Whether you direct sow or transplant seedlings, getting the spacing of your zinnia flowers is important and it depends on what you intend to use the flowers for. Cut flower production spacing will be different than the spacing for zinnias grown to enjoy in the landscape or flower bed.
In either scenario, providing enough space between plants is also essential to keeping them healthy. Let’s take a look at how you should space your zinnias to do just that.
Zinnias should be spaced nine inches apart when grown for cut flowers. For landscaping and flower beds, plant zinnias seeds and seedlings 12-18 inches apart depending on the variety.
Now for the specifics of spacing out your zinnias according to the growth habit and use.
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How far apart should zinnias be?
Zinnia seeds should be planted about nine inches apart if you are growing them for cut flowers. This way the plants are encouraged to grow tall, straight stems, and it makes harvesting the flowers easier when they’re grown in a compact area.
On the other hand, if you grow zinnia flowers to enjoy them right in the garden, or perhaps to attract pollinators, then you’re better off giving the plants more space. 12-18 inches between plants is appropriate since they won’t be pruned as frequently as those grown for cutting.
If you grow zinnias in your vegetable garden as a companion plant, you’ll want to give them the right amount of space for their purpose. If they’re companion plants but you know you’ll be cutting blooms, go ahead and use the tighter spacing.
If the zinnias will be allowed to mature to their full size and be enjoyed primarily in the vegetable garden, then give them a little more room.
Here is a quick guide to zinnia spacing, along with some example varieties for each category.
|Spacing for cut flowers
|Spacing for landscaping
|Benary’s Giant series
|Art Deco Mix
What happens if you plant zinnias too close together?
Planting zinnias too close together can increase the risk of diseases such as powdery mildew and leaf spot as well as create competition for resources such as sunlight and water among the plants.
This disease appears as a white or gray fuzz on the plant leaves, leading to discoloration and wilting. It rarely kills the host plant, but it renders the flowers unuseable as cut flowers, and easily infects neighboring plants. Fungus spores on the leaves promote the spread of powdery mildew, so if zinnias are planted too close together, the spores can easily transfer from one plant to the next.
With enough space between plants, the air circulation improves, which leaves room for the spores to be blown away instead of directly passed on to the plant next to it.
If you live in a humid climate, the risk of disease is even greater. I lived in South Carolina for a while and my zinnias were never as robust as when I lived on the west coast, due to the humidity. I make sure to increase the space between the plants.
Competition for resources
If zinnias are planted too close together they’ll also be competing for resources such as water and sunlight. This doesn’t have to be a bad thing as long as you manage the garden well. For example, some crowding can be beneficial if you’re growing zinnias for cut flowers, as it encourages upward growth and tall stems that are good for cutting.
Tight spacing encourages tall stems as the plants grow upward, but be certain that you direct sow the zinnia seeds in a location with full sun so each plant has the best chance to grow tall, without some plants drowning out others.
Also, you will likely need to water more heavily since the plants are concentrated in a smaller area. Use drip irrigation to deliver water directly to the root zone, or overhead water in the morning so the leaves and flowers can dry off over the course of the day.
On the other hand, if you plant the whole packet of zinnia seeds in a very small area, not only will you get smaller flowers as the plants compete with each other, you will probably get weak-stemmed plants that are more susceptible to falling over in a strong wind or rainstorm.
How many zinnias can I plant together?
You can plant two zinnias per square foot when planted nine inches apart for cut flower production. If you’re growing taller varieties for your landscaping or flower bed, you can fit one plant per square foot. Dwarf varieties can also be planted two per square foot.
Mass plantings of dwarf or bedding zinnias will be best planted close together so the foliage can fill in the space between plants. Plus, because the plants won’t reach a large size even when they’re mature, they don’t need as much space between plants.
For tall varieties grown in the landscape, 12-18 inches of space between plants is best, as that will allow the plants to fully branch out for the largest blooms. If that feels like a waste of space at planting time, keep in mind that the plants will grow quickly as the weather warms. In a matter of months, the garden will be filled with vibrant colors.