table of contents
- Preparations
- Digging out: instructions
- Potting: Instructions
- Location
- Care in winter
- End of wintering
- frequently asked Questions
Dahlias (Dahlia) are sensitive to cold and can overwinter in a frost-free place in the pot. With the right instructions, this can still be done easily and the blooms in the following year are guaranteed.
In a nutshell
- Outside of mild regions, dahlias must be overwintered frost-free in pots
- Stop fertilizing in good time
- Increase soil moisture at the right time
- cut back early
Preparations
For the optimal wintering of dahlias, good preparation at the right time is important, because this increases the chances of lush flowering in the following year. This is what the preparations look like:
- End of August: last fertilization time
- Beginning of September: cut off old and dry parts of the plant
- From October until first night frost: to make excavation easier, keep the soil evenly moist until excavation
- generous cut back
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 food or cut off near the ground
- Shorten all shoots to five to six centimeters above the root neck
- In the case of weakened / “blooming rotten” specimens, remove all shoots except for the three strongest ones
- Let the rootstock rest for a week before excavating the bed (not applicable if temperatures should continuously fall well below freezing point and the tuber is in danger of freezing)
Dahlias that have already been cultivated in pots and are only moving to suitable winter quarters with them should also be shortened. But that happens before the first frost. Because they feel the cold more strongly in the pot, they must be moved to winter quarters from five degrees Celsius at the latest.
Digging out: instructions
Required utensils:
- Watering can or garden hose
- rake
- Digging fork
- Painter's brush or brush
Method:
- loosen the surface soil with a rake
- Water the soil well
- Push aside the first layer of soil with a digging fork
- Pierce the digging fork at the side of the rootstock and lever it up
- Remove the soil from roots as best as possible with a brush or tassel
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 case of slight damage to the roots, these should then be cut out. In the case of weakly blooming specimens, the root tips are minimally shortened. It is essential to use a disinfected and sharp cutting tool when cutting. Cut wounds should then be closed with charcoal ash or wax.
Potting: Instructions
- Pot size: There must be room for roots in it without kinking
- Planting depth: as when planting beds
- Avoid contact if there are several roots / tubers in one pot
- Substrate: normal potting soil or substrate with little or no nitrogen content
- Addition: a handful of sand or clay granulate supports good permeability
- Insert the plant
- Cover the shoot buds on the tuber shaft only lightly with soil
Tip: If you label the respective vessels with plant details, you will know in the coming spring which dahlias will overwinter in the pot. This is especially helpful if you are planning to redesign your plants and / or if you need suitable color combinations.
Location
When wintering 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 inadequate flower formation
- Avoid dry air (heating rooms or locations with switched on radiators 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 cellar
Tip: If a dark location is not available, wrap the pot completely in newspaper. Small holes have to be pierced to allow air to circulate.
Care in winter
When dahlias hibernate, there is still a certain need for care. They should be dusted regularly so that they breathe and do not fall victim to suffocation.
Occasional tests for rot or mold are also advisable. This is usually done via an odor 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 wintering
From the end of February / March, dahlias slowly wake up from their "hibernation". It's still too cold outside to put them out. When it starts to get warmer from the middle / end of April, they can go back into the open air. Should there still be frost, they can usually handle it well and will not be harmed. Those who 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
Yes, that will be possible from March when a new season begins for you. To do this, put the tubers in a pot with normal potting soil. It should be covered with soil about two centimeters. Then choose a cool location in a bright place and water gently.
No, you can overwinter the dahlia tubers in boxes or similar containers. Fill this with sand or leaves. Spray the sand and leaves with minimal water beforehand. This protects the tuber from drying out. It is important that the pure bulbs of the dahlias are dark and cool for wintering - as with the wintering in pots.
In this case, the process of storing nutrients and energy is not yet complete as long as the stems remain green. This in turn changes with the first night frost at the latest. If you dig up dahlias too early to overwinter, there is a high probability that insufficient supplies of nutrients and energy will affect the new shoots.
