Dahlia Care & Planting Guide
Some Guidance On Growing Dahlias ~
CHOOSING A GROWING SITE - Dahlias prefer a site with good drainage and 6 or more hours of sunlight daily. In southern growing areas dahlias will struggle with the heat so choose areas with afternoon shade.
Dahlias prefer rich and well-drained soil. Prepare the soil with compost or decomposed manure, and then work in a good organic fertilizer according to the instructions. Loosen the soil several inches deeper than the required planting level to help with drainage.
PLANTING - Plant tubers so the highest surface of the tuber is 2-4 inches below soil. We dig a 6” deep trench, lay the tubers on their sides, and backfill, being careful not to break the sprout if there is one. Timing will vary with location, but plant so emerging foliage will not get frosted. If it’s not time to plant your dahlias when you receive them, keep them in a cool, dry place. (Basements or roots cellars are good options. A garage will do if they won’t freeze.) You don’t want them to shrivel and dry out too much. Keep them covered with the vermiculite or wood shavings and LIGHTLY mist them with water if they start showing a wrinkle. If tubers sprout in storage, that’s fine. Just snip the sprout back to about an inch when planting.
WATER - It’s tempting to water when you plant, but do not water your tubers until the foliage has sprouted above the soil. Thereafter, water regularly but try to keep your foliage dry. We recommend less frequent, but deep watering. Mulch heavily to help reduce moisture loss, keep the roots cool, and reduce soil splashing onto the plants.
BEST BLOSSOMS - We recommend supporting your dahlia tubers. At a farm scale, stakes with floral netting stretched between the posts works great. In the home garden, tie plants to stakes or use tomato cages. Like tomatoes, dahlias will suffer if they are allowed to sprawl onto the ground.
Remove flowers that are past their prime to keep plants looking good. More importantly, pruning encourages plants to produce new buds and helps control pests and disease. Use flower snips or pruning shears to cut the spent flowers back to a main stem. Cut deeply to help stimulate new growth, encourage longer stems, and create a more compact, healthier plant.
ONGOING MAINTENANCE - It will help to dramatically thin your plants to prevent the spread of diseases. Once plants are well established, remove grungy foliage from the underside of the plants. Airflow will help keep disease from building up. If you have problems with powdery mildew, we recommend a scheduled application of an organic fungicide like Serenade.
END OF THE SEASON - Fall frost will kill the plants to the ground. If you live in a warm climate (zone 7 and warmer) you can leave the plants in the ground over the winter. In more northern areas you should dig up the tubers and store them for the winter. When frost kills the foliage to the ground, cut the plant to a stub. Wait a few weeks, dig the entire clump, and clean off the dirt. We like to separate the tubers in the fall, but lots of gardeners store the entire clump and separate the tubers in the spring when sprouts are obvious. Store dahlias for the winter in a dark, dry, and cool space like a basement. We store tubers in cardboard boxes covered with vermiculite.