How to Plant Dahlias – Dahlias Growing Guides

Dahlias are spectacular flowers to grow in your garden, offering showy and beautiful blooms from midsummer until frost. There are hundreds of hundreds of varieties with flower sizes ranging from one inch in diameter to a mammoth fourteen inches. Most gardeners consider Dahlias very easy to grow.

Growing Dahlias from Tubers

Dahlias can be grown from tubers or seeds. If you choose to purchase tubers, they can be planted like daffodils or tulips. Ensure to wait until the weather is warmer and all threat of frost has passed before planting dahlia tubers. Planting too early will result in poor blossoms.

Where to plant: Dahlias require a spot in the yard that gets at least six hours of sun per day. They will do well in any soil that is well-drained but thrive particularly well in slightly acidic, sandy loam.

How to plant: Dahlias require good airflow, so how far apart you space them will depend on the variety and type that you are planting. As a general rule of thumb, small dahlia plants should be spaced a few feet apart, while large varieties require three to four feet between plants as well as rows.

Dig a hole 6 inches deep and lay the tuber in the hole flat on its side. Cover with soil, followed by a thin layer of mulch. You do not need to water until the first sprout appears.

If you are planting large dahlia varieties that will require staking, place the stakes when you plant the tuber. Dahlia roots grow close to the surface and are fragile, so later staking could injure the plant.

End of Season: In zone 7 and colder, dahlia tubers need to be dug up and brought inside at the end of the season. Warmer areas that include zone 8 and higher do not require digging up.

Starting Dahlia Seeds Indoors

In warmer hardiness zones, dahlia seeds can be sown directly into the garden beds where they will be grown. In more temperate zones, dahlia seeds should be started indoors.

When to plant seedlings indoors: You should start your seedlings 4-6 weeks before the last spring frost.

How to plant: ow seeds in seedling trays or individual 4-inch pots about ¼ inch deep into the growing medium. Keep soil moist but not wet.

Germination temperature: 70 – 85 degrees Fahrenheit.

Days to emergence: 7 – 14 days

Planting prep: Once plants have been established, in about five weeks, they can be hardened for transplanting outdoors by bringing the plants outside on warmer days to acclimate them. Once all danger of frost has passed, they may be directly transplanted into your garden.

Tips for Dahlia Care

Dahlias should receive regular and thorough watering, and the soil around them should never be allowed to dry out completely. Pinch back the new growth on your dahlias when they reach about a foot high to promote lush growth and more flowers. To promote continual flowering, deadhead the plant by removing the flowers as soon as they begin to wilt.

Fertilizing: Early in the season, dahlias benefit from high nitrogen fertilizer. Once the flower buds form, switch to a high-potassium fertilizer.

Resources

• Utah State University Extension – “Growing Dahlias.”
• University of Georgia Extension – “Dahlias.”
• Mississippi State Universite Extension – “Dahlia Care.”
• Colorado State University Extension – “Planting Dahlia Tubers.”
• Alamac – “How to Plant, Grow, and Care For Dahlias.”
• Cornell University – “Dahlia: Bedding Varieties.”