How to Grow Dahlias: A Complete Guide from Ribier Gardens

Dahlias are one of the most breathtaking flowers you can grow—bold, intricate, and endlessly expressive. With the right care, they’ll reward you with a season-long display of vibrant color from midsummer until the first frost.

At Ribier Gardens, we specialize in growing and breeding exceptional dahlias, and we’ve learned that success begins long before planting day. Below you’ll find our complete guide to growing healthy, abundant dahlias from tuber to bloom.

Tools and Materials You’ll Need

Before you begin, gather these essentials:

• Dahlia tubers (healthy, firm, with visible eyes)

• Hand trowel or shovel

• Garden stakes and twine

• Soil thermometer

• Soil amendments (based on a soil test)

• Sluggo Plus or similar pest control

• Plant labels

• Peat moss, coco coir, or potting mix for pre-sprouting
  
  

  Step 1: Pre-Planting & Warming Up Your Tubers

  Dahlias are sensitive to cold and excess moisture before roots have formed. Warming them up before planting encourages strong early growth and helps prevent rot.

  About four weeks before planting, bring your tubers indoors to a warm (65–72°F) environment. This “wakes them up” from dormancy and signals it’s time to grow.

  Place tubers in a sealed plastic bin or bag with a loose growing medium such as peat moss, coco coir, or potting soil. This provides a gentle, breathable environment where roots can start forming. Within a couple of weeks, you’ll notice new growth points—called eyes—beginning to sprout.
  
  

  Step 2: When and How to Plant Dahlias

  Timing is everything. Wait until your soil temperature reaches at least 60°F before planting. Cold soil is one of the most common causes of dahlia failure.

  You can use a soil thermometer or check online soil temperature data for your ZIP code. Choose a sunny location with well-draining soil. Dahlias love full sun, though in very hot regions they’ll appreciate some light afternoon shade.

  Planting Steps:

  1. Dig a hole 4–6 inches deep.

  2. Lay the tuber horizontally with the eye or sprout facing up.

  3. Insert your stake before covering with soil to avoid damaging the tuber later.

  4. Backfill gently and label the variety.

  5. Water sparingly until you see growth above ground—especially in wet climates. Overwatering can cause rot before the roots establish.

  Tip: In dry climates, lightly moisten the soil occasionally so it doesn’t go bone dry, but never let the tuber sit in soggy conditions.

  To protect your emerging shoots, sprinkle Sluggo Plus or another organic pest deterrent over the soil surface.
  
  

  Step 3: Caring for Growing Dahlias

  Once your plants are about 12 inches tall, you can pinch the central growing tip to encourage branching. This may delay blooms by a couple of weeks, but it produces a sturdier, bushier plant with more flowers and longer stems—perfect for cutting gardens.

  Ongoing Care

  • Water deeply 1–2 times per week depending on your soil type and climate. Sandy soil requires more frequent watering than clay.

  • Tie plants to stakes every 12–18 inches of growth to support heavy blooms.

  • Deadhead spent flowers regularly to encourage new buds and extend the flowering season.

  • Fertilize lightly every 3–4 weeks with a balanced, low-nitrogen fertilizer once growth is established.

  If strong winds or storms break a stem, don’t panic—cut it back and your plant will send up new shoots in no time.
  
  

  Step 4: End of Season & Storing Dahlia Tubers

  When frost arrives, your dahlia season comes to an end. Wait one to two weeks after a hard frost, when the foliage has blackened, before digging. This allows the tubers to “harden off” for better winter storage.

  1. Cut down the plant to a few inches above the soil.

  2. Gently dig up the clump, being careful not to damage the tubers.

  3. Rinse off the soil and divide the clump if desired.

  4. Label each variety clearly.

  5. Cure for a day or two, then store in a cool (40–45°F), humid (70–80%) environment—such as a basement, garage, or root cellar.

  We recommend storing in plastic totes with wood shavings or peat moss, but there are many methods that work depending on your climate.
  
  

  Step 5: Restarting in Spring

  When spring returns, repeat the pre-sprouting process to get a head start on the growing season. With each year, your tubers will multiply—soon you’ll have extras to share or swap with other dahlia lovers.

  Bonus Tips from Ribier Gardens

  • Rotate your planting areas yearly to reduce disease pressure.

  • Mulch lightly to regulate soil moisture and temperature.

  • Label every plant—you’ll thank yourself later when your field is a sea of blooms.

  • Select healthy stock from trusted growers. Ribier Gardens tubers are hand-selected for vigor and true-to-name varieties.

  Final Thoughts

  Growing dahlias is one of gardening’s greatest joys. With a little patience and care, your garden will soon be bursting with color, texture, and life.

  At Ribier Gardens, we take pride in sharing not only the finest dahlia tubers but also the knowledge that helps you grow them beautifully.

  Ready to start your own dahlia patch?
  Shop Dahlia Tubers