Pulling the dahlias forward can bring flowering forward by four to six weeks. The tubers are often soaked in the process. However, these methods also come with some risks. We clarify.

Dahlia tubers must be overwintered frost-free, as they usually do not survive low temperatures. A cool and dark cellar with medium to high humidity is ideal for this.

From February you can prefer dahlia plants, which means that you can expect flowering as early as June. This is significantly earlier than those plants that are planted directly in the ground after the last frost. Another advantage of pre-cultivation: the plants are less susceptible to snails . The shoots are already strong and less attractive to the voracious animals. Another plus point is the reduced failure of the plants, as they form shoots more reliably.

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When preferring the dahlias in February, a suitable location is important. If it doesn’t fit, the shoots can grow stunted or they simply die.

location requirements

  • hell
  • Temperature around 15°C
  • frost-free
  • well ventilated
Note: If you do not reach the temperature of 15°C, you can prefer the tubers at at least 5°C. In this case, it takes longer for shoots to form, but they tend to grow less horny.

water tubers

One way to encourage flowers is to water the bulbs. However, soaking is not without controversy, since the dahlia tubers can quickly become oversupplied with water in a rainy spring. This method is therefore recommended for regions where there is little rainfall or for a pot culture where the plants can be protected from too much moisture. The method is also recommended if the tubers were too dry in winter and are severely shriveled as a result.

Instructions for watering

  • Examine tubers for health
  • remove damaged and diseased tubers
  • Fill bucket with lukewarm water
  • Soak dahlias in it for half a day

After watering, the plants are put in a cardboard box or in a wooden box in a suitable location. Check regularly for rot or mold.

Keep tubers warm

You don’t necessarily have to soak healthy and vital tubers. It is usually sufficient if you put them in a box in a suitable location to move them forward. With this method, always check whether pests settle on the plants. Aphids in particular find the first tender shoots extremely inviting. However, they can usually be washed off easily with a sharp jet of water.

set tubers

One way to grow dahlias is to plant them directly in the ground. This has the advantage that they are soaked indirectly by moistening the substrate.

Instructions for planting the tubers

  • remove damaged and rotten tubers
  • Fill the pot with an approx. 2 cm thick drainage made of expanded clay or lava granules
  • Fill in the substrate
  • Fill buckets with warm water
  • Soak tubers in it for a short time (about 1 to 2 hours).
  • Use dahlias
  • cover thinly with soil
  • Water the substrate well
  • spend in a warm, bright location

Remove excess water from the coaster about half an hour after watering. Check regularly how moist the soil is. To do this, do the finger test by drilling into the ground with your index finger. If the fingertip is wet, you don’t have to water. It is watered again only when the substrate feels dry.

If the shoots are large enough and there is no longer any threat of frost, the young dahlias can move outdoors.

The method of soaking the substrate reduces the risk of mold growth and overly damp tubers. These immediately form roots in the soil and can thus absorb nutrients better. Compared to other methods, you don’t have to feed on the tubers for so long. This usually leads to more vital and stronger plants.

Preculture in the cold frame

You can put the dahlias in a cold frame from mid- March . The cold frame is not only warm, but also very humid. You have the option of placing a small nursery over the tubers in the ground, thereby creating a greenhouse effect. As soon as the first shoots appear, you should air the cold frame regularly so that heat does not build up.

Tip: Only remove the cold frame when there is no longer any risk of frost.

frequently asked Questions

Do I have to divide dahlias before pre-growing?

If you want to propagate dahlia plants by division, you should do so once you have started propagating the dahlia tubers. As soon as the first small shoots appear, you can separate individual tubers with shoots from the mother plant. If you cut off the tubers beforehand, you do not know whether the tuber will certainly form a shoot.

When should dahlias that have been brought forward be fertilized?

During the pre-culture it is not necessary that you fertilize the plants. Once they are permanently outdoors, you can start fertilizing the plants.

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