Delphiniums are some of the most elegant flowers you can grow in your garden. Also known as larkspur these tall perennials produce magnificent spires of blooms in vibrant shades of blue, purple pink, white and red. With proper care, delphiniums grown from seed can thrive for many years in the garden.
In this complete guide, we will cover everything you need to know about successfully growing delphiniums from seeds
Why Start Delphiniums from Seed?
There are several great reasons to start your delphiniums from seeds rather than buying plants
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Cost savings – Delphinium seeds are much more affordable than purchasing starter plants. Just a couple dollars will buy you hundreds of seeds.
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Wider selection – You’ll find many more varieties offered as seeds than what is available at most nurseries. From towering hybrids to dwarf types under 3 feet, seeds give you abundant options.
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Grow rare varieties – Specialty seed catalogs carry unique delphinium seeds you won’t be able to find anywhere else.
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Customize colors – By planting an assortment of seed varieties and colors together, you can create your own customized delphinium display.
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Seed saving – At the end of the season, collect ripe delphinium seed pods to save seeds for future plantings.
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Satisfaction of growing from seed – Starting these stately beauties yourself from tiny seeds is deeply rewarding.
For flower gardeners on a budget, starting delphiniums from seeds is clearly the way to go.
When to Sow Delphinium Seeds
Delphinium seeds need cool soil temperatures for the best germination rates. The ideal times for sowing are:
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Early spring indoors – Start seeds indoors 6-8 weeks before your last expected spring frost.
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Late summer/early fall – Sow seeds in late summer to early fall for germination the following spring.
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After last frost – Directly sow seeds into garden beds once the chance of frost has passed.
Proper timing prevents frustration and sets your seedlings up for success.
Step-by-Step Guide to Planting Delphinium Seeds
Follow this simple process for planting your delphinium seeds:
Indoor Seed Starting
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Fill seed starting trays or pots with seed starting mix. Moisten well before planting.
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Sow seeds 1/8 inch deep and 2-3 inches apart to allow room for growth.
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Cover trays with plastic wrap or a humidity dome to retain moisture.
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Maintain a soil temperature of 60-70°F until germination in 10-20 days. Move to a sunny window after sprouting.
Direct Outdoor Sowing
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Prepare seed beds enriched with compost in full sun locations. Rake smooth.
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Sow seeds 1/8 inch deep and 3-4 inches apart in rows or clusters where plants are to grow.
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Gently water seeded areas daily to keep moist, but not saturated.
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Thin seedlings to 10-12 inches apart once they are established.
Proper sowing depth and consistent moisture are vital for good germination rates when starting delphiniums from seeds.
Caring for Young Delphinium Seedlings
Once sprouted, delphinium seedlings need:
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Bright, indirect light to prevent scorching tender growth. Move outdoors gradually.
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Steady moisture – take care not to let seedlings dry out or become waterlogged.
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Good airflow from a fan helps prevent fungal disease issues.
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Liquid fertilizer every 2-3 weeks fuels rapid growth. Use formulas made for seedlings.
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Protection from slugs and snails who will devour the tender seedlings overnight. Copper tape or organic baits work well.
With attentive care, your seedlings will grow into stocky, healthy young plants ready for the garden.
Transplanting Delphinium Seedlings
Once delphinium seedlings have 4-6 true leaves, it’s time to transplant them into the garden. Follow this process:
Hardening Off
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Begin hardening off 1-2 weeks before transplanting seedlings outside.
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Move plants to a sheltered, shaded outdoor location for a few hours each day.
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Slowly increase the time spent outdoors over 7-10 days. Bring plants back indoors each night.
Transplanting
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Prepare garden beds enriched with compost in full sun locations.
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Space plants 10-12 inches apart in rows, clusters or groups.
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Dig holes slightly wider and deeper than each root ball.
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Carefully separate and transplant seedlings, keeping root balls intact.
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Backfill holes and gently firm soil. Water thoroughly after planting.
A proper hardening off period toughens up tender seedlings for garden planting success.
Ongoing Care for Delphiniums
To keep your delphiniums thriving for years to come:
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Water 1-2 inches per week from rainfall or irrigation. Increase in very hot weather.
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Stake taller varieties as they grow to prevent toppling. Use bamboo canes or metal plant stakes.
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Deadhead spent blooms to encourage repeat flowering.
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Cut back flower stems to the base after spring bloom period ends.
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Divide crowded clumps every 2-3 years in early spring.
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Mulch plants in fall with compost or shredded leaves for winter protection.
With attentive care and protection from slugs, delphiniums grown from seed will flourish, delivering their stunning spires year after year.
Troubleshooting Common Delphinium Problems
Here are some potential issues and solutions for delphiniums grown from seed:
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Poor or spotty germination – Ensure planting at proper depth and keep soils consistently moist. Use a humidity dome.
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Seedlings dying – Protect from slugs/snails. Avoid overwatering and improve airflow to prevent fungal disease.
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Spindly, weak growth – Give seedlings more light. Use a fan for air circulation. Fertilize regularly.
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Powdery mildew – Space/prune for better airflow. Water at base, not on leaves. Apply organic antifungal spray.
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Failure to flower – Some seed varieties are biennial and won’t bloom until second year. Be patient!
Catch problems early and adjust care methods to get struggling delphiniums back on track.
How to Save Delphinium Seeds
To save seeds for future plantings:
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Identify seed pods on spent flower stems once they turn brown.
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Harvest seed pods when they are dry and brittle. Store them in paper envelopes or bags.
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Crush pods to separate and collect seeds. Discard chaff.
