
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 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.
-
Dahlias with sprouting greater than 3-4" should be planted in a pot first and slowly hardened off. Position the tuber so the sprout is facing upward.
-
Do not water your dahlia until a set of true leaves has formed.
-
After hardening off your dahlia, 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.