How to Grow Dahlias from Tubers

Plant dahlia tubers in spring after the last frost, placing them horizontally in well-draining soil with the eye pointing up, then water regularly and stake tall varieties for stunning summer blooms.

1. Wake Up Your Tubers. Inspect your dahlia tubers in early spring, looking for firm, plump tubers with visible eyes or growing points. Remove any soft, rotted, or shriveled portions with clean pruning shears. If you stored tubers over winter, bring them out of storage 2-3 weeks before your last expected frost date and place them in a warm, bright location to encourage eye development.
2. Find Full Sun First. Select a sunny spot that receives at least 6-8 hours of direct sunlight daily. Dahlias need well-draining soil to prevent tuber rot, so avoid low-lying areas where water collects. The location should also be protected from strong winds, especially if you plan to grow tall varieties that will need staking.
3. Build the Perfect Bed. Work the soil to a depth of 12-15 inches, mixing in 2-4 inches of compost or well-aged manure. Dahlias prefer slightly acidic to neutral soil with a pH between 6.0-7.0. If your soil is heavy clay, add coarse sand or perlite to improve drainage. Create planting holes that are 4-6 inches deep and twice as wide as the tuber.
4. Set Tubers Horizontally. Wait until soil temperature reaches 60°F and all danger of frost has passed. Place tubers horizontally in the planting holes with the eye or growing point facing up. Cover with 2-3 inches of soil initially, leaving room to add more soil as shoots emerge. Space tubers 12-18 inches apart for smaller varieties and 18-24 inches apart for larger types.
5. Stake Now, Thank Later. For dahlias that will grow over 3 feet tall, install stakes at planting time to avoid damaging the tuber later. Drive 5-6 foot stakes 6 inches from each tuber, pushing them 12 inches deep into the soil. Use bamboo, metal, or wooden stakes that can support the mature plant's weight.
6. Start Slow, Then Steady. Water lightly after planting, just enough to settle the soil around the tuber. Avoid overwatering until shoots appear, as this can cause tuber rot. Once green shoots emerge and reach 6 inches tall, begin regular watering, providing about 1 inch of water per week through deep, infrequent watering sessions.
7. Mulch, Fill, Fertilize. Apply a 2-3 inch layer of organic mulch around plants once shoots are established, keeping mulch 2 inches away from the stems. As plants grow, gradually fill in the planting holes with additional soil until level with the surrounding ground. Begin fertilizing monthly with a balanced fertilizer once plants reach 12 inches tall.
8. Pinch for More Blooms. When plants reach 16-18 inches tall, pinch out the growing tip to encourage bushier growth and more flowers. As stems grow, tie them loosely to stakes using soft plant ties or cloth strips. Check ties regularly and adjust as needed to prevent cutting into the stems.