Delphiniums are one of my all-time favorite garden flowers. These tall blooming perennials have beautiful blue, purple and white flowers. Their tall and colorful blooms are a sure sign of summer. I normally plant them in the back of garden beds, providing a glorious floral backdrop to the rest of the garden.
But, if you are short on space, delphiniums can also be successfully planted in pots or containers. Because they grow upwards and don’t have a rapid spreading rate, they make a great option for container gardens if you live in the right hardiness zone for the variety you’ve chosen.
If you’ve decided you’d like to add some delphiniums to your space limited garden, you’ve come to the right place. Follow along as I outline how to grow delphiniums in pots or containers in eight simple steps!
Delphiniums are one of the most beloved garden flowers, with their tall spires of vibrant blue, purple, pink, white or red blossoms. Their majestic blooms add height, color and drama to any garden.
While delphiniums are best known as in-ground garden plants, they can also make stunning container specimens if given proper care Here is a complete guide on successfully growing delphiniums in pots
Choosing the Right Pot
When selecting a container, it’s important to choose one that is large enough to accommodate the delphinium’s taproot and provide good drainage. Plastic, terracotta and glazed ceramic pots with drainage holes work well. For mature plants, choose a pot that is at least 12-16 inches wide and 10-14 inches deep.
Delphiniums dislike sitting in soggy soil so make sure the pot has adequate drainage holes. You can add extra holes with a drill if needed. Raising the pot up on pot feet or bricks improves drainage. Self-watering containers are not recommended, as they tend to stay too wet.
Best Varieties for Containers
While some delphinium species can grow 6 feet tall or higher, compact dwarf and medium-sized hybrids are better choices for pots. Good options include:
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Magic Fountains Series – Grows 12-32 inches tall. Wide range of colors.
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Aurora Series – Grows 24-40 inches tall. Pure white, blue, dark blue and pink varieties.
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Summer Skies Series – Grows 32-40 inches tall. Blue, white, pink, purple and bicolors.
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Blue Lace Series – Grows 32-40 inches tall. Light blue and purple blue varieties.
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Guardian Series – Grows 32-40 inches tall. Dark blue, light blue, white and bicolors.
For the best results, look for container-specific delphinium cultivars bred to thrive in pots. Avoid large flowered exhibition types that require staking.
The Right Potting Mix
Delphiniums need a very well-draining soil mix in containers. A good quality potting mix formulated for perennials is ideal. You can make your own by mixing equal parts peat moss, compost and perlite. For moisture retention, add a little coconut coir.
Before potting, place crocks, pebbles or packing peanuts at the bottom of the container for extra drainage. Fill the pot about 1/3 full with potting mix, set the root ball on top and fill around it with more mix, packing down gently.
Watering and Feeding
Consistent watering is crucial for container delphiniums. Allow the soil to dry out slightly between waterings, but don’t let it become bone dry. Drooping leaves indicate under-watering. Water thoroughly until it drains from the bottom of the pot.
Feed every 2-3 weeks with a balanced liquid fertilizer diluted to half strength. Look for a formula higher in phosphorus to promote flowering. Stop feeding 6-8 weeks before your first expected fall frost.
Location and Support
Site your potted delphiniums in a spot with at least 6 hours of direct sunlight daily. Some afternoon shade is ideal to prevent leaf scorch. Shelter from strong winds helps prevent toppling.
Insert bamboo stakes around the inner edges of the pot when first planting. As the stems elongate, tie them gently to the stakes for support. Avoid staking through the main root area. Green painted stakes blend in well.
Deadheading and Grooming
Deadheading spent blooms promotes reblooming on some varieties. Cut back each flower stalk to just above the first set of full, healthy leaves. Always remove any yellowing leaves or stems to keep plants looking their best.
Pinching or cutting back leggy growth while young encourages bushier plants. Stop pinching once flower buds form to avoid removing them. Removing faded flowers and trimming off tattered foliage will keep potted delphiniums looking tidy.
Overwintering Care
In zones 3-7, keep plants outdoors in their pots over winter. Place in a sheltered spot and maintain some water. Cut stems back to 6 inches after several hard frosts.
Mulch the soil surface with 2-3 inches of shredded leaves, straw or evergreen branches for insulation. Wrap or cover the pots with burlap or bubble wrap if temperatures drop below freezing for extended periods.
In warmer zones, delphiniums will thrive year-round in pots. Just make sure they don’t sit in waterlogged soil over the rainy season. Move to partial shade if leaf scorch occurs.
Dividing and Propagation
Dividing pot-bound delphinium clumps every 2-3 years in early spring rejuvenates them. Carefully wash off the soil and use a sharp, sterilized knife to cut the root ball into sections with 3-5 growth buds each. Replant in pots using fresh potting mix.
Take 4-6 inch tip cuttings in early summer, dip in rooting hormone and pot up in seed starting mix. Place under a plastic dome or bag until rooted. Plant out in fall.
