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How to Grow Beautiful Zinnias

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Zinnias are a classic annual flower that is as popular today as it was in your grandmother’s day. The tall stately stems bear large colorful flowers that attract hummingbirds and butterflies. These beautiful plants will produce blooms all summer and they are long-lasting when used as cut flowers.

With all these quality characteristics, it’s easy to see why zinnias are so popular in home gardens.

Use these tips and plant some zinnias this spring.

When To Grow Zinnias

Zinnia blooms, no matter which variety, are best grown in the warmer months of spring and summer.

Wait until all danger of frost has passed in the spring before planting zinnia seeds or planting plants purchased at a reputable nursery. Ideally, the soil will also be warmed up.

Zinnias do not tolerate frost, so be sure to also check Almanac.com to be sure that your last average frost date has passed before planting zinnias.

zinnia in the garden
Zinnia bloom in the garden

Where to Grow Zinnias

Select a growing location that is in full sun and has well-draining soil. Add 2-inches of compost to the soil and work in down to 4-inches deep to help ensure the soil drains well and to provide long-lasting nutrients for the zinnias.

If planting zinnias in the same place you grew them last year, chances are they could have dropped seed. If you did let last year’s zinnias dry out, then you may have volunteers popping up.

How to Plant Zinnias

  • Grab a packet of zinnia seeds or use your seeds you saved from last year
  • Scatter a few seeds on top of the compost-prepared soil and cover with 1/4 of soil.
  • Water gently
  • Zinnia seeds will germinate in 5-days.
  • Thin plants to 6-inches apart after germination. 

Zinnias are adaptable to most soil conditions except heavy clay or soggy soil. These classic flowers do not like their feet to remain wet, so for best results plant the flowers in well-draining soil.

How to Care for Zinnia Plants

Lazy gardener? Lucky you! Zinnias are easy-care plants that require minimal maintenance.

Watering– only water zinnias during times of prolonged drought or if the plants begin to wilt. Do not overwater.

Pruning– Remove spent blooms to encourage more zinnia blooms. You can also cut the blooms along with 6-8 inches of stem to use indoors in flower arrangements. Cutting blooms and dead heading with both encourage growth and flower production in the zinnia plants. (Want to grow a cutting garden this year? Check out this full post about how to plan a cutting garden.)

Fertilizing– Zinnias do not need to be fed during their lifetime but you can apply a balanced fertilizer in mid-summer as a side-dressing.

Common Zinnia Problems

Zinnias are prone to develop powdery mildew if they are being grown too close together. These plants need plenty of air circulation to remain healthy and productive. Thin mature plants at the first sign of powdery mildew to improve airflow around the plants.

Leaf Spot is also a common ailment in zinnia plants. This appears as small brown spots covering the leaves with yellow circles around each spot. There are several forms of leaf spot that can affect zinnias, so keep your eyes peeled for this bacterial disease.

Aphids can also be a nuisance for zinnias. These tiny bugs use their sucking mouth parts to leach nutrients from the plant. There are several natural ways to get rid of aphids, so be sure to check these out.

aphids on a flower stem
aphids on a flower stem

Pruning and Cutting Zinnias

Zinnias create long-lasting cut flowers and regular pruning each plant will produce multiple blooms during the summer.

  • The first pruning is to force the plant to produce lateral branches instead of just one tall stem. 
  • When the plant is about 10-12 inches tall and has developed a couple of sets of leaves, cut it down to 4-inches tall or the top two sets of leaves with a sharp pair of pruners. 
  • This is the only severe pruning the plant will need. Cut off the faded flowers during the growing season to encourage that plant to produce more zinnia blooms.

At the end of the summer or beginning of fall, allow a few zinnia blooms (or more) to completely dry out on the plant. This will give you plenty of dry blooms perfect to use for saving zinnia seeds.

See my full tutorial here on how to save zinnia seeds. I’d love to know what types of zinnias you’ll be growing this year!

a new garden seedling ready for planting
When to Start Garden Seeds
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