Larkspur: planting, caring for & propagating

Larkspur is one of the absolute classics in the garden. Here you can find out everything you need to know about planting and caring for the popular perennial.

The Larkspur (delphinium) enriches every garden with its wonderful colors and its botanical name already suggests that the flowers of the delphinium resemble a dolphin. The tall ornamental plants are an integral part of many gardens - we explain what else you should know about these beautiful plants.

Larkspur belongs to the buttercup family (Ranunculaceae) and is one of the best known and certainly most beautiful perennials that we can put in our gardens. But what maybe not everyone knows is that the delphinium is a poisonous plant, because the contained alkaloids (elatin, delphinine and others) make the plants and especially their seeds extremely poisonous. This property even earned delphiniums the title of “Poisonous Plant of the Year” in 2015.

Larkspur: origin and characteristics

The various delphinium species come either from the Mediterranean or from Asia. Larkspur has erect stems that are sometimes branched. Wonderful single or double flowers then grow on these stems - making them an eye-catching ornament for your garden. With its wonderful flowers, delphinium is also ideal as a cut flower or for drying. Delphiniums come in white, pink, red, blue, and purple flower colors. These flower colors are of course available in a wide variety of color gradations and you can marvel at the blooming of delphiniums from June to August.

The delphiniums can vary greatly in size, because the smallest species only reach a height of about 20 centimeters. However, some delphiniums manage to grow to a height of as much as two meters. Of course, such an ornamental plant looks great in the garden, but it also means extra maintenance - such tall plants are always at risk of tipping over, especially in strong winds. You also have to be careful with the bed neighbors of delphiniums, because not every plant is suitable for it. Suitable neighbors for delphiniums are bluebells (Campanula lactiflora), irises (Iris barbata), daisies (Chrysanthemum max), cranesbill (geranium) or yarrow (Achillea filipendulina). It is even said that irises promote the growth of delphiniums. One should avoid, however, flame flowers (phlox) and asters (aster) in the vicinity of the delphinium, since the roots of these plants do not understand each other and damage underground.

Delphinium species

There are many different types of delphiniums, varying in size, color and area of ​​origin. In total there are an estimated 400 different species of delphiniums, most of which come from different parts of Europe. The delphiniums can be botanically subdivided or also according to the crossing types or hybrid varieties.

Larkspur: Botanical Distinction

• Garden Larkspur or Hyacinth Larkspur (Consolida ajacis)
• Field larkspur or field larkspur (Consolida regalis)
• Dwarf Larkspur (Delphinium grandiflorum)

As you can already see from the different species names, the system in the genus is the Delphiniums are very complicated and some of the species names have also changed in recent years changed. Such modifications come about through more precise methods of analysis, since there are kinships today through molecular biology among different plants can be determined more precisely than before, where the system was created solely on the basis of the appearance of the plants became.

In breeder circles, a distinction is made between the following delphinium species or delphinium hybrids:

• Elatum Group (Tall Garden Larkspur)
• Pacific group (Pacific garden larkspur)
• Belladonna Group (Half-tall Larkspur)

The wild delphiniums are usually only annual or biennial, whereas cultivated garden forms are often more long-lived. It is generally said that the taller a delphinium grows, the longer it lives. For example, Pacific strains only live up to three years, Belladonna strains can live up to five years, and Elatum strains even manage to live up to ten years.

Buy delphinium: you should pay attention to that

If you are at the nursery and would like to grow a new delphinium plant, there are a few things you should consider to ensure that you have the best possible plant to take home with you. So you should stay away from delphiniums that are already in full bloom in the nursery, because these plants will grow very poorly in your garden. It is of course very tempting to buy such a beautiful flowering delphinium plant, but you will not be very happy with it. Otherwise, you should of course - as with all purchased plants - also pay attention to the health of the plants, because after all you don't want to bring diseases and pests into the garden. It is therefore important that you make sure that there is no fungal coating on the leaves. You should also check the plants for pests. The eggs are often found on the underside of the leaves or you can see signs of feeding on the leaves. Therefore, always check each plant for damage, leaf discoloration, or other symptoms before purchasing.

Of course, when it comes to buying delphiniums, we cannot avoid Karl Foerster, who was a well-known gardener and perennial grower and grew countless wonderful delphiniums. Karl Foerster died in 1970, but his breeds survived him and of course you can buy them in many nurseries, including Foerster-Stauden in Potsdam-Bornim.

Plant delphiniums

Delphiniums need a lot of nutrients and therefore you have to move them again and again so that the soil is not leached too much. Below you will find a few points that you should consider when planting delphiniums so that you can enjoy the beautiful ornamental plants for a long time.

The perfect location for Larkspur

In order for delphiniums to grow optimally, they need a sunny spot in your garden where they are protected from the wind. However, the delphinium does not want to stand in the blazing sun, because it prefers the sun on its head and shade on its feet, as the saying goes. It is therefore advisable to place other low-growing ornamental plants around the delphinium that can provide shade. The delphinium prefers a loamy, humus-rich soil that should be nutrient-rich and deep, but low in nitrogen. So that a sown delphinium can germinate, it needs a cool soil temperature of 10 to 12 °C.

