How to Grow Zinnia
Zinnia At a Glance
Difficulty
Easy
Category
Flower
Sun Exposure
Full Sun
Frost Tolerance
Frost Tender
Cold Hardiness
Survives to 2°C
Plant Family
Asteraceae
Growing Season
Warm Season
Plant Lifecycle
Annual
How to Start It
★ Recommended for beginners
Zinnias love heat, so sow them about 1 week after your last spring frost, once the soil is warm. Sow 2 seeds 0.5 cm deep every 20 cm and cover them. They sprout fast, in 5 to 10 days: keep the stronger seedling at each spot and snip off the other.
Zinnias are one of the easiest flowers to grow from seed and bloom in about 60 days. They are a cut flower that loves to be cut: the more stems you take, the more flowers they make, right up to frost. Butterflies and bees visit them all summer.
When To Start
First chance to plant
7 Days After Last Frost
Last chance to plant
30 Days Before First Frost
When should you plant Zinnia?
Your planting dates depend on your local climate. Sign up and add your location to unlock personalized dates.
Your Zinnia Planting Window
Start planting
May 15, 2026
Last chance
Sep 10, 2026
Your Zinnia Calendar
Set your location to turn these into exact dates and reminders.
Sow zinnia seeds outdoors now that the soil is warm
1 week after your last frost· every year
Cut zinnias often, more cutting means more flowers
60 days after your last frost· every year· optional
Did you water your zinnia seedlings today? Keep the top of the soil damp until they are up and growing.
About 1 days after you plant it
Your zinnias are growing fast! Pinch the top once plants are about 20 cm tall for more blooms.
About 30 days after you plant it
Hi there! Cut zinnia flowers often and the plants keep making more.
About 50 days after you plant it
Picking time may be here: check your zinnia.
About 60 days after you plant it
The Journey Ahead
Zinnia's Lifecycle
Seedling
Mature Plant
Seed Production
Step 2
Planting & Sprouting
Expect sprouts in 5–10 days
Growing Tips
- 1Give zinnias full sun, at least 6 to 8 hours a day, and they bloom nonstop.
- 2They grow well in average soil with some compost mixed in.
- 3Water deeply at the base about once a week, and keep the leaves dry.
- 4Feed with compost tea once a month after the flowers start.
- 5When the plants are about 20 cm tall, pinch off the top just above a pair of leaves so they branch into many long stems.
- 6Powdery mildew (a white dust on the leaves) is their main problem, so space them well for airflow and water in the morning, and pick Japanese beetles off by hand into a cup of soapy water.
Seedling Phase
Step 3
Growth & Maturity
~60
Days to Maturity
75 cm
Mature Height
30 cm
Mature Width
Pests to Watch For
Diseases to Watch For
Mature Plant
Step 4
Harvesting
Harvest Window
30 days
When to Pick
Harvest flowers at full color
How to Harvest
- 1Cut zinnias when the flower is fully open and the stem is firm: hold the stem about 20 cm below the bloom and give it a gentle shake.
- 2If the flower head stays upright, it is ready, and if it flops, wait a few days.
- 3Cut long stems just above a pair of leaves, and new stems will grow from there.
- 4Put them straight into cool water, where they last about a week.
- 5Keep cutting or snipping off faded flowers all summer for more blooms.
Step 5
Saving Seeds
How to Save Seeds
Zinnias are pollinated by bees and cross with other zinnias, so seed from mixed colours grows into a fun surprise mix, and hybrid F1 seeds will not grow true. Pick a few of your best flowers and let them dry right on the plant until the petals and centre are brown and crisp. Pull the head apart to find the arrow-shaped seeds at the base of the petals. Keep the plump ones and let them dry a few more days on a plate. Store them in a labelled envelope somewhere cool, dark and dry, where they keep for a few years.
Seed Production
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