Zinnias

How to Plant, Grow, and Care for Zinnia Flowers

Zinnias are one of the easiest flowers to grow, as they grow quickly and bloom heavily. Zinnia flowers can create a massive burst of color, adding an extra layer of festivity to any garden.

Zinnias are annuals, so they’ll grow for one season and produce seeds, but the original plant will not come back in subsequent years. They have bright, solitary, daisy-like flowerheads on a single, erect stem, which makes them great for use as a cutting flower or as food for butterflies.

Types of Zinnias

The most popular zinnia species is Zinnia elegans, which has been bred to produce a great number of unique varieties.

There are three main kinds of zinnia flowers: single, semi-double, or double. The distinction between these forms comes from the number of rows of petals and whether or not the center of the flower is visible:

When to Plant Zinnias

• It’s recommended that you grow zinnia from seed right in the garden bed, as they do not like to be transplanted. From seed, they will grow very quickly in the right conditions.
• Zinnias are sensitive to frost, so do not seed until the last frost has passed.
• Zinnias will grow in a minimum daytime temperature of about 16°C, though a range of 23–28°C is preferred.
• Sow a round of seeds every week or so for several weeks to extend the flowering period.

Choosing and Preparing a Planting Site

• Choosing a location that gets full sun is essential.
• Good air circulation will help to prevent foliar diseases
• Zinnias are adaptable to most soil conditions, but the ideal soil will be rich in organic matter and well-drained.
• If soil is amended with compost, the flowers will grow more quickly.

How to Plant Zinnias

• Space plants 4 to 24 inches apart, depending on variety. (Many common varieties are planted 6 inches apart within the row and 2 feet in between rows.) See back of seed packet for variety-specific advice.
• Sow zinnia seeds only about 1/4-inch deep.
• You’ll see zinnia seedlings in only 4 to 7 days for most varieties, though it will be anywhere from several weeks to a couple months before blooms appear (depending on planting site and climate).
• When seedlings reach three inches tall, thin them so that they’re 6 to 18 inches apart to maximize air circulation. This reduces the chance of powdery mildew developing.

How to Care for Zinnias

• Maintain moderate soil moisture and fertilize lightly to maximize growth and blooms.

• After zinnias flower, cut off the old flowers (a process called “deadheading”) to encourage more flowers to form.