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Dahlia Care: A Guide to Growing Striking Flowers

Updated: Nov 5, 2023

Based on what I have learned over the last few years from the American Dahlia Society and Swan Island Dahlias, I am sharing a summary of how to care for your dahlias, from planting to cutting. Please get in touch with Calvin at Quail Run Dahlias for specific questions since this is a summary of how to care for these beautiful and unique flowers.

Meet Deputy Bob, my first dahlia to come up. Since my dahlias are starting to break through the soil it is time to consider using a snail bait to control those little critters that like to eat your new starts. See the note below: Pests.

Selecting a location to plant your dahlias

  • Find a location that receives direct sunlight – at least 6 hours per day.

  • Make sure the soil has good drainage.

  • Dahlias prefer to grow with other dahlias.

Soil preparations

  • Make sure the soil is well tilled, even if prepared by hand.

  • Add compost to the site where you will be planting the tubers – DO NOT use compost high in nitrogen, such as chicken manure compost or grass-based compost sprayed with a broad leaf herbicide.

  • DO NOT use products with timed-release materials such as Miracle Grow.

  • Fresh cow manure should be placed in the ground in the fall, allowing it to cure before planting your dahlias in the spring. If using steer manure, this should be well-cured manure and placed in the ground before planting. I recommend not using other manures; they are too high in nitrogen.

Planting dahlia tubers

  • Make sure the soil temperature is at least a consistent 60 degrees before planting. The rule of thumb is to wait until Mother’s Day to plant.

  • Plant dahlia tubers approximately 6 inches deep.

  • Plant tubers 12 – 24 inches apart.

  • Make sure the “eye” is facing up.

  • After planting your tubers, DO NOT water the tubers until the plant starts to show through the soil. The tuber has enough nutrients to break through the soil.

  • Do not use heavy mulch, as this may keep the ground from warming up, which is needed for flower growth.

Staking your plants

  • If your plants will grow over 3 feet, it is good to stake them to provide the support they need.

  • To prevent placing the stake through your tuber, it is best to stake them when planting the tubers.


  • Dahlias need adequate water. They DO NOT like to sit in standing water or muddy soil. They may need watering 3-4 days per week. As the summer heat increases, you may increase the number of watering days. It should be a deep watering, so the water penetrates down to the tuber roots, which will be 8”-10” deep.

  • Deep watering may take 45-60 minutes with drip irrigation or above-ground sprinklers.


  • Begin fertilizing 30 days after planting.

  • Fertilize every 3 - 4 weeks. Dahlias need nutrients to grow and produce quality flowers.

  • Use fertilizers with low nitrogen contents, such as 5-10-10, 10-20-20, or 4-10-7. I suggest using a liquid fertilizer, especially if you are using a drip irrigation system.


  • Topping keeps your plant shorter and bushier, thus allowing more energy to go to the flowers. It also helps to produce longer stems.

  • Pinch off the top of the plant just above the 3rd set of leaves or when the plant is approximately 18” tall.

Weed Control

  • I suggest hand weeding whenever possible.

  • Do not use herbicide, as it may kill your dahlias.


  • It’s best to take a preemptive perspective on bugs. It would be best if you began spraying when the stem is about 12” tall. Ortho, Bayer (BioAdvanced), and Monterey products have options for most pests.

  • Snails –As soon as you see your dahlia poking its first stem through the soil, apply snail bait at that time. You may not see the snails since they mainly do their deed at night.

  • White Flies lay their eggs on the back of the dahlia leaves. Sevin will work on White Flies, Earwigs, and Cucumber Beetles. Neem Oil is another option, especially if you have an organic garden.

Dahlias are stunning flowers that can add vibrant colors and textures to any garden. Following the tips and tricks outlined in this guide, you can ensure that your dahlias grow healthy and strong, producing beautiful blooms throughout the growing season. From selecting the right location to staking, watering, fertilizing, and pest control, these steps will help you take care of your dahlias from planting to cutting. By taking the time and effort to care for your dahlias, you can enjoy the fruits of your labor and take pride in your beautiful garden.

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