Zinnias are annual plants, which means they will only grow and produce flowers and seeds for one season before dying. Zinnias have lovely daisy-like flowers that grow from a single stem, making them great for cutting.
We’ve broken down the lifecycle of zinnias so that you can maximize their exuberance in your garden.
Like other plants, the first stage of a zinnia’s lifecycle begins with germination, which is when the outer shell of the seed breaks open and roots form. It takes zinnias 7 to 10 days to germinate after they’re planted.
If you are planting zinnia seeds in an outside garden, we suggest preparing the soil by clearing the space of weeds and any other plants that could interfere with the plant’s growth. We also recommend planting the seeds on a day when there’s little to no wind.
Plant 1 – 2 seeds to ensure at least one zinnia plant germinates. Keep the soil damp but not wet; cover the soil where you’ve planted seeds with peat moss to maintain moisture levels. To help ensure germination, plant seeds when temperatures are between 69 and 76 degrees Fahrenheit.
Continue to maintain soil dampness as zinnia sprouts appear. If the soil is dry, apply just enough water twice daily to restore moisture remoisten, ideally in the morning and late afternoon. Adding fertilizer may also be a good idea since frequent watering can wash away the soil’s nutrients. The sprout also needs at least 6 – 8 hours of direct sunlight to continue growing.
If you’ve chosen to plant your zinnias in a planter or flowerpot, transfer them to your garden or a larger container once they reach a height of at least 6 inches. Doing so helps the roots fully develop. Once transferred, place the sprouting zinnia in a sunny spot where it can get at least 6 hours of sunlight.
Zinnia plants will produce one flower atop its stem. The flower can range in size from 1 – 7 inches in diameter and can be white, yellow, orange, pink, red, lilac, purple, or multi-colored. Zinnia blooms can feature a single row of petals or have multiple rows of petals that are curvy, twisty, or pointed in shape. Zinnias bloom from mid-summer until the first freeze.
Zinnias can be pollinated by butterflies and hummingbirds, which are drawn to the blossoms. This plant can also self-pollinate since it has both sets of reproductive organs (stamens and pistons).
Allow zinnia blooms to dry completely before removing them from the plant. Picking a bloom too soon could result in immature seeds that will not germinate. You’ll know that it’s completely dried out when the flower turns dark brown and is dry to the touch. Place seeds on a mesh screen to ensure the seed is dry on both sides before storing them for future planting.