The real secret to growing dahlias comes down to three things: full sun, proper pinching, and low-nitrogen feeding. Most people get the sun part right but skip pinching and use the wrong food. Fix those two mistakes and your dahlias will go from average to stunning.
Pinching changed my dahlia garden more than any other trick I have tried. Three years ago I pinched half of my plants when they hit about 1 foot (30 centimeters) tall. I left the other half alone. The pinched plants branched out wide and grew two to three times more flower stems than the others. The unpinched plants shot up tall on single weak stems that fell over in every storm.
PSU Extension says to pinch the top shoot when your plant has 3 to 4 pairs of leaves. Just snap out the growing tip between your thumb and finger. This forces the plant to send energy into side branches rather than racing straight up on one stem. You get a shorter bushier plant loaded with more blooming points.
Your choice of fertilizer matters just as much as pinching. Use a low-nitrogen formula like 5-10-10 once a month. The low first number keeps your plant from wasting energy on leafy green growth. The higher middle and last numbers push energy toward roots and flowers instead. Stop feeding once buds start to open.
These dahlia growing tips work best when you use them as a team. Give your plants 6 to 8 hours of direct sun each day. Plant them in soil you have mixed with 2 to 3 inches (5 to 7.5 centimeters) of compost. Water deep once or twice a week instead of a light sprinkle every day. Deep soaks push roots down into the soil where they find moisture during dry spells and anchor the plant against wind.
UGA CAES research found that late plantings often produce the best flowers of the whole season. Dahlias thrive in the cooler air of September and October. Summer heat can slow flower growth and fade colors. Try planting a second batch of tubers in early June. Those plants will peak in fall when the air cools and your blooms will be bigger and richer than anything you grew in July.
If you want to know how to grow better dahlias, commit to these five steps this season. Full sun. Compost in the soil. Pinch at 1 foot (30 centimeters) tall. Feed monthly with low-nitrogen food. Water deep not often. This formula gave me the best dahlias I have ever grown and it will do the same for you.
Read the full article: Dahlia Tubers: A Complete Growing Guide