Delphinium seeds can be started indoors 6-8 weeks before last frost. Press into soil, do not cover. Move outdoors after danger of frost. Plants will bloom the second year from seed.
Common Problems
Powdery Mildew – Avoid wetting foliage. Improve air circulation. Apply neem oil or sulfur sprays preventatively.
Aphids – Check for clusters on buds and stems. Knock off with a strong spray of water. Apply insecticidal soap weekly if needed.
Slugs and Snails – Pick off by hand. Set out shallow dishes of beer to trap. Spread diatomaceous earth around pots.
Wind damage – Shelter plants from strong winds. Stake tall varieties as needed.
Root rot – Allow soil to dry between waterings. Ensure pot has drainage. Drench soil with fungicide if rot occurs.
With the right variety, pot, watering routine and care, delphiniums can thrive and put on a spectacular display in containers. Their vertical nature makes them ideal specimens for adding height and drama to potted arrangements and small space gardens.
Step 1: Choose Your Container
Pick a large pot that provides decent drainage.
Choosing a container for a potted delphinium will take some thought. First, make sure whatever pot you choose, it has drainage. Delphiniums do not like sitting in water. They like to be evenly moist and never dry, but sitting in water will cause them to turn yellow and die.
Second, get a pot of substantial size. They do not like being smooshed into a pot. Their roots need some room to spread out. Another reason for a larger pot is that they also do not like drying out.
They will dry out much faster if they are in a small pot. And finally, delphiniums are a tall narrow flower, a bigger pot will provide some stability to the flowers, so they don’t tip over in every gust of wind.
Step 3: Pick The Right Variety
The popular ‘Summer Nights’ variety is excellent for planting in containers.
Not all varieties of delphinium are suited for containers. There are hundreds of varieties. The taller varieties will bend and snap. Or they need staking, which doesn’t look great in a container on the patio.
Also a tall variety in a container that is near a seating area will be too tall to enjoy, you want the flowers at eye level. Tall varieties are better suited for in the garden, or in a large pot placed farther away from seating areas.
I recommend a dwarf variety for container growing. These varieties only grow about a foot tall. It makes them less likely to snap off, and gives a nice bushy lush look to containers.
Give Delphinium Grandiflorum ‘Summer Nights’ a try. It features delicate lacey foliage and small sprays of a dark indigo blue color. It grows about a foot high and flowers for a longer period than some of the taller varieties.
3 Tips for Growing Delphiniums
FAQ
Do delphiniums come back every year in pots?
Delphiniums will bloom every year with the proper care, for example, enough water and pruning after they bloom.
Can delphinium take full sun?
Plant them in a spot that receives full sun, and be sure to water and fertilize them. They prefer cool weather, with the seeds germinating in the winter and blooming in early spring. Don’t worry about protecting delphinium from cold, unless temperatures drop into the mid-20s.
How much room do delphiniums need?
| Common Name | Delphinium |
|---|---|
| Temperature Range | -35 to 75F |
| Spacing | 6-12″. 18″ in cool summer locations. |
| Soil Preference | Fertile, moisture retentive soil. |
| Day Length | Facultative long day. |
Can delphiniums grow in pots?
One challenge when growing delphiniums in pots is that they have sensitive root systems and very much dislike overcrowding. Another challenge is that these plants can grow rather tall, and so can be vulnerable to falling over, or being toppled by strong winds, as Home Farm Plants owner & delphinium specialist Graham Austin shares:
How do you grow a Delphinium in a container?
Try and stake it early on. It is easier to place the cages and stakes on with less risk of bending and snapping the stalks of flowers. Also for container grown delphinium try and find green stakes or cages, or natural bamboo stakes.
How do I choose a potted Delphinium?
Pick a large pot that provides decent drainage. Choosing a container for a potted delphinium will take some thought. First, make sure whatever pot you choose, it has drainage. Delphiniums do not like sitting in water. They like to be evenly moist and never dry, but sitting in water will cause them to turn yellow and die.
Can delphiniums be planted in the ground?
Graham Austin is a Delphinium expert and RHS 2022 Gold Medalist who is the owner of Home Farm Plants, a specialist plant nursery. Delphiniums usually do best when planted in the ground but they can also be grown in suitable containers.
Are delphiniums easy to grow?
Offering towering flowers and vivid colours, Delphiniums command their space in the garden with ease. These plants grow in beds and borders but can also be grown successfully in large pots. They may look like a lot of work, but they are quite easy to grow, as I will show in this guide.
Are delphiniums drought tolerant?
As a drought-tolerant perennial, delphiniums are well-suited to the relatively confined environment of pots or containers. Its root system allows it to thrive in limited soil volume, while its resilience enables it to withstand fluctuations in moisture levels and temperature, making it a perfect candidate for container gardening. 2.