Growing Zinnias From Seed

Zinnias are as attractive in the garden as they are accommodating.  They are relatively easy to grow from seed, and transplant into the garden with minimal hassle.  I always think of zinnias as a staple home-grown flower…it isn’t the kind of flower that you’d typically think to purchase at a florist.  If I am going to have cut zinnias, I am going to grow them.   Thankfully, with all the new hybrid varieties these days, I have more bloom options than ever before.  New varieties offer double blooms, dahlia-like flowers, and even multicolored flowers.  So, no, I won’t have to grow my Grandmother’s zinnias. (Although with an heirloom variety, I certainly could.)

pink zinnia

A closeup of a pink zinnia in full bloom

How to Start Zinnia Seeds

You can start zinnia seeds either indoors or directly in the ground.   If you are willing to start a few seeds indoors, you can enjoy blooms much sooner.  Plan to start your seeds in small containers with drain holes, or in a seed starting flat, about five weeks before you last frost date.  If you make zinnia seeds happy, they will sprout in the greatest numbers.  When it comes to zinnias — the more the merrier, right?  So keep your germinating seeds stored in a dark place at about 70 degrees Fahrenheit.   Overwatering zinnia seeds will cause them to rot in the soil mix.  So I prefer to keep my zinnia seeds slightly drier than I do most other seeds.  I’ll water them right after I put them in a seed starting mix, then it’s into the closet they go.  I’ll pull them out every few days and give them a little water, then right back in.

Zinnia Seeds

Cut and Come Again zinnia seeds

Zinnias usually sprout within a week.  Once they do, place your seedlings in a sunny window or under grow lights for the next month.  Young zinnias do not need much water, so try to water them only once every four days.  You can also use a wet mat under fiber seed pots and water them from underneath.

Even if your garden is off to a late start this year, fear not: there is still time for zinnias.  Unlike larkspur (which can take four months to bloom), zinnias are in full flower after two and a half months.  It’s also fun to plant different zinnias throughout the summer.  Your best option if you get a late start is to sow them directly into the garden.   Scatter your seeds where you want the flowers to grow, and cover them with compost.  Once the seeds have germinated and grown remove any extra plants leaving one healthy plant every foot and a half or so.

Planting Zinnias In Your Garden

Rule number one – FULL SUN.  Zinnias need full sun in order to bloom.  The sunnier your garden, the more blooms you will have all summer long.  Rule number two – GOOD SOIL.  If you plant your zinnias in high quality soil, you will get high quality flowers.  Good soil means the soil is loose enough for roots to grow deep.  It also means soil that is rich in organic material.

Butterfly on zinnia

Zinnias attract butterflies all summer

Once you meet these two conditions, zinnias can pretty much fend for themselves.  If there are long hot spells during the summer, then be sure to give them some extra water.  Cutting blooms will only cause the zinnia plant to produce more flowers.

There are two small cautions for zinnias in the garden.  If there is a prolonged period of rain, then zinnias may be prone to powdery mildew.  A sticky, cotton-like mold will grow on the leaves and harm the plant.  The other word of caution is for areas that have long, hot summers, and don’t experience frost until November: you may have to add a second planting of zinnias, since the first planting is likely to be spent by late August.  Keep in mind that when zinnia plants are exhausted, they will quickly die back.  You have done nothing wrong.   In most climates, the only thing you can do is bid them farewell and get ready for next year’s planting.


Zinnia Quick Reference Guide

Life Span -Annual, in climates that have very mild winters may act like a perennial
Propagation -Seed
Bloom Season -Summer, early fall
Flower Qualities -Red, orange, yellow, green, purple, white, bicolored-Many varieties have double blooms-Flower size ranges from 1”-6”
Garden Location -Full sun at least six hours-12” of space between plants-May not grow well indoors

-Growing zones 3-10

Soil Preference -pH Range 5.5 – 7.5-Well drained soil-Too much fertilizer may cause plants to grow large and bushy without

producing many blooms

Uses -Containers-Cutting garden-Dwarf varieties work as a bedding flower

-Attracts butterflies and other beneficial insects


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