Growth Habit: Dahlias grow quickly, producing bush plants and flowering in the first season.
Watering: Water regularly, and try to keep your foliage dry. Avoid overwatering, as soggy soil can lead to rotting tubers. We recommend less frequent, but deep watering.
Fertilizing: Dahlias respond dramatically to feeding. After all, they are making large potato-like roots, and the more food they get, the more root mass they'll make. This not only increases your growth of leaves and flowers, it also increases your tuber clump for an even bigger show the following summer.
Mulching: In very hot, dry areas, you may want to mulch to help retain moisture, but in most areas, we recommend skipping mulch so that the soil can stay warmer and foliage can stay dry.
Pests & Diseases: Dahlias are surprisingly free of most pests. Most years I've grown them, I've needed no spray or other insecticide. But they can be a magnet for slugs. Be ready with slug bait, and watch for them. Slugs can do lots of damage in no time.
If you find your Dahlia leaves chewed, it's most likely from caterpillars. We recommend looking leaves over and picking them off if you find them. If you find powdery mildew, we recommend Serenade, and avoiding too much watering on leaves - it may also help to spread out or thin your planting to prevent the spread of powdery mildew. Stem rot may occur in poorly draining or overly wet soil.
One year, Japanese beetles from nearby roses discovered my dahlias, and that had to be handled. They can obliterate not only the leaves, but the dahlia flowers, too. So be watchful, and keep the plants pest-free by occasionally flicking any Japanese beetles into a container of soapy water.