Delphiniums, commonly confused with Larkspur flowers, are stunning perennial flowers that add a touch of elegance and grace to any garden. With their tall spikes adorned with vibrant blue, purple, white, or pink blossoms, Delphiniums are a true showstopper. Originally native to the Northern Hemisphere, these beauties have been captivating gardeners for centuries with their stately presence and unique charm. Learn how to grow and care for Delphinium.
Delphiniums are exceptional choices as cut flowers for floral arrangements, captivating centerpieces, and enchanting bouquets. When given the proper care and attention, cut Delphinium stems can grace a vase for up to a week, ensuring ample time to relish their beauty and elegance.
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Larkspur vs Delphinium
Larkspur and Delphinium are closely related, but they’re not exactly the same. Here’s the breakdown:
- Larkspur: This term can be a little confusing because it’s a common name shared by two different genera of plants: Delphinium (the more well-known delphiniums) and Consolida.
- Delphinium: These are the classic tall, stately flowers with elegant blooms. Delphinium is also a common name for larkspur, but not all larkspur are Delphiniums.
Here’s a table summarizing the key differences:
| Feature | Delphinium (Larkspur) | Consolida (Larkspur) |
| Genus | Delphinium | Consolida |
| Lifespan | Perennials (though some may act as biennials) | Annuals |
| Flower Spike | Denser flower clusters | Looser, more open flower arrangements |
| Color Range | Primarily blues and whites, but some cultivars offer pinks, purples, and yellows | Wider range of colors including reds, oranges, and pinks |
Some larkspur are delphiniums, but not all. It depends on the specific genus (Delphinium vs Consolida).
Delphiniums are generally the taller, showier plants with denser flower spikes.
Consolida (annual larkspur) tend to be shorter with looser flower arrangements and a wider color variety.
What Is the Best Time of Year to Plant Delphiniums?
Determining the best time to plant delphiniums hinges on the unique climate of your region. For those residing in cooler areas, early spring emerges as the opportune window. Planting during this time grants delphiniums the chance to establish themselves before the sweltering summer temperatures roll in. On the other hand, if you find yourself in a warmer climate, opting for a late summer to early fall planting schedule is advisable. This timing allows the plants to develop robust root systems before winter’s frosty embrace sets in.
Delphiniums boast a remarkable hardiness, thriving within USDA zones 3 to 7. This broad range of adaptability makes them an excellent choice for gardeners spanning various regions across the United States, from the frosty landscapes of zone 3 to the milder climates of zone 7. Whether you’re nestled in the brisk corners of Minnesota or basking in the warmth of Georgia, delphiniums can find a comfortable home in your garden.
Quickly determine your USDA hardiness zone by simply entering your zip code:
What Do Delphinium Seeds Look Like?
The seeds of delphiniums have a triangular shape, are very small, and are brown. They come from the flowers of the plant. You can store delphinium seeds for up to 2 years in a location devoid of light and with low humidity levels.
Delphinium seeds typically germinate within 2-3 weeks. The temperatures during the sowing season determine their growth rate.
We used these Delphinium seeds, which germinated quickly for us.
- This tall graceful annual, Delphinium consolida, is commonly referred to as Larkspur. It is a treasured flower with lace-like leaves and showy blooms. This variety, Rose Queen, has double blooms of a soft rose color.
What Type of Substrate Do Delphiniums Need?
Delphiniums require a substrate for seedlings composed of fertile, deep, and aerated soil. This type of substrate is essential for Delphinium care.
The substrate for seedlings is composed of 3 components. The first one is peat moss; another alternative to peat is coconut fiber. This component is going to be used in 70% of the total of the mixture. Its primary function will be to retain water and provide moisture to the soil.
The second ingredient is perlite; an alternative, if we do not get perlite, can be vermiculite. The proportion that we are going to be using, in this case, is 15% of the total of the mixture; this is going to be in charge of aerating the soil.
The last and third component that we are going to be using is the worm humus, which is going to be composed of the remaining 15% of the mixture. The humus is going to be the fertilizer in charge of providing the necessary nutrients for the development of the plant.
How to Grow Delphiniums from Seed
Starting delphiniums from seed is a rewarding process that allows you to witness their entire life cycle. The best time to sow Delphinium seeds is in late winter or early spring, typically around 8-10 weeks before the last expected frost in your area. Learn more about how to start seeds indoors.
Here are the step-by-step instructions for starting Delphinium seeds indoors:
- Prepare your seed-starting containers: Use clean trays or pots with suitable drainage holes and fill them with a high-quality seed-starting mix.
- Sow the seeds: Delphinium seeds are tiny, so sow them thinly on the surface of the seed-starting mix. Gently press them into the soil, but don’t cover them too deeply, as they need light to germinate.
- Water carefully: Use a fine mist or bottom-watering method to avoid displacing the seeds. Keep the soil consistently moist but not waterlogged.
- Provide warmth and light: Place the seed trays in a warm location (around 65-70°F) and provide adequate light. A sunny windowsill or grow lights can help encourage germination. Delphinium seeds do indeed require light to germinate. Unlike some seeds that prefer darkness, Delphinium seeds rely on exposure to light to trigger the germination process.
