How to plant dahlias

Posted by Sarah Kistner on

Learn the right time to plant your dahlias

Plant your dahlias in late spring, once the soil has warmed and the danger of frost has passed. It can be tempting to try to get a jump start on the season, but if you plant to early you take the risk of rotting your tubers in cool wet soil!

  • The soil should be warmed to at least 60F (15C)
  • The plants can't tolerate a frost, so wait until after your last spring frost to plant

Plant your dahlias in an open, sunny location in well drained soil. Heavy soil that retains a lot moisture can cause your tubers to rot. Too little sun will grow lanky plants that may not make many (or any!) flowers. 

  • Dahlias need a minimum of 6-8 hours of full sun
  • Tubers perform best in well-drained soil

Healthy soil grows healthy plants! We typically amend our field with compost and a balanced organic fertilizer that we lightly mix into the soil before planting.  But to truly know what your soil needs, we recommend a soil test prior to planting. Remember that you can have too much of a good thing! 

Ready to plant?!

Once you have your garden prepared you're ready to plant!

Start by digging a hole 4-6" deep and long enough to lay your tuber in the hole horizontally. Place it in the hole with the eye facing up. We recommend staking your dahlias to keep them from toppling in the wind, so this is a great time to pound a wooden or bamboo stake in the ground right next to your tuber and then cover the tuber up with soil. Plant your tubers approximately 18" apart. If you are planting a large quantity, you can dig or hoe a long trench to lay them in and cover the trench using a hard rake.

Planting dahlias in a trench

 

Because tubers can rot in overly moist soil, many growers recommend not watering until you see green shoots just starting to show above the ground. However, if you live in a hot and dry climate, I suggest giving them a light watering to moisten the soil after planting. If your soil is moist or you’re in a rainy climate you do not need to water until the plant makes a green sprout and begins growing roots. Overwatering newly planted tubers can cause them to rot!

Summary

  • Plant after the danger of frost has passed
  • Soil should be minimum of 60F
  • Plant in a location with a minimum of 6-8 hours of full sun
  • Plant about 18" apart
  • Plant tubers horizontally about 4-6" deep
  • Stake your plants to prevent toppling
  • Water newly planted tubers only in dry climates

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