These flowers grow best in full sunlight with well-drained soil.
Shoots emerge from tubers that become new dahlias.
Soil
Dahlias prefer rich, loamy soil with plenty of organic matter that drains well.
The Spruce / Letícia Almeida
If you’re unsure of your soil being rich enough, mix in some compost.
Dahlias thrive in a neutralsoil pHof around 6.5.
These flowers do not need water before their root system develops.
The Spruce / Letícia Almeida
Once sprouted, water your dahlias once or twice a week.
verify to water deeply, as large tubers may be planted six inches deep.
Wait until thefinal spring frosthas passed and the ground temperatures have reached 60 degrees.
The Spruce / Letícia Almeida
you could start tubers in containers indoorsperhaps in a garage or greenhouseto get them off to a quick start.
It’s safe to plant dahlias outdoors when all danger of frost has passed.
Fertilizer
Dahlias are heavy feedersthe more food they receive, the larger the plant will grow.
The Spruce / Letícia Almeida
Fertilizing your dahlias makes the flowers grow larger and in higher numbers.
Use a fertilizer with ahigh percentage of phosphorus(perhaps a 10-30-20 ratio) to promote blooming.
For the amount, follow the product label instructions.
Beate Zoellner/ Getty Images
Do not use fertilizer with a high percentage of nitrogen.
Too much nitrogen creates lush foliage but few blooms.
This discourages more growth late in the season as you prepare the tubers for dormancy.
These compact border dahlias will remain covered in flowers all season.Photo Courtesy of Longfield Gardens
Types of Dahlias
Dahlias come in many different patterns, textures, and colors.
This will help the plant grow multiple new stems in place of the pinched central stem.
Deadheading flowers after they die back also encourages your dahlias to grow fuller and with more blooms.
Propagating from cuttings requires waiting until your tubers sprout in the spring.
Come summer, your plants will be fully mature and may flower earlier.
Plus,dividing your tubersbefore planting yields more plants and, ultimately, more flowers.
Here’s how:
Potting and Repotting
If you’regrowing dahlias in pots, larger containers are best.
A good rule of thumb is to use a container that is at least 12 inches deep and wide.
it’s possible for you to also grow compact dahlia varieties, which require less space.
These flowers are too tender to leave in the ground all winter long in most zones.
To do so, pick the healthiest plants from your garden, then wait for the first hard frost.
Cut the plant back to 4 inches above the ground.
Leave the tubers in the ground for one week before digging them up.
Dig up each root ball starting at least 1 foot away from the stem.
Carefully remove the tubers (taking care not to damage them) and clean off excess dirt.
A basement or root cellar works best; just don’t let them freeze.
Common Pests & Plant Diseases
Common pests likeslugs,earwigs, caterpillars, andthripsadore dahlias.
Slugs are especially problematic when the foliage is young and tender.
Once the plants mature, slugs are usually not a problem.
Some gardeners have trouble with deer, while others claim the deer avoid their dahlias.
This may simply depend on the variety of other plants in your garden.
Keep your flowers protected, just in case.
Dahlias are also prone topowdery mildewand other fungal diseases.
Keep the foliage as dry as possible and space out your plants to provide good air circulation.
If you notice an infection, treat it with neem oil or another natural solution.
Dahlias reach maturity and bloom about eight to ten weeks after planting in late spring.
How Long Do Dahlias Bloom?
What Do Dahlia Flowers Look and Smell Like?
Dahlia flowers vary widely in appearance.
Some dahlias have double-flowering blooms, while others have flowers that are slightly rolled at the tip.
Dahlias can also have slightly overlapping petals.
In general, most dahlia flowers are circular in shape.
Fertilize your dahlias every two weeks to allow flowers to proliferate.
An organic fertilizer that is high in phosphorous will assure a good flowering rate and strong stems.
Deadheading Dahlia Flowers
Always deadhead your dahlia plants as soon as the flowers are spent.
Removing dead flowers promptly will encourage more blooms.
There are a few common problems you may encounter when growing this species.
Wilting Flowers
Dahlias may topple over and wilt during the heat of a midsummer day.
This is not necessarily a problem, as it’s the plant’s way of adapting to stress.
If the bed is moist, your dahlias should perk back up once the sun goes down.
Dahlias will only come back in hardiness zones 8 through 10.
Dahlias do multiply on their own.
Dahlia.ASPCA Animal Poison Control.
Summer-Flowering Bulbs: Plant Now; Enjoy Later.University of Missouri Division of Plant Sciences.
Growing and Caring for Dahlias.University of Idaho Extension.
Powdery Mildew.Clemson Cooperative Extension.
How to Grow Dazzling Dahlias.Rutgers Cooperative Extension.