- Be patient: Delphinium seeds can take 2-3 weeks to germinate, so be patient and keep the soil moist during this time.
- Thin the seedlings: Once the seedlings have developed their first set of true leaves (the second set of leaves after the initial cotyledons), thin them out, leaving the strongest plants spaced 2-3 inches apart.
- Transplant and harden off: When the seedlings are 4-6 inches tall and have developed a robust root system, transplant them into larger containers or directly into the garden after hardening them off gradually to outdoor conditions.
It’s important to note that delphiniums grown from seed may not bloom in their first year, as they typically require a period of vernalization (exposure to cold temperatures) to initiate flowering. However, with proper care and patience, you’ll be rewarded with stunning blooms in the following growing season.
Hardening Off Delphinium Seedlings
When starting Delphinium seedlings indoors, you must gradually acclimate them to outdoor conditions before transplanting them into the garden. This process, known as “hardening off,” is crucial for their survival and successful establishment.
When the seedlings are about 4-6 inches tall and have developed a robust root system, usually around 6-8 weeks after sowing, it’s time to begin the hardening-off process. Here’s how to do it:
- Start with a sheltered location: Choose a spot that’s partially shaded and protected from strong winds and direct sunlight. A cold frame or a sheltered porch can work well.
- Expose gradually: On the first day, take the seedling trays outside and leave them in the sheltered location for a couple of hours, bringing them back inside afterward.
- Increase exposure: Over the next week to 10 days, gradually increase the amount of time the seedlings spend outdoors, exposing them to more direct sunlight and wind each day.
- Provide protection: If temperatures are expected to drop below 50°F (10°C) at night, bring the seedlings back inside or provide them with a protective covering, such as a cold frame or a cloche.
- Monitor moisture: During the hardening-off process, keep an eye on the soil moisture levels and water the seedlings as needed, but avoid overwatering.
- Transplant carefully: Once the seedlings have fully acclimated to outdoor conditions, usually after 10-14 days, you can transplant them into their permanent location in the garden.
Hardening off is an essential step that prepares Delphinium seedlings for the transition from the controlled indoor environment to the great outdoors.
Planting Established Delphinium Plants
If you prefer to start with established Delphinium plants, it’s essential to choose healthy specimens and follow proper planting techniques to ensure their success. When selecting Delphinium plants, look for robust, sturdy stems and vibrant, unblemished foliage. Avoid any plants that appear wilted, discolored, or damaged.
Timing is crucial when it comes to planting. The ideal seasons for planting established delphiniums are early spring or fall. This allows the roots to become well-established before the intense heat of summer or the cold temperatures of winter set in.
Here’s a step-by-step guide for planting established Delphinium plants:
- Site Preparation: Choose a location that receives full sun to partial shade (at least 6 hours of direct sunlight per day) and has well-draining, fertile soil rich in organic matter.
- Dig the Planting Hole: For each plant, dig a hole twice as wide as the root ball but only slightly deeper. This will encourage the roots to spread outward while preventing the plant from sinking too deeply into the soil.
- Amend the Soil: Mix compost or well-rotted manure into the soil you’ve removed from the planting hole. This will provide essential nutrients to support the plant’s growth.
- Plant at the Proper Depth: Carefully remove the plant from its container and gently loosen the roots. Place the plant in the hole, making sure the crown (where the stems meet the roots) is at soil level or slightly above.
- Backfill and Water: Fill in the hole with the amended soil, gently firming it around the base of the plant. Water thoroughly to settle the soil and eliminate any air pockets.
- Spacing: Delphiniums can grow quite tall and bushy, so it’s essential to provide adequate spacing between plants. A general guideline is to space them 2-3 feet apart, but double-check the specific cultivar’s mature size for optimal spacing.
- Mulch: Apply a 2-3 inch layer of organic mulch around the plants, being careful not to pile it directly against the stems. That will help retain moisture and suppress weeds.
By following these steps and providing proper care, your established Delphinium plants will have the best chance of thriving and putting on a spectacular show of blooms in the coming growing season.
How to Care for Delphinium
Proper care is essential to ensure your Delphinium plants thrive and produce an abundance of beautiful blooms year after year. From watering and fertilizing to pruning and staking, each step plays a crucial role in maintaining the health and vigor of these garden favorites.
Temperature
Delphiniums prefer cooler temperatures and struggle in extreme heat. They perform best when daytime temperatures range between 60°F and 75°F (15°C to 24°C). In hot climates, providing afternoon shade or growing them in a partially shaded area can help prevent stress and wilting.
Light
These tall, stately plants require ample sunlight to support their growth and flowering. Ideally, delphiniums should receive at least 6 hours of direct sunlight per day. In extremely hot regions, some afternoon shade may be beneficial, but they generally prefer full sun conditions.
Watering
Delphiniums require consistent moisture, especially during their active growing and flowering periods. Water deeply and regularly, aiming to keep the soil evenly moist but not waterlogged. Yellowing or wilting leaves can be signs of overwatering or underwatering, respectively. Adjust your watering schedule accordingly. Learn more about the best time to water plants.
