“Kicking off” dahlia tubers involves waking these dormant storage roots indoors before transplanting them into the garden. This process provides a head start on the growing season, allowing dahlias to develop strong root systems and foliage in a controlled environment. Initiating growth indoors leads to earlier blooms and more robust plants once outdoor conditions are suitable, bypassing the unpredictability of early spring weather.
When to Kick Off Dahlia Tubers
The timing for starting dahlia tubers indoors depends on your region’s last expected frost date. “Kick off” dahlias approximately four to eight weeks before the danger of frost has passed, allowing tubers sufficient time to sprout and develop. For many areas, this falls in early to mid-spring, such as early April. Plan backward from your local last frost date; for example, if your last frost is mid-May, start in late March or early April. Local climate variations influence this schedule, so check reliable local resources for accurate frost dates.
How to Kick Off Dahlia Tubers
Begin by inspecting dormant dahlia tubers for firmness and signs of rot or mold. Healthy tubers should be plump and firm, even if slightly wrinkled. Trim away any shriveled, squishy, or moldy sections with clean tools.
Select pots six to eight inches across and at least six inches deep, with adequate drainage holes. Use one tuber per pot to avoid overcrowding. Fill containers one-third to halfway with a light, well-draining potting mix, such as one containing peat, perlite, and vermiculite.
Position the dahlia tuber horizontally or vertically, ensuring the “eye” or sprout-producing end faces upwards if visible. The eye is a small, raised bump near the crown where new growth emerges. Cover the tuber with one to two inches of potting mix, leaving the top of the stem end just below the soil line. Gently tap the pot to settle the soil and eliminate large air pockets without compacting it excessively.
After potting, water lightly to moisten the soil around the tuber. Overwatering can cause rot, as the tuber doesn’t need much moisture until active growth begins. Place potted tubers in a warm location, ideally maintaining a soil temperature of at least 60-70°F (16-21°C). Direct light is not necessary until sprouts appear.
Caring for Kicked Off Dahlias
Once dahlia sprouts emerge, typically within two to four weeks, relocate pots to a bright location. Young dahlia plants require ample light, ideally six to eight hours daily, from a sunny window or supplemental grow lights. If using artificial lighting, position lights about six inches above plant tops for 14 to 16 hours per day.
Maintain consistent moisture in the potting mix, keeping it evenly moist but not waterlogged. Water when the top inch or two of soil feels dry, avoiding excessive watering that can lead to rot. Temperatures between 70 and 80°F (21 to 26°C) are conducive to healthy growth.
Periodically inspect plants for pests or diseases, addressing issues promptly. As the outdoor planting date approaches, begin “hardening off” your dahlia plants. This gradual acclimation to outdoor conditions prepares them for transplanting.
Start by placing potted dahlias outdoors in a sheltered, shady spot for a few hours daily, gradually increasing exposure to sunlight and wind over one to two weeks. Bring them indoors at night, especially if temperatures are expected to drop below 50°F (10°C). This hardening off strengthens plants, reducing transplant shock when moved to their permanent outdoor location after all frost danger has passed.