If you’re a gardener in zone 6, timing is everything for a spectacular spring show. Knowing exactly when to plant larkspur seeds in zone 6 is the key to success.
These cottage-garden favorites, with their tall spires of blue, pink, white, and purple, are surprisingly easy to grow from seed. They just need a little nudge from the cold to germinate well. This guide gives you the simple schedule and steps for optimal spring blooms.
When to Plant Larkspur Seeds in Zone 6
For zone 6 gardeners, you have two perfect planting windows: fall and very early spring. Fall planting is often the most successful and highly recommended.
Here’s your simple seasonal schedule:
- Fall Planting: Sow seeds directly in the garden from late September through mid-October. The goal is to get the seeds in the ground after summer heat fades but before the ground freezes solid. This allows the seeds to experience the natural cold, moist conditions they need to break dormancy.
- Early Spring Planting: Sow seeds as soon as the soil can be worked in late winter or very early spring. This often means late February to March, even if there’s still a chance of frost. You can also refrigerate seeds for 1-2 weeks before spring sowing to mimic winter cold.
Why Larkspur Needs Cold (The Science of Stratification)
Larkspur seeds have a built-in survival mechanism. They contain compounds that prevent germination until they’ve experienced a period of cold and moisture. This ensures they don’t sprout in a warm autumn only to be killed by winter.
This process is called cold stratification. In nature, winter provides it. In your garden, you can let nature do the work by fall planting, or you can simulate it in your refrigerator for spring sowing.
Choosing the Perfect Spot in Your Garden
Larkspur are not fussy, but they do have preferences. Getting the location right means healthier plants and more flowers.
- Sunlight: Full sun is best—at least 6 to 8 hours of direct sun daily. They can tolerate very light afternoon shade, especially in hotter parts of zone 6.
- Soil: Well-draining soil is absolutely critical. Larkspur will rot in heavy, soggy clay. If your soil is poor, amend it with compost to improve texture and fertility.
- Space: These plants can grow 2 to 4 feet tall. Give them room for air circulation to prevent disease. Space seeds or seedlings about 10 to 12 inches apart.
Step-by-Step: How to Plant Your Larkspur Seeds
Follow these simple steps for a great start, whether planting in fall or spring.
1. Preparing the Soil
Clear the planting area of weeds and debris. Loosen the soil to a depth of about 8-12 inches. Mix in a 2-inch layer of compost if needed. Rake the surface smooth.
2. Sowing the Seeds Correctly
Larkspur seeds need darkness to germinate. Don’t just scatter them on top!
- Sow seeds about 1/4 inch deep. You can make a shallow furrow with a stick or your finger.
- Place seeds 2 inches apart in the row. You’ll thin them later.
- Cover the seeds lightly with soil and gently firm it down with your hand.
3. Watering After Planting
Water the area gently but thoroughly with a fine spray. You want the soil to be moist, not soggy. Keep the soil consistently moist until seedlings emerge, which can take 14-30 days for fall plantings (they’ll wait until spring) or 2-3 weeks for spring plantings.
Caring for Your Growing Larkspur
Once they’re up, larkspur need minimal care. Here’s what to do.
Thinning Seedlings
When seedlings are a few inches tall and have their first set of true leaves, it’s time to thin. Choose the strongest ones and snip the others at soil level. Final spacing should be 10-12 inches. This gives each plant plenty of room and air flow.
Watering and Feeding
Water young plants regularly until they’re established. Mature larkspur are somewhat drought-tolerant. Water deeply during prolonged dry spells. A light application of a balanced, slow-release fertilizer in early spring is usually plenty, especially if you have good soil.
Supporting Tall Blooms
The tall flower spikes can get top-heavy, especially after rain. Prevent flopping by providing support early. Use grow-through grid supports or simple stakes and twine when plants are about 12 inches tall.
Encouraging More Blooms and Managing Pests
To keep the show going, deadhead spent flower spikes by cutting them back to a side shoot or leaf. This often encourages a second, smaller flush of blooms. At the end of the season, you can let some flowers go to seed if you want them to self-sow.
Watch for slugs and snails on young seedlings. Use organic bait if needed. Aphids can sometimes appear; a strong spray of water usually knocks them off. Good spacing helps prevent powdery mildew.
The Self-Sowing Secret for a Perennial Show
One of the joys of larkspur is its ability to self-sow. If you let the last flowers of the season mature and drop seed, you’ll likely get new seedlings the following fall and spring. These volunteer plants are often even stronger. Just remeber to thin them out to prevent overcrowding.
Common Mistakes to Avoid
- Planting too deep: Seeds need darkness, but burying them more than 1/4 inch can prevent germination.
- Planting in soggy soil: This is the fastest way to lose seeds or seedlings to rot.
- Skipping thinning: Crowded plants are weak, prone to disease, and produce fewer flowers.
- Waiting too long in spring: If you miss the early spring window and plant in warm soil, germination rates will be very low.
FAQ: Your Larkspur Questions Answered
Can I start larkspur seeds indoors?
It’s possible but tricky. They dislike root disturbance. If you try, use deep cell trays and transplant very carefully when young. Direct sowing is usually more succesful.
What’s the difference between larkspur and delphinium?
They are closely related. Larkspur (Consolida) are annuals with finely cut leaves and smaller flower spikes. Delphiniums are perennials with larger, palmate leaves. Both are beautiful, but larkspur is often easier in zone 6.
My seeds didn’t come up. What happened?
The most common reasons are: soil was too warm (lack of cold stratification), seeds were planted too deep, or the soil dried out during germination. Try again in the fall for best results.
Will larkspur bloom all summer?
No, they are cool-season bloomers. In zone 6, they peak in late spring to early summer. Heat will cause them to decline. You can succession plant every two weeks in early spring for a longer bloom period, but they will finish as summer heat arrives.
Are larkspur plants deer-resistant?
Yes, they are generally considered deer-resistant due to their toxicity. All parts of the plant are poisonous if ingested, so it’s best to plant them away from areas where children or pets play.
By following this simple timing guide—sowing in fall or very early spring—you’ll be rewarded with a stunning, graceful display of color that marks the true arrival of spring in your zone 6 garden. The tall spires look wonderful cutting gardens, mixed borders, and cottage-style plantings, providing height and a soft, romantic feel.