How you space dahlias in your garden is important. If you give them too much space, you won’t be able to fit as many dahlias into your garden. If you space them too closely, they might not have enough room to grow and disease might plague your dahlias because of lack of airflow. Proper spacing allows enough airflow, allows you to give the plants proper support, and lets you use your space in the most efficient way possible.
How much space do dahlias need?
We plant our dahlias with 12 inch by 12 inch spacing in double rows in our fields. We’ve experimented with smaller and larger spacing, but our dahlias did best at 1-foot spacing. Some dahlias, such as Nicholas, need a bit more than 12 inches for their leaves/blooms to expand as much as they want, but we’ve found 12 inch x 12 inch spacing to be perfect for tuber development and for most dahlias (even dinnerplates) to thrive. Tighter spacing often helps them grow taller, too, since you’re giving them no option other than to grow up. Be careful not to crowd your rows of dahlias, though. Your plants need plenty of air circulation to avoid being overwhelmed by powdery mildew and other diseases. We use 4’ to 6’ aisles in between our rows of flowers to ensure they aren’t too crowded.
If you aren’t planting in rows, still be mindful of air circulation around your dahlias. If they are surrounded by perennials, too tight against your home or a fence, or in an area that is a “dead zone” for airflow, they won’t be very happy.
Spacing Dahlia Seedlings
We plant our seedlings out in the field in the four inch pots that we started the seeds in. For more info, check out our blog post all about how we plant dahlia seedlings here on the farm.