Dahlia care guide
Dahlia
Also known as: Garden dahlia
Pets and children
Caution advised
Mild stomach upset and skin irritation are reported in dogs and cats that chew the leaves, stems or tubers; keep it out of reach and consult a veterinarian (or a doctor, for a child) if eaten.
How often to water Dahlia
- Spring–Summer (Mar–Sep)
- Every 3 days
- Once shoots are up, water well when the topsoil dries, as a guide; keep a new tuber on the dry side until it sprouts, and water mornings or evenings in midsummer.
- Autumn (Oct–Nov)
- Every 4 days
- Cooler weather brings a second flush of bloom; water well when the topsoil dries, as a guide, and stop once frost kills the top growth.
- Winter (Dec–Feb)
- Every month
- Dormant tubers are stored mostly dry; as a guide, the packing material is lightly moistened at most about once a month so they do not shrivel.
Light and placement for Dahlia
A sunny, airy spot outdoors, as a guide; it dislikes extreme heat, so in midsummer give light shade out of the western sun, while too little sun means fewer flowers.
Overwintering Dahlia
Overwintering guide: 3°C (37°F) or above
When frost kills the top, cut the stems and lift the tubers to store at about 5–10°C, frost-free, in slightly damp peat so they do not shrivel.
Fertilizing and repotting Dahlia
Fertilizer
A little slow-release fertilizer at planting, then about monthly slow-release or liquid feed every two weeks in growth; ease off in midsummer, as too much gives leaves instead of flowers.
When to repot
Spring–Summer (Mar–Sep)
Common problems with Dahlia
- Summer heat and humidity weaken the plant, powdery mildew spreads and flowering stops.
- Grown without a stake, the stems snap in wind and rain.
- Tubers stored too dry or frozen fail to sprout in spring.
Tips for growing Dahlia
- Thin to one or two shoots and pinch at four or five pairs of leaves for more branches and blooms.
- Cutting the plant back by about half in July or August brings a strong second flush in fall.
- When dividing, each piece needs a bit of the crown with an eye, or it will not sprout.
These are AI-generated general guidelines. They vary with the variety, the placement and the pot size. For effects on pets or children, consult a veterinarian or a doctor.
Keep your plant log going
Greenery is a free app that keeps your plant care going, with watering reminders and photo records. Available on iOS and Android.
