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Growing Dahlias: A Guide for Vibrant Blooms and Snail Resistance

At Zetas, we cultivate dahlias every year. The dahlia is a vibrant classic that adds a spectacular touch to bouquets. To encourage earlier blooming and better resistance against the Spanish forest snail, we recommend pre-cultivating dahlia bulbs. March-April is an opportune time to awaken the bulbs. If you procure your dahlia bulbs early in the season and need to store them for a few weeks before pre-cultivation, store them cool and dark, in a paper bag or cardboard box.

Upon receiving your dahlia

Remove the dahlia from the bag. Lightly spray the bulb if it feels dry. Plant it, if desired, in some soil. Then store it in a dark and cool place (frost-free around 5-8 degrees Celsius) until it's time to pre-cultivate it.

How to pre-cultivate dahlias

  1. Use a plastic bucket or pot with a hole in the bottom, preferably 20 liters.
  2. Fill it with nutrient-rich planting soil and plant the bulb 10 centimeters below the surface.
  3. Place the bucket in a bright and cool location.
  4. Move the plant outdoors when the risk of frost has passed, around mid-May, but this depends on your location. Be prepared to have fleece covers on hand to protect against cold nights for a few weeks.
  5. Water sparingly until green shoots begin to emerge from the soil.
  6. Care for the plant like a regular potted plant.

The plants become more robust if they are topped when they are about 20 centimeters tall. Trim just above a pair of leaves to encourage branching, resulting in a sturdier plant that produces more flowering branches. But don't discard the top, it can be used as a cutting!


Plant dahlias when the risk of frost is over. They can be grown both in pots and in open ground. For container cultivation, we recommend pots of at least 30 liters for low-growing varieties and at least 40 liters for tall varieties. A good planting distance between bulbs is 50 cm, slightly more if it's a very tall variety. Plant in well-fertilized soil and fertilize a few more times during the season until September. Zetas dahlia fertilizer works well! In September, dahlias should begin their maturation for winter dormancy, so fertilization should cease.


Water regularly, which is especially important if dahlias are grown in pots. They do not like to dry out. Moreover, there is a greater risk of powdery mildew attack if potted plants have dried out repeatedly. Powdery mildew thrives in dry and warm weather, giving dahlias' leaves and buds a white powdery coating. Therefore, it is important to water generously and regularly during warm and dry summers to prevent attacks.


During the season, remove faded flowers from the plants. This extends the flowering period. However, to collect your own seeds, the flower needs to remain on the plant and dry until the seeds are mature. Tall varieties need support during the summer.

Dahlias are a robust and easy-to-care-for plant that is avoided by deer but loved by slugs and snails. If you have a lot of snails and slugs, it is best to pre-cultivate dahlias before transplanting. Otherwise, small tender shoots can easily become food for snails. Container cultivation is also preferable.

Overwintering dahlia bulbs

The bulbs can withstand a frosty night, even if the leaves have withered. But if there are several cold nights, the bulbs need to be lifted. Dig up the bulbs with a pitchfork. There is less risk of damaging the bulbs with a pitchfork compared to a shovel. Shake off most of the soil. Trim everything except 10 cm of the stems. Remove old bulbs from last year, as they may have rot that spreads to the rest of the bulbs. Also, remove any thin feeder roots, as they contribute to drying out or rotting the bulb. Place them in a box with shavings or peat. The shavings/peat prevent drying out but also remove excess moisture. If you have many different dahlia bulbs, it's good to label them with names. Store the bulbs frost-free and in the dark.


Good luck!


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