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How to Start Zinnia Seeds Indoors

By Traci Joy ; Updated September 21, 2017
Zinnias

Zinnias are annual flowers that come in many colors and styles, including single- and double-petaled flower heads. Depending upon the type of zinnias, they can grow from 8 inches to 4 feet tall, so before selecting zinnia seed, consider where they will be planted. Dwarf zinnias do great in pots, while the taller zinnias add a stunning background to any flower bed. No matter which type of zinnia you choose, to get a head start on the blooming season, start the seeds indoors.

Start zinnia seeds four to six weeks before the last expected frost.

Plant in peat pots that are 2 to 3 inches tall. Starting seeds in peat pots will do away with the need to re-pot as they grow.

Fill the pots with a seed-starter potting soil mix, leaving 1 inch of room at the top. Place the peat pots in a large seed tray and water until the soil is moist but not drenched.

Place three seeds on the soil and cover with 1/2 inch of soil mix. Moisten the top soil with a mist of water from a spray bottle.

Cover the pots with a large sheet of plastic wrap. Place the tray in a warm location with bright light. Germination should begin within six to 10 days.

Remove the plastic wrap. Place the seedlings in a bright, sunny window.

Continue to keep the soil moist, but water the plants from the bottom by keeping water in the seed tray. Check the soil inside the pot for moisture with your fingers.

Thin the number of seedlings in the pot by snipping the weaker ones off at the base.

Plant in the garden bed when the danger of frost has passed. Plant the peat pots directly into the ground, if desired, as they are biodegradable, or gently peel the pot away from the roots before planting.

 

Things You Will Need

  • Seed tray
  • 2- to 3-inch peat pots
  • Seed-starter potting soil mix
  • Plastic wrap

Tips

  • Zinnia seeds can also be easily sown directly into the garden bed once the soil has warmed and danger of frost has passed. Plant the seeds in a row, 1/2 inch under the soil. Water, and when seedlings emerge, thin them out to the desired spacing.
  • Zinnias prefer full sun, and the National Garden Bureau says they will do well in any soil type as long as it has good drainage.

Warnings

  • Plant zinnias where they will receive afternoon shade in hot, desert areas.
  • If the window where the zennias grow isn't sunny enough, they will be tall and lanky from stretching toward the light.

About the Author

 

A certified nutritionist who majored in health, fitness and nutrition, Traci Vandermark has been writing articles in her specialty fields since 1998. Her articles have appeared both online and in print for publications such as Simple Abundance, "Catskill Country Magazine," "Birds and Blooms," "Cappers" and "Country Discoveries."