuous supply of new buds.
Disbudding: Quality vs. Quantity
While pinching increases the total number of flowers, a technique called "disbudding" helps improve the quality and size of those flowers. This is particularly useful for decorative dahlias or for gardeners who want long, straight stems for floral arrangements.
How Disbudding Works
Dahlias typically produce buds in clusters of three: one large "terminal" bud in the center and two smaller "lateral" buds on either side. If you leave all three, the plant divides its energy between them. The resulting flowers may be smaller, and the stems may be shorter because the side buds compete for space.
To disbud, you simply use your fingers to gently flick off the two smaller side buds, leaving only the large central one. This directs all the nutrients and energy into that single flower. It will grow larger, and the stem will grow longer and stronger because it doesn't have to support the weight of multiple blooms at one point.
Which Varieties Benefit Most?
- Dinnerplate Dahlias: Disbudding is highly recommended if you want those iconic, massive blooms.
- Cactus and Semi-Cactus Dahlias: These often look better when disbudded, as it highlights their unique petal shapes.
- Ball Dahlias: These are usually grown for quantity, so many gardeners skip disbudding for these types.
Supporting Your Prolific Plants
As you follow these steps, your dahlia plants will become heavy with foliage and flowers. Because dahlia stems are hollow, they can be fragile. A sudden rainstorm or a heavy wind can easily snap a stem that is loaded with blooms.
Staking Early
It is always easier to support a plant before it needs it. For tall varieties, we recommend placing a sturdy stake (wood, bamboo, or metal) in the ground at the time of planting. As the plant grows, use soft garden twine to loosely tie the stems to the stake every 12 to 18 inches.
The Tomato Cage Method
For bushier dahlias that have been pinched, a heavy-duty tomato cage can be an excellent support system. The cage supports the lateral branches and keeps the entire plant upright, ensuring that the flowers stay off the ground and remain visible.
What to do next:
- Install stakes or cages when plants are about 12 inches tall.
- Check ties throughout the season to ensure they aren't too tight as the stems thicken.
- Provide extra support to dinnerplate varieties, as the flowers themselves add significant weight.
Troubleshooting Low Bloom Counts
Sometimes, despite your best efforts, a dahlia plant might seem reluctant to bloom. If you find yourself looking at a lot of green leaves but no buds, check these three common factors.
1. Excess Nitrogen
As mentioned earlier, high-nitrogen fertilizers are the most common cause of "all leaves and no flowers." If you suspect this is the case, stop fertilizing for a few weeks and then switch to a phosphorus-heavy formula.
2. High Temperatures
Dahlias love the sun, but they can get stressed by extreme heat (consistently over 90°F). When it is very hot, the plant may go into a temporary "dormancy" to save moisture, causing it to stop producing buds. If you live in a very hot climate, ensure the plants are well-watered and consider using mulch to keep the roots cool. Once the temperatures drop slightly, the blooming should resume.
3. Pest Pressure
Insects like thrips or aphids can sometimes damage tiny developing buds before you even see them. If the tips of your stems look distorted or "burnt," inspect them closely for small pests. Often, a strong blast of water from the garden hose is enough to dislodge these visitors and allow the plant to get back to the business of blooming.
Realistic Expectations for the Season
It is helpful to remember that dahlias are "short-day" plants. This means they naturally bloom more profusely as the days begin to shorten in late summer and early autumn. While you may get some flowers in July, the real "dahlia show" typically happens from August through October.
The exact timing of your first and last blooms will depend on your local weather and when you planted your tubers. If you had a late, cool spring, your plants might take a little longer to get started. Conversely, a warm, long fall can lead to your best harvest of the year. Patience is part of the process, and the wait is always rewarded when those late-season colors finally emerge.
Conclusion
Getting the most out of your dahlias is a rewarding journey that blends simple science with a little bit of garden art. By focusing on the basics—plenty of sun, the right nutrients, and the simple act of pinching—you can transform your garden into a floral powerhouse. Remember that these plants want to bloom; your job is simply to provide the support and the cues they need to keep going.
Regularly harvesting your flowers not only fills your home with beauty but also tells the plant to keep producing. At Longfield Gardens, we believe that every gardener can achieve a stunning display by following these practical steps. The more you engage with your dahlias, the more they will give back to you in a spectacular parade of color that lasts until the very end of the season.
- Pinch early: Cut the main stem when the plant is 8-12 inches tall to encourage branching.
- Feed correctly: Use a low-nitrogen, high-phosphorus fertilizer once the plant is established.
- Cut often: Harvesting flowers for bouquets actually stimulates the plant to produce more buds.
- Deadhead regularly: Remove faded flowers to prevent the plant from wasting energy on seed production.
"A dahlia garden is a work in progress that rewards every small effort with a burst of color. The secret to more blooms is simply to stay involved with your plants throughout the summer."
We invite you to explore our wide selection of dahlia varieties to find the perfect colors and shapes for your own garden oasis this year.
FAQ
Does pinching dahlias delay the first bloom?
Yes, pinching typically delays the very first flower by about two weeks. However, this short wait is worthwhile because it results in a much sturdier plant with significantly more flowers over the course of the entire season. Instead of one early bloom on a lanky stem, you will eventually have dozens of blooms on a bushy, productive plant.
Can I get more blooms by watering more often?
While dahlias need consistent moisture, over-watering can actually lead to root rot and poor health. The key is deep, thorough watering that reaches the root zone, rather than frequent light sprinkling. Keeping the soil moist but not soggy ensures the plant has the hydration it needs to produce lush, water-heavy flower petals without stressing the tubers.
Why are my dahlia flowers getting smaller as the summer goes on?
Smaller flowers can be a sign that the plant is running low on nutrients or is stressed by high heat. Ensure you are following a regular feeding schedule with a fertilizer high in phosphorus and potassium. Also, make sure you are deadheading spent blooms promptly, as allowing the plant to start producing seeds will naturally decrease the size and quantity of new flowers.
Is it too late to pinch my dahlias if they are already two feet tall?
While it is best to pinch when the plants are 8 to 12 inches tall, you can still pinch or "top" a taller plant if it hasn't started blooming yet. If the plant is already very tall and thin, cutting it back will still encourage lateral branching, although the stems may be thicker and the plant's shape may be less symmetrical than if it had been pinched earlier. Regardless of the height, removing the top growth will always signal the plant to branch out.
