Growing & Storing Dahlias
I consider dahlias the queen of flowers. They are un matched in their beauty. Dahlias are not hard to grow. They just take their sweet time. That’s why starting with an already sprouted tuber is such an advantage. Growing your own dahlia also means you can harvest your tubers in the fall for next spring. Dahlias are exceptionally good at reproducing themselves. Your tuber will turn into multiple tubers underground. Keep reading for my instructions on storing tubers over winter.
Growing Dahlias
Choose the right time: Plant after the last frost when soil is warm (at least 60°F).
Pick a sunny spot: Dahlias need 6–8 hours of direct sun daily.
Prep the soil: Well-draining, loose soil. Mix in compost if needed.
Plant the tuber: Lay it horizontally 4–6 inches deep, with the sprout facing up. If you need to cover the sprout completely, that is fine.
Space properly: Give about 18–24 inches between plants.
Don't over water: Water after planting and then wait for green growth above ground before watering again.
Support them early: Install stakes or cages when planting to avoid damaging roots later. Dahlias can get quite tall and need some support. You can place a stake at planting and then tie the stalk to it as it grows. A tomato cage works well too!
Feed: Once established, fertilizing monthly with a low-nitrogen fertilizer is helpful. I like Neptune’s Harvest.
Pinch for lots of blooms: When plants are about 12 inches tall, pinch the top growth to encourage branching.
Dahlias as cut flowers: Harvest dahlias early in the morning or late in the evening, when it's cool.
Cut them when the blooms are fully open — dahlias don’t continue to open after cutting. The petals should be firm, not soft or wilting. Dahlias don’t have a long vase life, but they are so beautiful that we forgive them for it!
Deadhead spent blooms: Remove fading blooms to keep plants blooming longer.
Storing Tubers
There are many ways to store tubers overwinter so I encourage you to research what will work best for you. I use a plastic wrap method that gives me a success rate over 90%. All methods aim at controllinmg two factors: moisture and temperature. Here’s how I store tubers:
Dig dahlia tubers: Carefully dig clump after the first frost blackens the foliage but before the ground freezes.
Wait about a week after the frost to let the tubers cure in the ground, then dig them up on a dry day.
Clean tubers: Gently remove soil after digging them up. I blast them with a hose after digging. Let them dry for a day or two.
Divide Tubers: Use a hand pruner or sharp knife to separate the tubers. A viable tuber must be plump and dry. Size of tuber does not matter AT ALL. A viable tuber has three parts—the tuber, an intact neck, and the crown (a piece of the main stem.) The crown must have at least one eye. These “eyes” are where the tuber will form sprouts next season. It can be hard to spot eyes so do your best and focus on cutting tubers to have tuber, intact neck, and crown. Reference pictures below.
Dust with cinnamon: Sprinkle on cut areas to prevent rot and mold (it's a natural antifungal).
Wrap individually: Wrap each tuber in plastic wrap to keep moisture in and prevent shriveling.
Store cool and dark: Keep at 40–50°F in a dry, dark place (like a basement or garage fridge). I use a wine fridge.
