Hibernate dahlias – care in winter

They enrich every garden with their blossoms and colors, from summer to late autumn. They are the divas among garden beauties. If you give them enough attention in the form of regular care, they will reward you with an enchanting splendor of flowers. We are talking about dahlias, the popular bulbous plants that reach a height of up to 160 cm. There are more than 20,000 varieties worldwide, so there really is something for every taste. The dahlia has long since shed its reputation as an old-fashioned plant, because no nature lover can escape its magnificent charisma. To ensure that dahlias survive the winter well and continue to delight the gardener with their display of colors next year, a few important care tips must be observed.

Dahlias hibernate safely from September

Dahlias usually bloom from July to October. During this time, sufficient watering is essential for the plants to survive, ideally in the morning and in the evening. The fresh water should be given to the dahlia from below, even if it is more convenient to simply hold the water hose over the bed. The flowers and leaves of the dahlia do not tolerate watering in direct sunlight. From September, however, watering with fresh water should be slowly reduced. This measure encourages the tuber to store more water in order to survive the coming winter. As soon as the first frost is announced, the hobby gardener should take action and prepare the dahlias for the winter.

  • Color code dahlias if they are to be planted sorted in spring.
  • Cut the plants down to 5 to 6 cm.
  • Carefully dig up the tubers.
  • Examine dug up tubers and cut out rotten spots.
  • Disinfect injured areas with charcoal powder.
  • If possible, air dry tubers to prevent rot.
  • Leave some soil on the tubers.

The color marking of the dahlias is necessary because the first frost already turns the flowers uniformly brown-yellow, otherwise the choice of color next spring becomes a guessing game. Under no circumstances should the stems of the dahlias be cut flush. The reason for this is that the dahlia’s eyes do not come out of the tuber, but out of the stems. Experienced gardeners use a digging fork when digging up the tubers before winter, because you can use them to pierce the ground further away from the tuber, which significantly reduces the risk of injury to the plant.

The ideal winter quarters

When the dahlia tubers have dried, they can move into their winter quarters. Dahlias feel most comfortable in a dry room at a temperature of 5 to 8 degrees Celsius to overwinter here. This can be a basement room, a storage room in the house, the conservatory or the bedroom. The main thing is that no frosty temperatures can develop where they are kept, because then all the efforts for a sheltered winter would be in vain.

  • Store dahlia bulbs side by side to avoid mold.
  • If necessary, cover the tubers with peat dust.
  • Wooden boxes are particularly suitable for overwintering.
  • Tubers can overwinter well in sand and sawdust.
  • Turn the tubers at regular intervals.
  • Check regularly for pests.

preparations in spring

Anyone who has put so much effort into protecting the dahlia tubers over the winter should not get impatient when the first rays of sunshine herald spring. The dahlia tubers must be carefully prepared for their move into the garden so that they can show off their full splendor in the new year. From March you can bring them forward after the long winter. To do this, they are planted in a pot and placed by the window in a cool room. Now they do need water; but this should be used sparingly.

While the dahlia tubers are slowly getting used to daylight and sunlight again, the hard-working hobby gardener can use the time and professionally prepare the soil of the beds after the long winter. Deep digging should be avoided in any case, as this would destroy the valuable frost that has formed in winter. It is quite enough to loosen the top layer of soil with a rake where the tubers will be planted after wintering. Fortunately, dahlias show almost no soil fatigue after the winter. This means that you can often plant the same bed with the gems for years. Provided, of course, that the soil has been properly prepared and sufficient fertilization is provided after the winter.

  • Dahlias prefer a sunny location.
  • Waterlogging cannot form in sandy soil.
  • The planting site should be protected from the wind as much as possible.
  • Depth of the planting hole about a spade length.
  • Split the dahlia bulbs by hand or with a knife.
  • Too many tuber parts prevent new shoots.
  • Use a support rod from a growth height of 50 cm.
  • Cattle dung and horn shavings are suitable as fertilizer.
  • Add fertilizer to the planting hole first.
  • First insert the stake and then the tuber.

Dahlia tubers can develop best if they are planted in the ground so that the tip of the old tuber is just sticking out of the ground. To be on the safe side, you can spread a thin layer of mulch over it in case the ground freezes again. Bamboo or wooden stakes are particularly suitable as a support for a dahlia. But iron bars can also be used. It is important to note that the rod is first inserted into the ground and only then the tuber.

After about 3 weeks it is time to tie the dahlia for the first time. If you want to get particularly bushy plants, regularly pinch off the growth points during the growth phase, as well as the flowers that have bloomed. Chemical bombs can be safely dispensed with when fertilizing. These drive the dahlia up quickly thanks to the high nitrogen content; but the shoots are thin and weak. If cattle manure or horn shavings are placed directly in the planting hole, they give the dahlia the strength it needs to develop its full splendor and withstand even a stronger gust of wind.

Effective pest control

These diseases and pests are most common in dahlias:

  • leaf spot disease
  • mildew
  • Verticillium Which
  • aphids
  • red spider
  • nudibranch
  • Ohrenkneifer
  • caterpillars

So that after all the effort to get the dahlia tubers safely through the winter, the unloved pests do not immediately attack the young plants, some effective tools have proven themselves. Green soap, also known as soft soap, works wonders against aphids. Earwigs love dahlias more than anything. They are best kept away if they cannot find a hiding place, such as hollow stumps or tall plant stakes. Dahlias are a real treat for leaf bugs. Abundantly watered dahlias have been shown to be spared from these wolverines. The various pesticides do not always help. Then you should not just simply dispose of all infested parts of the plant, but burn them. This way you don’t give the spores a chance to strike again. The nuisance most hated by amateur gardeners, however, are the slugs, which have driven so many proud dahlia growers to despair. Winning the battle against these persistent pests requires a focused strategy:

  • Rake snails out of the ground after winter.
  • Create habitats for snail enemies such as hedgehogs, birds or frogs.
  • Create boundaries of lime, wood ash or sawdust.
  • Build a snail fence.
  • Set up beer traps inside the snail fence.
  • Set up hiking barriers made of sharp-edged gravel or chopped straw.
  • Liverwort preparations spoil the appetite of slugs.

Experience has shown that a snail fence is the most successful measure. They are made of concrete block, metal or plastic. As a 15 cm to 20 cm high barrier with sharp edges, the fence only keeps the slugs out if there are no gaps in between. In addition, it should be at least 5 to 10 cm deep in the ground. In addition, adjacent plants must not be able to be used as a bridge.

As successfully as the snail fence fulfills its task, this unfortunately also applies to useful animals such as hedgehogs, ground beetles or toads. The beer traps should only be used if the beds to be protected are surrounded by a snail fence. Otherwise they serve more as an invitation to the slugs on the neighboring properties. As much as the manufacturers of snail fences try to be aesthetic, these barriers are not beautiful to look at and detract from the attractive appearance of the dahlias. Therefore, a hiking barrier could be a possible alternative, which should be set up as soon as possible after winter.

Hobby gardeners and nature lovers who heed these tips will enjoy their dahlias throughout the beautiful season. By the time the next winter arrives, their experience will have increased even further and overwintering dahlias will gradually become routine.

Kira Bellingham

I'm a homes writer and editor with more than 20 years' experience in publishing. I have worked across many titles, including Ideal Home and, of course, Homes & Gardens. My day job is as Chief Group Sub Editor across the homes and interiors titles in the group. This has given me broad experience in interiors advice on just about every subject. I'm obsessed with interiors and delighted to be part of the Homes & Gardens team.

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