Indoor Guide for Planting Zinnia Seeds
For a burst of vibrant colour in your garden from midsummer until the first frosts, consider planting zinnias. Here's a guide on how to sow zinnia seeds, suitable for both beginners and experienced gardeners.
Timing is Key
Wait until the risk of frost has passed and soil temperatures are consistently warm, ideally around 70-75°F (21-24°C). In most US climate zones that warm by May-June, direct sowing without indoor starting is appropriate.
Choosing the Right Location
Select a sunny location with well-drained, moderately fertile soil. A sheltered site is ideal to protect your zinnias from cold winds.
Sowing the Seeds
Sow the seeds about 1/4 inch deep, barely covering them with soil. Space seeds or seedlings about 12 inches apart to allow for airflow and growth. To enhance germination, cover the seeds with a fine layer of vermiculite, horticultural sand, or more seed compost.
Caring for Your Zinnia Seeds
Keep the soil consistently moist until the seeds germinate, which typically takes 3 to 10 days. After plants are established, they tolerate some drought but should be watered during dry spells. Removing spent blooms encourages further flowering.
Growing Zinnias Indoors
If you'd like to start your zinnias indoors, place the pots or trays on a warm windowsill or in a heated propagator at 20-25°C. Prick out seedlings when they've formed two pairs of leaves, growing them on in their own pot.
Versatile and Beautiful
Zinnias are wonderfully versatile plants that can be used in borders and to fill gaps or transform patches of bare soil. They are also excellent cut flowers, adding a splash of colour to your home.
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[1] RHS, "How to Grow Zinnias" (2021) https://www.rhs.org.uk/advice/profile?PID=663
[2] Gardener's World, "How to Grow Zinnias" (2021) https://www.bbc.co.uk/gardening/howto/growzinnias
[4] HGTV, "How to Grow Zinnias" (2021) https://www.hgtv.com/design/outdoor-design/all-outdoor-projects/how-to-grow-zinnias
To achieve an alluring home-and-garden landscape from midsummer until the first frosts, consider planting zinnias in a sunny, sheltered, and well-drained location with moderately fertile soil. As the versatile zinnias can be used in borders and to fill gaps or transform patches of bare soil, they will add a vibrant splash of colour to your lifestyle and home.
