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Getting those towering, electric-blue flower spikes everyone stops to admire isn’t about luck. It starts with choosing the right genetics—live plants that hit the ground growing or seeds that actually carry the true delphinium heritage. Without that foundation, you’re fighting an uphill battle against weak stems and sparse blooms.
I’m Mohammad Maruf — the founder and writer behind Gardening Beyond. By comparing germination rates, root development claims, plant height potential, and pollinator attraction data across dozens of delphinium offerings, I separate the proven performers from the wishful thinking.
After examining owner reports and technical specs on live plants, bulbs, and seed packs, these are the five options that deliver real vertical drama for your borders. This guide to the best delphinium summer blues will help you pick the right starting point for your garden, whether you want instant impact or a rewarding grow-from-seed project.
How To Choose The Best Delphinium Summer Blues
Choosing delphiniums isn’t just about the bluest color on the package. You have to weigh the trade-off between immediate performance (live plants) and cheaper variety (seeds). The wrong choice means spending a whole season waiting for a flower spike that never reaches its promised height.
Live Plants vs. Seeds: The First-Year Reality
Live plants in 4-inch pots, like the Clovers Garden Black Knight, typically come with a developed root system and multiple stems. They’re ready to size up in your garden within weeks. Seeds require cold stratification, careful moisture management, and a full growing season to reach even 12 inches. If you want 6-foot spikes this summer, choose established plants. If you have patience and want mass planting on a budget, seeds are the better route.
Understanding the “Delphinium” Label
Not every seed packet labeled “Delphinium” is a true perennial delphinium. The Larkspur – Wild Delphinium Mixed Colors product is actually a larkspur (Consolida ajacis), an annual that behaves like a delphinium but doesn’t return reliably. True perennial delphiniums (Delphinium elatum) like the Blue Bell or Black Knight varieties regrow year after year in Zones 3-7. Check the botanical name, not just the common name.
Hardiness and Heat Tolerance
Delphiniums thrive in cool summers and moist, well-drained soil. If your region pushes past 85°F for weeks at a time, you need varieties with better heat tolerance or afternoon shade. The Baby Blue Eyes (Nemophila menziesii) is a California native that handles drier conditions, while the Electric Blue Spider Lily is actually a Lycoris, not a true delphinium—it blooms on a different schedule but offers striking blue-gray color.
Quick Comparison
On smaller screens, swipe sideways to see the full table.
| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| Clovers Garden Black Knight | Live Plant | Instant 6-foot spikes | 6 ft height, Zone 3-9 | Amazon |
| Blue Bell Delphinium Seeds | Seed Pack | Budget mass planting | 250 seeds, 4 ft height | Amazon |
| Electric Blue Spider Lily Bulb | Bulb | Unique blue-gray blooms | 1 bulb, Lycoris variety | Amazon |
| Larkspur – Wild Delphinium Mixed | Seed Pack | Cut flower filler | 400 seeds, annual, 3 ft | Amazon |
| 3000 Baby Blue Eyes | Seed Pack | Low-growing ground cover | 3000 seeds, 4-12 in | Amazon |
In‑Depth Reviews
1. Clovers Garden Delphinium Black Knight (Live Plants)
This is the highest-impact choice for anyone who wants towering deep-purple flower spikes this summer. You get two established plants, each 4 to 8 inches tall in 4-inch pots, with a root system that Clovers Garden markets as having “10x root development” compared to bare-root starts. The Black Knight variety is a true Delphinium elatum perennial hardy from Zone 3 through 9, meaning it will come back thicker each year if you cut the spent spikes.
The standout feature here is the instant scale. While seeds need a full season to produce a single flower, these plants hit the ground growing. Owners consistently report reaching 5 to 6 feet by midsummer with proper staking. The flower spikes are densely packed with blooms that attract bees, hummingbirds, and butterflies. The packaging is also notable—a 100% recyclable box with a printed Quick Start Planting Guide included.
At a premium price point for two plants, this is the most expensive option in the list. But for the gardener who wants a show-stopping vertical backdrop without waiting a year, it delivers immediate, reliable performance. The only catch: you need to plant them as soon as they arrive and provide consistent water in hot spells.
What works
- Strong root system gives fast establishment.
- True perennial that returns and expands each season.
- Massive 6-foot spikes with dense flower coverage.
What doesn’t
- Higher cost per plant compared to seed options.
- Requires immediate planting upon arrival.
- Needs staking to support tall spikes in wind.
2. Blue Bell Delphinium Seeds
If you’re willing to start from seed and have the patience for stratification, this 250-seed pack from Marde Ross & Company is the most cost-effective way to fill a border with light blue delphinium spires. The seeds are non-GMO and neonicotinoid-free, and the company has been a licensed California nursery since 1985, adding some pedigree to the genetics. The expected plant height is 4 feet—a bit shorter than the Black Knight, but still substantial for a cut-flower backdrop.
The seeds require surface sowing on bare soil with a light covering because they are sensitive to drying out. Cold stratification can improve germination rates, so don’t expect instant results. The bloom period runs from spring through summer, and the flowers are excellent for cutting or pressing. Being a bee attractor is a bonus for pollinator gardens.
At a mid-range price point for the seed category, you get 250 seeds—enough to experiment with different planting depths and stratification methods. The main downside is that first-year bloom is unlikely unless you start indoors very early. Plan for year two to see the full 4-foot height.
What works
- Generous 250-seed count for the price.
