Growing dahlias can be incredibly rewarding—they’re showy, vibrant, and come in a wide variety of colors and sizes. Here are some tried-and-true tips for growing strong, beautiful dahlias:
🌱 Planting Dahlias
- When to Plant: Wait until after the last frost. Soil temperature should be around 60°F.
- Sunlight: Dahlias love sun—plant in a location with at least 6-8 hours of direct sunlight daily.
- Soil: Well-drained, slightly acidic soil (pH 6.5–7). Add compost or well-rotted manure to enrich the soil.
- Do not water after planting the tuber. Wait till green growth appears.
🏡 Spacing & Depth
- Tuber Placement: Plant tubers 4–6 inches deep horizontally and with the eye facing up.
- Spacing: Allow 18–24 inches between plants to promote airflow and prevent mildew.
💧 Watering
- Start dry: Don’t water right after planting tubers—wait until you see green growth.
- Once growing: Water deeply 2–3 times a week, especially in hot weather. Avoid overhead watering to reduce risk of fungus.
- Apply mulch around dahlias to keep the ground warm and to hold moisture.
🪴 Staking
- Support early: Place stakes or cages at planting time so you don’t damage tubers later.
- Tie stems loosely as they grow—dahlias can become top-heavy with blooms.
✂️ Pinching & Deadheading
- Pinch tips: When plants reach about 12″, pinch out the top growing tip to encourage bushier growth and more blooms.
- Deadhead regularly: Remove spent blooms to keep plants blooming all season. I know it’s hard to cut the flowers off, but at least you can bring them in the house in a vase. It promotes faster bloom growth.
- Disbudding buds: Watch this video on disbudding your dahlia buds:
🐛 Pests & Problems
- Watch for: Aphids, earwigs, slugs, and spider mites. I typically use Sluggo in all my gardens to ward off the slugs.
- Use insecticidal soap or neem oil as needed. I recently had to spray neem oil on my front yard garden due to some bugs. Keep the garden clean to prevent mildew.
🌸 Feeding
- Use a low-nitrogen fertilizer (like 5-10-10) once plants are 6–8 inches tall, then every 3–4 weeks. I use a fish fertilizer and my homemade compost.
- Too much nitrogen = lush leaves, few blooms.
❄️ End-of-Season Care
- Cut back after the first frost blackens the leaves.
- Dig up tubers in cold climates (zones 3–7). I am in zone 4b, so it’s imperative that I dig them up and store for the winter. Let them dry. After separating my tubers, I store my tubers in plastic bins and layer with vermiculite, then store in a cool, dark place (under my stairs in my basement). Watch my 2024 video on digging up dahlia tubers.
If you’re in it for show blooms, consider disbudding (removing side buds) to channel energy into one large flower. And don’t forget to label your varieties—rain has a way of washing off the labels by the time they bloom, so I suggest rechecking the labels often because you’ll want to remember which ones to grow again next season!