Fertilizing
Regular fertilization supports the vigorous growth and abundant blooms of delphiniums. Apply a balanced, slow-release fertilizer in early spring, followed by a side-dressing of compost or well-rotted manure around mid-summer. Avoid high-nitrogen fertilizers, as they can promote excessive foliage growth at the expense of flowers. Learn more about fish fertilizer for plants.
- Encourages Budding And Blooming For Abundant And Colorful Flowers
Pinching, Pruning, and Deadheading
Proper pruning and deadheading are essential for keeping your delphiniums looking their best. After the initial flush of blooms has faded, cut the spent flower spikes back to just above a set of healthy leaves. That encourages the plant to produce additional flushes of flowers and prevents it from going to seed prematurely. In late fall, cut the entire plant back to a few inches above the ground to prepare for winter dormancy.
Pinching delphiniums can encourage more blooms. Here’s the thing to know:
- Timing: The ideal time to pinch delphiniums is early spring, just when new growth is about 6-8 inches tall.
- Pinching method: Make a clean cut with sharp pruners just above a healthy set of leaves. You’re basically removing the top inch or two of new growth.
Pinching encourages lateral buds lower down the stem to develop, which will eventually produce flowers. That can lead to more blooms overall and a bushier plant.
Staking and Support
Delphiniums can grow quite tall, sometimes reaching heights of 6 feet or more. It’s essential to provide proper staking or support to prevent them from toppling over or becoming damaged by wind or heavy rain. Use sturdy bamboo canes or metal plant supports, placing them around the plants early in the growing season before the stems become too tall and unwieldy.
Tips for Harvesting Delphiniums for Flower Arrangements, Bouquets and Centerpieces
- Cutting time: The ideal timing for cutting delphiniums for arrangements is when the bottom florets (the small flowers) on the flower spike have just begun to open. This stage ensures the blooms will open further in the vase but will also last longer.
- Making the cut: Use sharp pruners or shears to make a clean cut at a 45-degree angle on the stem. This angled cut helps maximize water uptake in the vase.
- Stem selection: Choose stems that are straight and sturdy. Avoid any stems that are weak, damaged, or diseased.
- Length: The length of the stem you cut will depend on your desired vase arrangement. For taller centerpieces, you can cut stems up to 3 feet long. For smaller bouquets, 1-2 feet is appropriate.
- After cutting: Immediately after cutting, place the stems in a clean vase filled with cool water. You can add a floral preservative solution to the water to extend the vase life of your delphiniums.
Here are some extra tips for long-lasting cut delphiniums:
- Recutting stems: Every few days, recut about an inch off the stem diagonally and change the water in the vase. That helps prevent stem blockage and keeps the flowers fresher for longer.
- Location: Avoid placing your arrangements in direct sunlight or drafty areas.
- Temperature: Keep the arrangements in a cool location away from heat sources.
By following these tips, you can enjoy beautiful Delphinium bouquets and centerpieces in your home for a significant amount of time.
Recommended reading: How to Start a Cut Flower Garden: Plan and Layout
Common Problems and Solutions
While delphiniums are generally hardy and low-maintenance plants, they can still encounter various issues that may affect their health and appearance. From pesky pests to environmental stressors, it’s important to be aware of the common problems these plants face and be prepared with the appropriate solutions.
Pests and Diseases
Like many garden plants, delphiniums are susceptible to certain pests and diseases. Common pests include aphids, thrips, and spider mites, which can be controlled with insecticidal soap or neem oil. Diseases such as powdery mildew, leaf spot, and stem rot can be prevented by providing adequate spacing, avoiding overhead watering, and removing any affected plant material promptly. Learn more about how to mix neem oil for plants.
Environmental Issues
While delphiniums are generally hardy plants, they can struggle in extreme heat and drought conditions. Providing ample water and mulching around the plants can help mitigate these issues. Additionally, strong winds and heavy rains can cause damage to the tall flower spikes, making proper staking even more crucial.
Final Conclusions
Delphiniums are a true garden treasure, offering a stunning display of color and elegance that is hard to match. With their towering spikes and vibrant blooms, they add a touch of drama and sophistication to any landscape. By following the proper planting and care techniques, you can enjoy the beauty of these remarkable flowers for years to come. Whether you’re a seasoned gardener or a beginner, delphiniums are a rewarding addition to any garden, providing a breathtaking focal point that is sure to captivate and delight.
Frequently Asked Questions
Delphinium blooms typically last for several weeks, with each flower spike lasting anywhere from 2-4 weeks. Proper deadheading can encourage additional flushes of blooms throughout the growing season.
Delphiniums are perennial flowers, meaning they will come back year after year if grown in the appropriate hardiness zones and with proper care.
Yes, delphiniums can be grown in containers, but they may require more frequent watering and fertilization. Choose a large container with good drainage and use a high-quality potting mix.
Over time, delphinium clumps may become overcrowded and benefit from being divided every 3-4 years. Divide the plants in early spring or fall, replanting the divisions with adequate spacing.
Delphinium heights can vary greatly depending on the cultivar, but most varieties range from 2-6 feet tall when mature.
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