Dahlias (Dahlia) are sensitive to cold and can overwinter in a pot in a frost-free place. With the right instructions, this is still easy to do and the flowers are guaranteed in the following year.

In a nutshell

  • Outside of mild regions, dahlias must be wintered frost-free in pots
  • timely fertilization
  • increase soil moisture at the right time
  • cut back early

preparations

Good preparation at the right time is important for the optimal overwintering of dahlias, because this increases the chances of lush flowering in the following year. The preparations look like this:

  • End of August: last time to fertilize
  • Beginning of September: cut off old and withered plant parts
  • from October until the first night frost: to make digging up easier, keep the soil evenly moist until ready to dig up
  • generous pruning

An additional pruning is immensely important for dahlias because it saves energy for shoot and flower growth and this is stimulated by the measure. This should be noted:

  • always wait for the first night frost
  • select a dry, frost-free day
  • pull out frozen ones or cut them close to the ground
  • Shorten all shoots to five to six centimeters above the root neck
  • remove all but the three strongest shoots from weakened/“blooming lazy” specimens
  • Let the rootstock rest for a week before digging the bed (not necessary if temperatures consistently fall well below freezing and the tuber threatens to freeze)

Dahlias that are already cultivated in the pot and are only moving to a suitable winter quarters together with them should also be shortened. But that happens before the first frost. Because they feel the cold more intensely in the pot, they should be moved to winter quarters at five degrees Celsius at the latest.

Excavate: Instructions

Utensils needed:

  • watering can or garden hose
  • rake
  • digging fork
  • Paint brush or root brush

Method:

  • loosen superficial soil with a rake
  • water the soil well
  • push aside the first layer of earth with a digging fork
  • Insert a digging fork at the side of the rootstock and lever it up
  • Remove the soil from the roots as best as possible with a brush or swab

root control

Very rotten, moldy or badly damaged roots are not suitable for wintering. For this reason, the roots should be examined for this before potting. In the event of slight root damage, these must then be cut out. In the case of weakly flowering specimens, the root tips are minimally shortened. When cutting, it is essential to use a disinfected and sharp cutting tool. Cut wounds should then be sealed with charcoal ash or wax.

Potting: Instructions

  • Pot size: Roots must find space in it without kinking
  • Planting depth: as for bed planting
  • If there are several rootstocks/tubers in one pot, avoid touching
  • Substrate: normal potting soil or substrate with little or no nitrogen content
  • Addition: a handful of sand or clay granulate supports good permeability
  • insert plant
  • Cover the shoot buds on the tuber shaft only lightly with soil

Tip: If you label the respective containers with plant details, you will know next spring which dahlias will overwinter in the pot. This is particularly helpful if you are planning to rearrange your plants and/or if you need matching color combinations.

location

When it comes to overwintering dahlias, the right location is important. This should meet the following criteria:

  • ideal ambient temperature: between 5 and 8 degrees Celsius
  • no cold drafts
  • Light conditions: the darker, the better - brightness disturbs the resting phase during the cold - can lead to poor flowering
  • Avoid dry air (boiler rooms or locations with switched on radiators are therefore unsuitable)
  • Excessive humidity promotes rot (laundry rooms with dryers are therefore not recommended)
  • Optimal locations, for example, attic, unused and unheated party room, windowless garden shed or dark storage room

Tip: If a dark location is not available, wrap the pot completely in newspaper. Poke small holes in it for air circulation.

care in winter

When dahlias hibernate, there is still a certain need for care. They need to be dusted regularly so they can breathe and not die of asphyxiation.

Occasional checks for rot or mold are also advisable. This is usually done with a smell test, because the earth then smells musty. Mold formation may also be visible on the surface of the earth. In addition, the soil should never dry out completely.

end of hibernation

From the end of February/March, dahlias slowly wake up from "hibernation". It's still too cold outside to put them outside. When it starts to get warmer from the middle/end of April, they can go outdoors again. If there is still frost, they can usually handle it well and take no damage. If you want to be on the safe side, wait until after the ice saints in mid-May to plant them in the bed.

frequently asked Questions

Can Dahlia Tubers Be Prepared?

Yes, that is possible from March, when a new season year begins for them. To do this, put the tubers in a pot with normal potting soil. It should be about two inches covered with soil. Then choose a cool spot in a bright spot and water gently.

Do you always overwinter dahlias in pots?

No, you can also overwinter the dahlia tubers in boxes or similar containers. Fill them with sand or leaves. Spray the sand and foliage minimally with water beforehand. This protects the tuber from drying out. It is important that the pure tubers of the dahlias have a dark and cool place to hibernate - as with pot hibernation.

What happens when dahlias are dug up too early?

In this case, the storage process of nutrients and energy is not yet complete as long as the stalks remain green. This in turn changes with the first night frost at the latest. If you dig up dahlias too early for the winter, there is a high probability that insufficient supplies of nutrients and energy will hang up the new shoots.

Category:

Garden plants