Colorado’s short growing season means dill should go into the ground after the last frost in late May. Finding the best time to plant dill in Colorado is key to a successful harvest. This guide covers everything you need to know about timing, soil prep, and care for dill in the Centennial State.
Dill is a cool-season herb that bolts quickly in heat. In Colorado, you have a narrow window to get it right. The key is to plant after the last frost but before summer heat peaks. Let’s break it down step by step.
Best Time To Plant Dill In Colorado
The exact date varies by elevation and microclimate. Generally, aim for late May to early June. This gives the soil time to warm up and avoids frost damage. Dill seeds germinate best when soil temps are between 60°F and 70°F.
In Denver and the Front Range, last frost usually happens around May 10–15. In higher elevations like the mountains, you might wait until June 1. Always check your local frost dates. A simple soil thermometer helps too.
Understanding Colorado’s Growing Zones
Colorado spans USDA zones 3 to 7. Lower elevations (zones 5–7) warm up faster. Higher zones (3–4) need more patience. Dill grows well in all zones if you time it right. For zone 5, plant in late May. For zone 3, wait until early June.
Here are some zone-specific planting windows:
- Zone 3–4: June 1–15
- Zone 5: May 20–June 5
- Zone 6–7: May 10–25
Soil Temperature Matters
Dill seeds won’t germinate in cold soil. If the ground is below 50°F, they rot. Use a soil thermometer to check. Insert it 2 inches deep. Wait until it reads at least 55°F consistently. This often aligns with late May.
To warm soil faster, use black plastic or row covers. Remove them once seedlings appear. This trick can shave off a week or two in cooler areas.
Preparing Your Garden For Dill
Dill likes well-drained soil with a pH between 5.5 and 6.5. Colorado soil is often alkaline. Add compost or peat moss to lower pH. Work in 2–3 inches of organic matter before planting.
Choose a sunny spot. Dill needs at least 6 hours of direct sunlight daily. Partial shade works in hot areas but reduces flavor. Avoid spots where carrots or fennel grew recently—they share pests.
Step-By-Step Planting Guide
Follow these steps for best results:
- Wait until after last frost. Check local weather.
- Prepare soil by tilling 6–8 inches deep. Remove rocks.
- Sow seeds 1/4 inch deep. Space 18 inches apart.
- Water gently after planting. Keep soil moist but not soggy.
- Thin seedlings to 12–18 inches apart when they reach 2 inches tall.
Dill doesn’t transplant well. Direct sowing is best. If you start indoors, use biodegradable pots. Transplant carefully when seedlings are 3–4 weeks old.
Succession Planting For Continuous Harvest
Colorado’s growing season is short, but you can extend your dill harvest. Plant new seeds every 2–3 weeks until mid-July. This ensures fresh leaves all summer. Stop planting after July 15—plants won’t mature before frost.
Succession planting works great for dill. Each batch takes about 60–70 days to flower. You get a steady supply of leaves and seeds. Just mark your calendar for each planting.
Dealing With Colorado’s Weather
Colorado weather is unpredictable. Late snow or hail can hit in May. Protect young dill with row covers or cloches. If a frost is forecast, cover plants overnight. Remove covers in the morning.
Heat waves in June can cause dill to bolt. Bolting means the plant flowers and goes to seed. Leaves become bitter. To delay bolting, provide afternoon shade. Water deeply during dry spells.
Caring For Dill Through The Season
Dill is low-maintenance but needs consistent care. Water 1–2 inches per week. Let soil dry slightly between waterings. Overwatering causes root rot. Mulch with straw to retain moisture and keep roots cool.
Fertilize lightly. Dill doesn’t need much. Apply a balanced 10-10-10 fertilizer once at planting. Avoid high-nitrogen formulas—they make leaves less flavorful. Compost tea works well as a side dressing.
Pest And Disease Management
Common pests include aphids, spider mites, and swallowtail caterpillars. Swallowtail caterpillars eat dill but are beneficial—they become butterflies. Leave a few plants for them. For aphids, spray with water or insecticidal soap.
Diseases are rare but include powdery mildew and root rot. Ensure good air circulation. Space plants properly. Avoid overhead watering. If mildew appears, remove affected leaves.
Harvesting Dill At The Right Time
Harvest leaves when plants are 6–8 inches tall. Pick outer leaves first. This encourages bushier growth. For seeds, wait until flower heads turn brown. Cut heads and dry them in a paper bag.
Fresh dill leaves are best used immediately. Store extras in the fridge wrapped in damp paper towels. Freeze or dry for long-term storage. Dill seeds keep for years in airtight containers.
Extending The Season With Fall Planting
You can plant dill again in late summer for a fall harvest. Sow seeds in early August. Plants will mature before the first frost. Use cold frames or row covers to protect them into October.
Fall dill often has better flavor because of cooler temperatures. Leaves are less likely to bolt. Just watch for early frosts. Cover plants if temps drop below 28°F.
Common Mistakes To Avoid
Many gardeners plant dill too early. Cold soil kills seeds. Wait until soil warms. Another mistake is overcrowding. Thin seedlings to 12 inches apart. Crowded plants compete for nutrients and water.
Don’t let dill dry out completely. Colorado’s low humidity dries soil fast. Check moisture daily. Mulch helps retain water. Also, avoid planting near fennel—they cross-pollinate and ruin flavor.
Dill Varieties For Colorado
Some dill varieties perform better in Colorado’s climate. Here are top choices:
- Bouquet: Classic variety, good for leaves and seeds.
- Fernleaf: Compact, slow to bolt, ideal for containers.
- Dukat: High leaf yield, strong flavor.
- Long Island Mammoth: Tall, productive, great for pickling.
Choose varieties that mature in 60–70 days. This fits Colorado’s growing window. Fernleaf is especially good for small spaces or high altitudes.
Frequently Asked Questions
Can I plant dill in April in Colorado?
Only if you use cold frames or indoor starts. Soil is usually too cold in April. Wait until May for best results.
How late can I plant dill in Colorado?
Plant no later than mid-July. Later plantings won’t mature before frost. For fall harvest, plant in early August.
Does dill need full sun in Colorado?
Yes, at least 6 hours daily. Partial shade works in hot areas but reduces growth. Full sun gives best flavor.
Can I grow dill in containers in Colorado?
Yes. Use pots at least 8 inches deep. Place in full sun. Water more often—containers dry out fast. Fernleaf variety works well.
Why is my dill bolting so fast?
Colorado heat causes bolting. Plant in late May, provide afternoon shade, and water consistently. Succession planting helps.
Final Tips For Success
Timing is everything for dill in Colorado. Stick to the late May window. Use a soil thermometer. Protect from late frosts and heat waves. With proper care, you’ll have fresh dill all summer.
Remember to thin seedlings. Water deeply but infrequently. Harvest leaves regularly to encourage growth. Save seeds for next year. Dill reseeds easily if you let some flowers go to seed.
Colorado’s unique climate requires attention, but dill is forgiving. Start small, learn your microclimate, and adjust each year. Before long, you’ll master the best time to plant dill in Colorado.
Happy gardening. Your dill will thrive with the right timing and care. Enjoy fresh dill in salads, pickles, and sauces all season long.