A poisonous beauty that has been a constant companion in cottage and perennial gardens for centuries and delights the silent observer with its lush flowers: we are talking about delphiniums, a member of the buttercup family. Larkspur is a herbaceous plant, which is why it does not become lignified and dies after each vegetation period in order to sprout again in spring. Whether the perennial plant is annual, biennial or even perennial depends on the Delphinium variety planted. As a rule, the popular buttercup plant takes care of its own sowing and is also – when planted outdoors – resistant to our winter temperatures. The active ingredients of delphiniums were already used as a medicine in ancient times and still make many a gardener’s heart beat faster with their distinctive blossoms.
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A loamy-sandy, slightly alkaline soil, enriched with humus and a sunny spot – these are the preferences of the delphinium. To prevent the soil from drying out quickly, it is advisable to provide shade at the foot of the delphinium. Groundcover or other low-growing plants are often suggested. However, if you want to use it, you should note a few important points:
- The plants in the direct vicinity of the larkspur must have the same requirements in terms of fertilizer, watering and location as the larkspur.
- In order not to destroy the roots of the large buttercup plant, the neighboring plants should be planted at a sufficient distance.
- A planting distance of at least 30 cm from the large delphinium is ideal.
- Due to the expected growth height of the perennial, the plant needs a wind-protected location or has to be secured with support rods or trellises.
sowing and planting
From May to September, the light germinator can be sown directly in the garden. Those who prefer to be on the safe side prefer the plants indoors and plant them outdoors from mid-May.
Depending on the variety, delphiniums can reach a height of between 70 cm and 2 m. It is therefore particularly important to keep a minimum distance of 1 m between the individual plants. You can prick out early seedlings from a size of 15 cm.
Companion plants, among which the members of the Delphinium come into their own are, for example, feverfew, cranesbill, lupins, lady’s mantle and sage. Other perennials are also suitable, provided they grow low and are planted at a certain distance from Delphiniums.
It is possible to keep Delphinium plants in tubs, but this can lead to poorly developed flowers and stunted plants. To counteract these factors, fertilizing and the right cut is even more important than in conventional garden planting. A special clay granulate helps the potted plants and the gardener to provide the plant with enough nutrients and water. As a rule, however, a humus-rich soil with a high proportion of clay and sand is used in the buckets. In the spring, the delphinium can also be divided here and distributed to other pots. However, the implementation in a prepared garden bed is also possible without further ado. Larkspur, which is normally hardy, needs special attention as a container plant in the cold season and must be kept protected.
watering and fertilizing
In order to develop the full bloom, the delphinium has a very high water requirement. As with many other plant species, however, waterlogging promotes diseases and causes lasting damage to the plant. Properly and sufficiently watered, the flowering plant survives even higher summer temperatures unscathed.
- water early morning and late afternoon in midsummer.
- Do not wet leaves and flowers with water.
- Avoid waterlogging.
- Remove rotting plant remains from the roots before watering -> risk of mold growth.
In spring and autumn, the flowering plant needs nutrients in the form of fertilizer. Horn shavings, grass clippings, stone dust or compost are carefully worked into the soil all around.
Less is often more: too much fertilization damages the plant, leads to oversaturation with nutrients and promotes cracks and fungal diseases due to excessive plant growth.
The delphinium likes to spread itself if the withered stands are not removed in time. If you want to sow in a targeted manner, remove the seeds in autumn and put them in pots from March. The chances of germination are significantly higher with this method. The seed is only lightly pressed into the ground, because the plants are light germinators. For this reason, the seed should never be covered with soil. The germination period is about 10 to 16 days.
Another way to propagate the hardy plant is by division. For this purpose, the root of the delphinium is divided with a sharp spade in the spring and then put back into the prepared planting holes:
- Cut out a large planting hole and loosen the soil.
- Place plant roots in a water bath for a few minutes.
- Put the delphinium in the prepared hole and fill it with a compost-soil mixture.
- The top of the root ball must be just below the surface.
- Press the soil down lightly and water well.
There may always be reasons why a delphinium has to leave its old location. As a rule, this is not a problem if the following points are observed:
- Do not transplant during flowering.
- The project is ideal in spring, in late autumn or after pruning.
- Choose a suitable location with the required soil conditions.
- Generously cut out the delphinium.
- Do not place the plant deeper than it was previously covered with soil.
