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Dahlias Care Guide

A Guide to growing Dahlias

Dahlias can be tricky. 

We have tried to "crack the code" for you and created

this guide to help you grow your dahlias with ease.  

 

Site and soil preparation

  • Chose a bright sunny spot that will get an average of 7 to 8 hours of sunlight.  

  • Dahlias require good drainage.  Loosely amend the soil 18” wide by 18” deep.  

  • If you are amending with store bought soil, avoid those that contain chemical fertilizers and/or fresh manure that can be caustic to your tubers.  

 

 

Protection

  • Gophers like dahlias: If you are planting directly in the ground, protect your tuber with a gopher cage or cage formed with 1/2” hardware cloth.

  • Dahlias do well in both pots and raised beds, but will require increased watering during the growing season.

 

 

When will my dahlias sprout?

  • Dahlias are all different. Some dahlias can take up to 6+ weeks to sprout! 

  • Plan to plant your dahlias when soil temperatures are above 60 F degrees.

  • Avoid planting if there is either prolonged rain or high temperatures forecasted.

 

 

What do I do if my dahlia has sprouted? (Hardening off)

  • If your tuber has any sprouting or leaf development, it is likely not ready to be planted directly in its final growing location or exposed to full sun.  

  • If your tuber has 1-2” of sprouting, you can plant directly as described below (“Planting and Staking”) and gently backfill the entire sprout with soil.  

  • Leggy sprouts of 4" or greater will probably not form strong sturdy plants.  When this happens, we simply trim the long sprout and try to root the spout as its own plant.  The tuber can then be planted as a tuber with a live eye.  

  • Do not water your dahlia until a set of true leaves has formed.

  • If you've started your dahlia off in a pot indoors, be sure to harden off your dahlia and carefully transplant it to its final growing location on a cool day to avoid transplant shock.  

 

 

Planting and staking

  • For the home gardener, dahlias should be planted approximately 4" deep and 24” apart to allow for ample air circulation which helps decrease the risk of disease.

  • Place the tuber side-lying with any visible “eyes” or sprouting face up.  

  • Before back-filling with soil, spike a 3+ foot stake a few inches away from the tuber.

 

Watering

  • DO NOT WATER YOUR SOIL OR DAHLIA until you have visible signs of a green leaves! This includes protecting your dahlia from rain. 

  • Once leaves have developed, water deeply 2x to 3x a week at soil level.   

  • Avoid overhead watering.

 

 

Pinching

  • When your dahlia has reached a height of about 12”, pinch the center stalk to promote side branching.

  • As your plant matures to about 3 feet in height, pinch off the bottom 2 to 3 sets of leaves to improve air circulation.

  • Use twine or string to tie your dahlia securely to the stake as it grows.

 

 

Feeding

  • Dahlias are heavy feeders.  Feed monthly with a “Bud & Bloom” fertilizer that can be gently worked and watered into the soil.

  • Supplement with foliar feeding when temperatures are around 70F, ideally early morning or dusk to avoid leaf burn.

 

 

Prevention & treatments for common diseases/pests: 

  • Many common diseases can be avoided by proper feeding and watering. 

  • Companion planting:  Nearby plantings of mint, basil, or fennel/dill can attract beneficial insects to control “enemy” insects

  • Leaf miner:  Remove infected leaves.  Spray with neem oil.

  • Powdery mildew:  Remove infected leaves. Spray with baking soda solution, neem oil, or Copper Fungicide.

  • Snails/slugs:  Sprinkle the perimeter of your planting area with diatomaceous earth or Sluggo Plus.

 

 

ENJOY!   Dahlias make excellent cut flowers!!  

  • Fill a bucket with tepid water about 4”+ deep. 

  • Harvest dahlias in the early morning when they are 75% developed/open.

  • Using clean and sharp snips, cut stems at an angle and place directly into water.

  • Allow dahlias to rest and hydrate in a cool dark place for several hours prior to use.

  • To maximize vase life, use floral food or a floral preservative.

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