- Light blue blooms ideal for cutting and pressing.
- Non-GMO, neonicotinoid-free genetics.
What doesn’t
- First-year bloom is unlikely; requires patience.
- Seeds need careful moisture management to germinate.
- Cold stratification recommended but not mandatory.
3. Electric Blue Spider Lily Bulb
This isn’t a true delphinium, but if you crave that rare blue-gray flower color, this Lycoris variety delivers a different kind of drama. The Electric Blue Spider Lily blooms on bare stalks, producing spider-like petals in unusual blue-gray tones that appear suddenly without foliage. It’s a conversation piece that blooms early spring and goes dormant in summer, making it a surprise element in your garden.
The single bulb is beginner-friendly: plant it with proper drainage in full sun, water it during establishment, and it returns as a low-maintenance perennial. It’s also drought-tolerant once established and resistant to common pests. The bloom habit—flowers appearing before leaves—is unusual and creates a magical effect that experienced gardeners love.
At a slightly higher price than seed packs for just one bulb, the value proposition is different. You’re buying novelty and reliability, not quantity. It’s excellent for containers or mass planting if you buy multiple bulbs. The main drawback is that it’s a one-bulb purchase, so to create a real visual impact you’ll need to buy several.
What works
- Rare blue-gray color not found in typical delphiniums.
- Drought-tolerant and pest-resistant once established.
- Surprise blooming habit creates visual intrigue.
What doesn’t
- Single bulb; needs multiples for mass effect.
- Not a true delphinium or classic spike form.
- Goes dormant in summer, leaving bare ground.
4. Larkspur Seeds – Rocket Wild Delphinium Mixed Colors
This entry-level option offers 400 seeds at a low price and is technically a larkspur (Consolida ajacis), not a true perennial delphinium. While it’s marketed as “Wild Delphinium,” this is an annual that will not reliably return year after year. That said, it’s widely used by floral designers for its tall stems and mixed flower colors, reaching about 3 feet in height.
Sowing is straightforward: broadcast on bare soil, tamp down, and keep in full sun. It’s GMO-free and attracts pollinators, making it a decent filler for a cottage garden or cut-flower patch. Because it’s an annual, you’ll need to replant each spring, but the seed count is high enough that it’s cheap to refresh.
The main weakness is the lack of perennial reliability. If you want a self-sustaining delphinium patch, this won’t deliver. But if you just want a quick, cheap way to get colorful blue-purple spikes for bouquets this season, it does the job. Just manage expectations on rebloom.
What works
- Very low cost per seed with 400 seeds included.
- Easy direct-sow method with no stratification needed.
- Popular with florists for cut-flower quality.
What doesn’t
- Annual; must be replanted each year.
- Shorter 3-foot height compared to true delphiniums.
- Mixed colors reduce true-blue consistency.
5. 3000 Baby Blue Eyes Wildflower Seeds
This is the farthest outlier from the classic tall delphinium silhouette. Baby Blue Eyes (Nemophila menziesii) is a low-growing California native wildflower that maxes out at 12 inches. It produces masses of small, sky-blue flowers with white centers, perfect for filling gaps at the front of a border, in hanging baskets, or as a ground cover under taller delphiniums.
You get a whopping 3000 seeds, which is enough to cover a large area. They prefer full sun but tolerate partial shade, and they grow easily across the United States. The seeds are heirloom, open-pollinated stock from Marde Ross & Company. Being an annual, they will complete their life cycle in one season, but they often self-sow if conditions are right.
At a budget-friendly price for this massive seed count, it’s an unbeatable value for creating a blue carpet effect. But if you came looking for tall, spike-forming delphiniums, this isn’t it. It’s a complementary addition, not a replacement. Also, as an annual, it requires replanting or relies on self-seeding.
What works
- Extreme value with 3000 heirloom seeds.
- Perfect for low-growing blue ground cover or baskets.
- Easy to grow; tolerates some shade.
What doesn’t
- Not a delphinium; no tall flower spikes.
- Annual; requires replanting or self-seeding management.
- Short height makes it unsuitable as a backdrop plant.
Hardware & Specs Guide
Plant Height – The Core Metric
True delphiniums are all about vertical scale. The Clovers Garden Black Knight is rated at 6 feet, the Blue Bell Seeds at 4 feet, and the Larkspur at 3 feet. Height directly dictates staking needs and whether the plant functions as a backdrop or a mid-border feature. Taller varieties need strong support and are more susceptible to wind damage.
Perennial vs. Annual Lifespan
Only the Clovers Garden Black Knight and the Electric Blue Spider Lily are true perennials that return year after year (Zones 3-9 and 3-7 respectively). The Blue Bell Delphinium, Larkspur, and Baby Blue Eyes are either annuals or require careful reseeding management. This is the single most important spec for gardeners who want permanent structure, not seasonal filler.
FAQ
What is the difference between delphinium and larkspur seeds?
How long does it take for delphinium seeds to flower?
Can I grow delphiniums in hot summer climates?
Final Thoughts: The Verdict
For most gardeners, the best delphinium summer blues winner is the Clovers Garden Delphinium Black Knight because it gives you established live plants that produce towering 6-foot spikes in the same season. If you want to grow from seed on a budget, grab the Blue Bell Delphinium Seeds for 250 non-GMO seeds. And for a rare blue-gray novelty bloom with minimal fuss, nothing beats the Electric Blue Spider Lily Bulb.