Zinnia: Sow and Grow GuideUpdated 14 days ago

Zinnias are easy-to-grow, colorful annuals that thrive in warm weather. Here’s a concise guide to successfully sowing and growing zinnias.

When to Sow

Zinnias should be sown outdoors after the last frost when the soil is warm, above 60°F. Alternatively, you can start seeds indoors 4-6 weeks before the last frost to get a head start.

Outdoor Sowing

Select a sunny spot with well-drained soil. Prepare the soil by loosening it, then sow seeds 1/4 inch deep, spaced 9-12 inches apart. Lightly cover with soil and water gently. Maintain consistent moisture until seeds germinate in about 5-7 days.

Indoor Sowing

For indoor sowing, use seed trays with a seed-starting mix. Sow seeds 1/4 inch deep and keep the soil moist. Provide plenty of light, using a grow light if needed. Harden off seedlings by gradually introducing them to outdoor conditions before transplanting.

Care and Maintenance

Zinnias need full sun and regular watering, especially during dry periods. Ensure soil drains well to avoid root rot. Deadhead spent blooms to encourage continuous flowering. A light, balanced fertilizer can be applied during the growing season if the soil lacks nutrients.

Pests and Diseases

Zinnias are generally low-maintenance but can attract aphids, spider mites, and whiteflies, which can be managed with insecticidal soap. To prevent powdery mildew, space plants well for good air circulation and water at the base to keep foliage dry.

Harvesting

Zinnias make excellent cut flowers. Harvest in the morning by cutting stems above a pair of leaves, removing any foliage below the waterline in the vase.

Garden Use

Zinnias attract pollinators and are great for borders, beds, and containers. They’re also good companion plants for vegetables like tomatoes, as they attract beneficial insects.

For further details, visit the full guide on the Botanical Interests Blog.