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Let seeds further dry for 1-2 weeks. Store in a cool, dry location until planting.
With proper harvesting and storage, delphinium seeds remain viable for 2-3 years.
Final Tips for Growing Delphiniums from Seeds
Here are a few final tips for success with delphiniums grown from seed:
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Stratify seeds in the refrigerator for 7-14 days before planting to improve germination.
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Choose a seed starting mix formulated specifically for tiny seeds. Avoid heavy potting soils.
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Plant succession crops every 2 weeks for a longer harvest window.
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Control slugs and snails early to prevent destruction of seedlings.
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Stake plants when 12-18 inches tall to prevent damage by spring winds.
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Deadhead diligently to prolong bloom period.
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Avoid overhead watering to deter foliar diseases like mildew.
With proper planning and care, you can grow vibrant delphiniums from seeds for stunning vertical accents in your flower beds and borders.
How to Plant Delphinium
- For indoor sowing, mix the Delphinium seeds in with moistened soil or peat moss and place this in the refrigerator for a week
- After the period of cold, fill trays or peat pots with moistened seed starting soil
- Press the Delphinium seeds into the soil and lightly cover
- Ideal temperature for Delphiniums to germinate is 65 – 75F
- Keep the soil moist but not soggy
- Once there are seedlings, place them under grow lights for the best growing results
- Once outdoors temperatures are warming and no more frosts are expected, harden the Delphiniums off for 7 – 10 days
- If needed, at the time of transplanting, amend the soil with compost to improve the texture of the soil to make it lighter and drain better
- Or, in the early spring, work the soil to a depth of several inches
- Add compost to improve the soil
- Sow the Delphinium seeds on the surface and lightly cover with soil
- Keep the area constantly moist for germination
- Water well when the Delphinium plants are growing
- Provide stakes or other support if needed
- Mulch around the base of the plant to suppress weed growth and help to retain moisture
- After blooming, cut the spikes down to 4 or 5 inches in height and reduce watering
- Provide pesticide for slugs
Quick Facts About Delphinium
Delphiniums may be considered to be somewhat old-fashioned, but theres nothing like their majestic form and color to offer a beautiful display. The flowers are showy while the foliage is lacy and softens the background of the flower bed. They are great for cutting and can last 6 days or more in a vase, and bees and butterflies will enjoy visiting the gorgeous blooms.
Delphinium seeds do best with a cold treatment, so the seeds can be directly sowed outdoors in late winter/early spring when frosts are still expected. Or, after time in the refrigerator, start the seed indoors 6 – 8 weeks prior to the end of frost season.
Delphiniums do best in cold climates. They like full sun or partial shade and soil that drains well and is kept moist. Nutrient rich soil is very important.
How to Grow Delphinium Flowers From Seed – From Planting Seed to Flowering Delphinium Plant
FAQ
Is it hard to grow delphiniums from seed?
Delphinium can be one of the trickier seeds to germinate – I hear this from a lot of grower friends so I thought I’d share how I do it and things I’ve tried in the past. When I purchase delphinium seed (and larkspur, too) I immediately store in my freezer.
Do delphinium seeds need to be soaked before planting?
While not required, delphinium seeds can benefit from a special one to two week treatment called cold moist stratification prior to planting them.
What month should I plant delphinium seeds?
Growing Delphiniums from Seed
Start seeds indoors about eight weeks before the last frost of spring. Alternatively, sow seeds directly in flower beds in early summer.
Do delphinium seeds need light for germination?
Cover and Provide Light:
Cover the trays or pots with a clear plastic wrap or a seedling dome to create a mini-greenhouse effect. Place the trays in a warm location with indirect sunlight or use grow lights. Delphinium seeds need light to germinate, so do not place them in a dark area.
Do delphiniums reseed themselves?
Some varieties of delphinium will self seed, by snipping them off before they go to seed will keep them from spreading around the garden (unless that is your goal).
How do you plant Delphinium seeds?
To plant Delphinium seeds, place them on a wet coffee filter, fold it in half, and put it in a safe place. In about a week, you should see little roots emerging. Whether you’re sowing indoors or out, cover the seeds with about an eighth of an inch (one-third cm.) of soil.
Can delphiniums grow from seed?
Delphiniums grow easily from seed, however, not all types reseed. Start seed in winter or early spring or provide cold stratification by placing them in the refrigerator for several weeks. Gather seeds, small pots or a seed tray, a loose potting medium, compost, a plastic covering, and a spray bottle.
When should I start growing delphinium seedlings?
To get hardy delphinium plants ready to set out at the best time, start your seeds 6 to 8 weeks before your average last frost date. If you’re winter sowing, simply sow them when you sow your other seeds.
How long do Delphinium seeds take to grow?
Seedlings started to germinate within 17 days, and continue to do so. Delphinium seeds are among the list of flower seeds that are perfect to start indoors in winter. Sow delphinium seeds 6 to 8 weeks before last frost date. Delphinium seeds take three to four months or more to grow to maturity from planting. How Fast Do Delphiniums Grow From Seed?
Do delphiniums self propagate?
Do Delphiniums Self-Propagate? Delphiniums can reseed themselves. When the flowers of the delphinium plant fade and the seed pods dry out, the seeds inside can scatter to the ground and potentially grow new plants in the following growing season.
Can Delphinium seeds germinate without extra help?
Delphinium seeds are difficult to germinate without extra help. This method shows how to use your fridge to cold stratify delphinium seeds prior to sowing to ensure better germination rates. If you are new to growing delphiniums, also see the guide, How to Grow Delphiniums.