If you want to add a pop of color to your summer garden, you can’t go wrong with zinnias! These easy-to-grow flowers come in a rainbow of colors and all different sizes and shapes. Here’s a guide to help you choose the right zinnia varieties for your garden and grow them successfully.
Types and Varieties of Zinnias
Zinnias are native to the grasslands of Mexico, where a diversity of wild species thrive in hot, low-water conditions. European plant breeders took an interest in zinnias in the early 1800s, and over the next century, created the kaleidoscope of different petal shapes, colors, and sizes we see today in domesticated varieties.
Zinnias come in three basic categories of petal types:
- Single-Flowered varieties like Persian Carpet have petals arranged in a single row around the center, similar to a typical daisy.
- Semi-Double-Flowered varieties like State Fair Mix have petals arranged in two or more rows, giving the flower a more full, ruffled appearance, but the center is still visible.
- Double-Flowered varieties like Lilliput Mix have petals arranged in multiple rows overlapping each other so that the center of the flower is hidden within the petals.
Zinnia blossoms come in a range of shapes! Cactus-flowered types have petals that roll and twist into pointed, quill-like forms. Beehive types like Lilliput Mix have tall mounds of petals, while button types, such as Thumbelina Mix are flattened, and globe types like Cherry Queen have big, rounded, show-stopping blossoms.
The mature height of your zinnia plants is an important factor to consider when choosing varieties, and deciding where to plant them. Long-stemmed types like Cherry Queen, California Giants, State Fair, or Cactus Flowered Mix grow 2-3 feet tall, and are great for the back of a flower bed where they won’t shade out other plants. Low-growing types like Persian Carpet, Thumbelina or Lilliput Mix are better for the edges of beds, where they can shine.
Planting and Growing Zinnias from Seeds
Zinnias are one of the easiest flowers to grow from seed. In fact, they are very sensitive to transplant shock, so it’s best to direct-seed them in your garden rather than purchasing plant starts.
When to Plant Zinnias
Zinnias should be seeded in late spring. They are not at all frost-tolerant, so wait until all danger of frost has passed before planting. Zinnias are fast-growing, so most growers will have plenty of warm growing season to enjoy blooms from direct-seeded plantings.
Choose and Prepare a Planting Site
Make sure to choose a location with full sun for your zinnias. Zinnias are fairly tolerant of a range of soil conditions, but they’ll grow more vigorously in soil that is rich in organic matter and well-drained. Give your flowers a boost by amending the bed with an inch or two of compost before planting.
How to Plant Zinnia Seeds
Typically, zinnia seeds should be sown about ¼ inch deep and 4-6 inches apart, and then thinned to about one foot between plants. Check the instructions on your seed packet, since different varieties have different growth habits and may need more or less space. Seedlings should start to appear in 4-7 days, and the plants will begin blooming within two months.
Maintaining Zinnia Flowers
Zinnias only need moderate amounts of moisture, so don’t overwater. As blooms open and then wilt, clip them off the plants to encourage more blooming (this is called “deadheading.”) If you started with compost-amended soil, your zinnias probably won’t need any further fertilization during the season. You really can almost just plant them and forget about them, which is what makes them such a great addition to any garden!
Pest & Disease Prevention
As with many other plants, it’s best to water your zinnias from the base and in the morning, to minimize wet leaves, and prevent fungal diseases like powdery mildew. Under good growing conditions, zinnias rarely fall prey to serious insect infestation, but if the leaves are really getting destroyed by bugs like caterpillars or spider mites, a spray of Bt or neem oil can help. Zinnias are deer-resistant, so that’s one great big pest you won’t have to worry about!
Saving Zinnia Seeds
The easiest way to propagate your zinnias is to allow them to reseed themselves. If you leave the last few flowers of the season to dry on the plant, their seeds will fall naturally into the bed, and you’ll most likely have more zinnias come spring. Bear in mind that if your neighbors also have zinnias, or you are growing a mix, the flowers will cross-pollinate each other and the next generation won’t be the pure variety (or varieties) that you planted. If you want to save pure seed from a particular variety, you’ll have to place organza or muslin bags (like the ones in our Seed Saving Kit) over some of the flower buds before they open, to prevent the bees from getting to them. Then, allow the flowers to dry completely on the plant. They’ll look a little ugly for a while, but this is the only way to be sure the seeds mature fully. Once the flower heads are dry, or very nearly so, clip them off and shake or beat the seeds out into a container. If the seeds are not crunchy-dry just yet, lay them out on a towel somewhere indoors for a few days to finish the drying process. Then store them in a sealed container in a dark and dry location.
We hope you feel inspired to add a rainbow of color to your garden this year with easy-to-grow zinnias. Looking for even more flower inspiration? Learn about growing cut flowers, or edible flowers on our garden blog!
Article Written by: Leah Smith
About the Author: Leah Smith is the Seed Product Manager at Sow True Seed, where she focuses on adding new varieties to the catalog and ensuring the seed stock is top-notch. Her firsthand experience in farming has given her a deep understanding of cultivating crops while caring for the environment.