The correct procedure for planting delphiniums

Larkspurs can be sown outdoors either in autumn to mid-October or in spring in the months of March and April. You can also sow the delphiniums in boxes and pots indoors from the end of March and prefer them. This gives the plants a head start in growth and protects them from pests and diseases when they emerge. In addition, delphiniums that have been brought forward are also protected from frost events in this way, since they are not planted out until mid-May. You should keep a planting distance of 15 to 30 centimeters.

How do you properly plant delphiniums?

• Water the delphinium root ball before planting
• Dig a hole with enough room for the root ball
• Add fertilizer such as manure or compost to the planting hole
• Put the delphinium in the hole
• Make sure that the delphinium's root ball is flush with the surface of the earth
• Fill in the hole with the excavated soil
• Firmly press the soil around the delphinium
• Water the larkspur thoroughly

Maintain delphinium

So that you can enjoy your delphiniums all summer long, you should pay attention to a few things when caring for these plants. Due to their height, delphiniums are very susceptible to wind, which is why you always need a wind-protected place for them should look for your delphinium, otherwise there is a risk that it will snap or be blown over will. Optimum care also includes pruning delphiniums in summer. Once the delphinium has flowered, you should shorten the stems to 20 centimeters. The plant will rejuvenate and sprout again. You can therefore expect a second flowering in late summer. Pruning is also recommended to prevent delphiniums from growing very tall, because the taller the delphinium stalks are, the more susceptible they are to wind. Do not cut the delphinium deeper than 20 centimeters, otherwise it may no longer be able to sprout.

Water delphinium

Delphiniums must be watered sufficiently and regularly for optimal development, since delphiniums have a very high water requirement. If the weather is very hot and there are severe dry spells, you should water the delphinium at least once a day, if not twice. To avoid excessive water evaporation, you can spread a layer of mulch around the delphinium or create shade with ground-covering plants.

Fertilize delphinium

It is highly recommended to add some fertilizer such as compost to the soil before planting or sowing. Rotten horse manure is also particularly suitable for fertilizing delphiniums. Since the plants are shallow-rooted, you only need to put the fertilizer about 40 centimeters into the soil. It is advisable to fertilize perennial delphiniums organically twice a year, with it being ideal to fertilize organically once in spring before they sprout and once in autumn after pruning. Organic means, such as your own, are suitable for this compost, as fertilizer. You can also use ours Plantura organic flower fertilizer use to provide your delphinium with sufficient nutrients so that it survives the winter protected.

Compost, manure or other organic fertilizers should always be worked into the soil carefully, being careful not to damage the roots of the plants. The advantage of organic fertilization in autumn is that the fertilizer decomposes a bit can be unlocked, giving your plants a strong start next spring guaranteed. If you use mineral fertilizers for your larkspur, it is advisable to always pay attention to the instructions for use and especially to the dosage. You can find out more about this in our special article mineral fertilizers.

Breeding delphiniums

Larkspur sows itself if you let the infructescence fully mature. If you are not satisfied with this individual sowing, you can also use another variant. Nowadays, delphiniums are usually propagated by dividing the stick.

What is the best way to divide delphiniums to propagate?

• Dig up your delphinium
• Use a spade to divide the root ball
• Place the divided root ball in a bucket of water
• Dig a planting hole and loosen the soil in it
• Mix compost into the hole in the ground
• Place the delphinium in the planting hole as previously described

Delphiniums are divided in spring, April is best for this. In the best-case scenario, these larkspurs bloom in the same autumn or in the next spring and delight our eyes with their wonderful blooms. Of course, you can also propagate the delphinium from its seeds, which you can then easily sow again. You must not cut back the delphinium for this, you must let it wither so that the seeds can develop. It is important not to cut back delphiniums after the first flowering so that the seeds have enough time to ripen. It then develops follicles, which then contain characteristic triangular seeds. You can now collect these fruits when they have turned brown and are dry - but you must collect them before the fruits burst open and seed themselves.

If necessary, you should dry the collected fruit. The seeds must then be cleaned and stored in a dry and dark place. In spring you can then pull the seeds forward from March or sow them directly into the ground from May. If you propagate hybrid delphiniums yourself, the following generations will have different characteristics and their appearance will vary from the parent plants - but this allows you to add some diversity to your garden bring.

Larkspur overwinter

Larkspurs in the field do not need any special winter protection, apart from cutting them back in autumn and adding another dose of compost. This treatment is sufficient for perennial delphiniums so that they sprout again in spring. For annuals and biennials, you should either sow them yourself or collect the seeds.

However, plants grown in containers need protection to survive the winter. These are more sensitive and should be protected against frost as follows:

• Wrap the tubs with fleece
• Place the tubs in sheltered places, for example on a house wall or in corners
• Place the buckets on Styrofoam or wood to keep the cold off the ground
• Cover the plants with brushwood or leaves

Here you can find out more about Hibernation of different plants and about which of them can survive our winter without any problems.

Common diseases and pests in delphiniums

Our delphiniums are also repeatedly threatened by various animal pests. Especially often he is from snails (Gastropoda), miner flies (Agromyzidae) and Christmas mites (Tarsonemidae) affected. But some diseases also occur on delphiniums, such as bacterial blackening (Pseudomonas delphinii), powdery mildew (Erysiphaceae) or viruses. The occurrence of pests and diseases is often promoted by an unsuitable location - with delphiniums this is often too shady. You can use plant manure as a preventive measure to strengthen delphiniums. If the delphinium is attacked by fungi such as powdery mildew, you can simply cut off the affected shoots and thus contain the infestation.