How to Plant Dahlia Bulbs

Dahlias that sprout from dahlia bulbs are an excellent perennial choice for your garden. Colorful late bloomers, dahlias will liven up your garden well into the autumn months. Planting dahlia bulbs, or tubers, is common, since the bulbs are often stored inside for the winters in cold climates.

Planting Materials 

  • Dahlia tubers
  • gloves, hat, sunglasses
  • organic compost (humus, manure, peat moss, sand, bone meal)
  • stakes (metal, bamboo)

Step 1- Where to Plant

Dahlias prefer a well-drained, sunny growing area. If your soil is heavy, prepare for planting by adding to the soil an equal mixture of some or all of the following: peat moss, humus, manure and sand. If using fertilizer, choose one with a low nitrogen percentage. Nitrogen is the first letter in the three letter combinations, so a 5-20-20 is a good fertilizer for dahlias. Mix the fertilizer in at a ratio of 4 pounds per 100 square feet. 

Choose a plot that gets full sun at least half of the day. Plan out where your plants will go. If you have different sizes of dahlias, plant larger ones in the back. If you have a variety of colors, layout your color scheme. 

Step 2- When to Plant

Dahlias should be planted in warm soil (above 60 degrees). Mid-April or May is generally considered an ideal time to plant your dahlias. If you want to start early, plant the tuber in a container a couple weeks before the predicted last frost. Move under a grow lamp or beside a sunny window after it sprouts. Transplant after the first frost, after the soil begins to warm. 

Step 3- How to Plant

Dig holes around 6 inches deep, and about 18 to 36 inches apart, depending on the size. If planting rows, they should be about 3-5 feet apart. The larger the plant, the more space needed between plants. If your plants are too close together, they will grow taller as they reach for the sun, and their blooms will be fewer. Also, poor air circulation will breed mildew.

Lay tubers in the hole horizontally, with the "eye" facing up. Add a handful of bone meal in the hole, but not fertilizer which may damage the root system as it grows. Cover with about 3 inches of soil. When the sprout pushes out of the ground, gradually add more soil to support the stem.

Dahlias usually need help growing straight, so pound in a 4-foot stake next to the hole at planting time to avoid damaging the tuber later.  


  • When handling the dahlia tuber, take care not to damage the "eye," the opening for the sprout or growing point of the dahlia.
  • Begin watering after the tuber sprouts. Watering before can cause mildew.
  • Water the soil directly. Watering the plant causes mildew and disease on the greenery and wastes water.
  • Start tying your dahlia to the stake after it reaches 1 foot. Tie every 18 inches. 

In the autumn, after the blooms die, dig up the tubers and store in a cool, dark place over the winter. In spring, your dahlia bulbs will be ready for you plant again!