Updated: Mar 2
Reasons to grow zinnias include beautifying your yard, producing lovely cut flower bouquets, and caring for bees and butterflies. Zinnias are native to North America, growing in the wild from Texas through Mexico, but provide pollen and nectar as food for native species of insects that are found throughout North America. I have observed a myriad variety of bees and butterflies enjoying our zinnias here at Sterling Organic Farm, as shown in the photos below. Not only do these flowers benefit the bees, but also they can beautify your world. Zinnia flowers left in the garden to fully open and feed the bees can then be cut and enjoyed in your home. Zinnias are one of the few flowers that have their longest possible life in the vase as a cut flower when they are harvested fully open. This gives both you, the bees, and the butterflies plenty of time to be nourished by the beauty of these flowers! Cutting the zinnias keeps them flowering all summer long. Zinnias are generous. The more you cut, the more they bloom. The cut end of each plant then sends up multiple blooms, meaning that cutting off one flower can cause four more to grow. Zinnias also come in a bounteous rainbow of colors, with blue being the only shade not represented. In the 2019 growing season, my one of my top favorite crops to grow was the beautiful row of zinnias in our hoop house.
This is the second post in a series I am doing about plants you can grow to help pollinators. The first plant profiled was milkweed, which you can read about here. Growing these plants in our yards helps to make human life on earth more sustainable by providing a home for these vital members of our ecosystems.
Bees and butterflies feast on zinnias at Sterling Organic Farm in the photos below.
How to Grow Zinnias
In this post, I will present four ways to grow zinnias. Winter sowing can be done between December 22 and April 30, here in Connecticut and in other locations with similar seasons and climate. Starting seeds indoors is best done four to six weeks before the last frost, which means early to mid-April for our climate. Direct sowing can be done from last frost through 90 days before first frost. Here in CT, that means we can direct sow zinnias late May through early July. Lastly I will discuss how we grow a fall crop of zinnias in the hoop house here on the farm, and the special benefits this provides to migrating monarch butterflies.
Zinnias will germinate when the soil is hot, at least 75 degrees Fahrenheit. Don't let this fact stop you from sowing the seeds in the depths of winter! You will have less garden work to do in the spring by using winter sowing, and the zinnia seeds will wait until conditions are perfect to germinate. This means that you might get blooms slightly later by using winter sowing than if you start your seeds indoors. You will need a clear or translucent plastic container that can hold at least three inches of soil and still have room in the top of the plant to grow upwards. Milk jugs are an excellent container, as are three liter soda bottles, plastic vinegar jugs, and plastic kitty litter tubs. Cut the container nearly in half, leaving one inch attached as a hinge. Punch holes in the bottom of the container for drainage. Fill the bottom half of the container with potting soil, and plant the zinnia seeds one half inch deep into the soil. Seal the containers closed with duct tape, and leave outside all winter. Make sure to take the cap off of the container to allow rain and snow in, and to let excess heat out on sunny days. Check occasionally to make sure they are not too dried out, and add water as needed. Transplant your zinnia plants eight inches apart in the garden once all danger of frost is past. Tall varieties such as the benarys giant zinnias that we grow on our farm will look best in the back of garden beds. Plant on the south facing side of your house to help prolong the blooms into the early fall. Zinnias enjoy full sun.
Winter sowing is used for many crops here at Sterling Organic Farm in eastern CT.
Zinnia seeds like hot temperatures to germinate, and zinnia seedlings will not tolerate a frost. They are from a warm climate. Start your zinnias indoors 4-6 weeks before the last frost. Use a special seed starting tray, or any plastic container that is at least 2 inches deep, such as a plastic container from getting takeout food, or yogurt tubs. Make sure your container has holes in the bottom (or poke them as needed) to allow water to drain out the bottom. Fill your tray with damp seed starting mix. Plant the zinnia seeds 1 inch apart, and 1/2 inch deep. Put your tray on a seed-starting heat mat set to 75 degrees, or put it in a warm place, such as on top of your refrigerator until the seeds germinate, which should happen in 1-4 days. Place your zinnia seedlings right up against a south facing window that is not shaded by any trees. Alternatively, use LED shop lights (these cost about $20 each at home depot for a four foot light) and place your lights five inches above the tops of the newly germinated zinnia seedlings. Transplant to the garden after the last frost, eight inches apart.
Starting seeds indoors at Sterling Organic Farm in Oneco, CT. We use our south facing sun porch. The trays closest to the windows get by on natural sunlight, while the trays further from the window are under inexpensive LED shop lights held up by cinder blocks.
Certain varieties of the humble zinnia that come in white, ivory and blush shades can even be used in wedding flowers. I plan to use our zinnias in my wedding flowers for my own wedding this August, and one of the brides I have met with for 2020 has requested white zinnias in her bouquet. Zinnias hold up very well in the heat if you are having a summer outdoor wedding. They won't wilt in the sun. If you are a florist, be sure not to put them in the cooler, as this will make them wilt. Keep reading to find out how easy it is to direct sow zinnias in your garden!
Zinnias are one of the few crops that we direct sow on our farm. Our farm had been somewhat neglected for a few years when we bought it, due to the previous farmer's health challenges. The soil is chock full of weed seeds, and usually weeds come up faster than the seeds we direct sow. Zinnias beat the weeds. They often germinate just one to three days after being planted. When sown in the early summer into nice hot soil, they germinate in just one day. Poke holes 1/2 inch deep, eight inches apart in your garden. Plant two seeds per hole, in case one doesn't germinate. When the zinnia seedlings have four true leaves, thin your seedlings to one plant every eight inches apart.
Hoop House Fall Zinnias
In late July 2019, my sister visited the farm and helped me out by planting zinnia seeds in one of our hoop houses. She sowed the seeds directly in the ground, and two days later the little seedlings poked up their tiny round green leaves. On September 18, the glorious first flush of zinnia flowers was in full effect. The zinnias lasted through several light frosts due to being in the hoop house. We would open up the sides of the hoop house during the day to provide air circulation and prevent powdery mildew, then close the house at night to keep the heat inside. In October, when few other flowers were blooming, migrating monarch butterflies would gather in our hoop house to warm up and feast on the nectar of the zinnias. We had zinnias blooming until the night of October 31, when the first hard frost took them out, despite the protection of the hoop house.
Zinnias that my sister sowed having their first flush of flowers in the hoop house. I cut off all the flowers every Wednesday to make bouquets to sell to the Fiddleheads Food Coop. Without fail, the zinnias would have new blooms the next Wednesday, despite cutting them all off just seven days before.
Migrating monarch butterflies are important pollinators that enjoy the zinnias in our hoop house.
Other ways to support the pollinators
We know that not everyone has space in their yard to grow zinnias, nor does everyone have the time or the ability to grow a garden. As farmers, we know firsthand how hard it is to grow things! Fortunately, there are other ways you can ensure that more flowers will be planted to help the pollinators. Support your local flower farmers. Consider picking up a bouquet the next time you attend a farmers market, or use a local farm to provide flowers for your wedding or other special event. The Slow Flowers website is a great way to find a flower farmer near you. If you are in Foster, RI, Sterling, CT or Narragansett, RI consider purchasing our flower share where you get a bouquet of flowers from our farm each week. For every share we sell, we plant more flowers that help the pollinators, like our zinnias. Click here to learn more about the flower share. If you are getting married in Southern New England, consider having us grow and arrange your wedding flowers. You can also shop our merchandise. All of the profits from our merchandise is being used to restore our farm to working condition, such as repairs to our greenhouses and a new tractor. Below are pictures of our merchandise that feature pictures of our zinnia flowers.