- Enrich soil with humus and loosely cover the root ball.
- Water a lot in the first few weeks to make it easier for the buttercups to grow.
In order to be able to enjoy the full splendor of the flowers, the delphinium also needs a cut at certain times.
- After the first flowering in June or July, cut the plant back to around 10 to 15 cm.
- Bend over the hollow stalks to protect them from moisture.
- Cut off the delphiniums close to the ground in autumn after the second bloom.
After the first cut, the plant will sprout again, but the flowers may not be as lush as before.
Cultivated outdoors, Delphinium is absolutely hardy. Only the roots of the species planted in tubs run the risk of frostbite. Here the delphinium should be covered with plenty of compost and the plant pot should be covered with sacking for safety. Incidentally, for older potted plants, a safe place on the wall, on the balcony or in the vestibule is sufficient.
diseases and pests
Annoying diseases and unwelcome visitors can often damage the flowering plant considerably.
- Long periods of cold during the growth period may promote bacterial blackening . The upper side of the leaf bulges slightly while the leaf itself turns black and dries up. Affected plants must be completely removed and destroyed. Treatment, for example by eliminating the infected regions, is not possible.
- Snails are absolutely infatuated with the young shoots of delphiniums and literally love to eat them. There are many tricks against the greedy robbers to get hold of them or to keep them completely away from the plants. One possibility, for example, would be to regularly collect the pests. Beer traps or sprinkling sawdust around the delphinium have also proven helpful.
- Powdery mildew is also common on the plant. Signs of infestation are reflected in white spots on leaves, buds dry up and fall off. A regular water supply and resistant delphinium species can prevent powdery mildew. In the case of already infected plants, the affected regions must eventually be removed. If you don’t want to resort to chemical agents, spray the delphinium every one or two days with a mixture of nettle or horsetail broth.
- Excessive moisture can encourage downy mildew infestation. Whether long periods of rain or incorrect watering, both damage the delphinium. The fungus can be identified by light spots on the upper side of the leaf and a gray to grey-purple, felt-like coating on the underside of the leaf. Here, too, the leaves and infested parts of the plant must be completely removed and composted.
- Another pest is the blue delphinium aphid . Various regions of the plant stick together with the excretions of the unwelcome visitors, the young shoot tips of the affected buttercup family curl up and die. A suddenly occurring ant population around the delphinium can also indicate aphids. In the early stages of infestation, hosing down hard with water is enough, but this can also have a negative effect on the blooming splendor. Soft soap and regular spraying with nettle juice or black tea have also proven their worth. Immediately remove and destroy heavily infested leaves and buds. If you have the opportunity, you should settle natural enemies such as ladybugs and lacewings around.
- Stunted shoot tips, noticeably deformed leaves and mottled flowers can be an indication of the soft skin mite . Due to their size, these small arachnids cannot be seen with the naked eye and feast on the sap of the infested host plant. Predatory mites can be used to combat these pests, but acaricides can also be used in the event of a heavier infestation. If you want to do without chemicals completely, you can rely on the natural predators of the soft skin mites and completely remove heavily infested parts of the plant.
Tips and tricks for caring for delphiniums
- If you want to prevent self-seeding, remove the withered inflorescences immediately.
- Many diseases, such as the notorious bacterial blight, can be prevented by buying robust varieties of delphinium.
- Regular hosing down with horsetail decoction can prevent infestation with mildew fungi.
- Some delphinium species do not tolerate fertilization with sawdust. Use a different type of fertilizer for these varieties.
- If there is a risk of storms, tie the plants together or secure the larkspur in advance with wooden supports.
- Asters and phlox plants are unsuitable for socialization. Their root growth damages those of the delphinium underground.
- Protect young shoots from slugs. Whether with slug pellets or natural means is left to the preference of the gardener.
- Acidic soils need enrichment with lime in the spring.
- Avoid underplanting trees. Larkspur takes care of the shade.
- The radical, ground-level cut in autumn prevents disease and pest infestation.
The popular buttercup plant is not just an ornament for old cottage gardens. Despite the increased maintenance effort for the different varieties of Delphinium, every gardener can cultivate the perennials without any problems. Larkspur is particularly effective in perennial beds or rose beds due to its tall growth and colorful flowers. With the right cut, the perennial plants bloom until the beginning of October – a blaze of color for the autumn garden.