Acanthus plants develop characteristic leaves whose shape has been used as a model for ornaments in decorative art. The perennials enchant various themed gardens. Anyone who takes a closer look at their requirements will enjoy the breathtaking blossoms for many years to come.
What is Acanthus and how to care for it in the garden?
Acanthus, also known as hogweed, is a genus of plants with 20 to 30 species that can be cultivated as ornamental plants in gardens. Its ornamental leaves and striking hood-shaped flowers, which appear in spiked inflorescences, are characteristic. Acanthus is hardy, prefers sunny locations and well-drained, nutrient-rich soil.
Origin
Acanthus is a genus of plants that belongs to the Acanthus family. It includes 20 to 30 species whose main distribution area is in tropical and subtropical climate regions. A few representatives are native to the Mediterranean and Asia. The species are also known as hogweed. But the plants have nothing in common with the Heracleum genus of the same name.
Four species can be considered as ornamental plants:
- Hungarian or Balkan hogweed (Acanthus hungaricus)
- Prickly Hogweed (Acanthus spinosus)
- True hogweed (Acanthus mollis)
- Syrian hogweed (Acanthus syriacus)
Growth
The plants are perennial and predominantly herbaceous. A few Acanthus species grow as semi-woody shrubs. They often develop underground rhizomes that are used for survival and vegetative reproduction. With the help of the runners, the plants form dense stands. The shoot axis grows prostrate or upright. The growth heights of the individual species vary greatly. They are between 30 and 150 centimeters.
leaves
The acanthus plants mostly develop opposite leaves. A few species have whorled or basal clustered leaves. In all species they are divided into a stalk and a blade. The leaves can be simple in structure. All four ornamental plants develop deeply cut, pinnate leaves with a smooth or toothed to thorny edge. They are reminiscent of oversized dandelion leaves and are called ornamental because of their distinctive shape.
Bloom
During the flowering period, Acanthus species become a real eye-catcher because their spiked inflorescences are covered in hood-shaped individual flowers. Its four petals are fused into a partially reduced upper lip and an enlarged lower lip, which ends in three blunt petal lobes. The flowers grow up to five centimeters long and are supported by two bracts that are armed with thorns. They surround the flower like a collar. The inflorescence reaches heights between 40 and 200 centimeters.
Flowering time
The flowers appear between June and August. They are whitish in color and often develop pinkish nuances. Some species have strong pink petals. Among the wild forms there are yellow, scarlet or blue flowering species.
Fruit
In autumn, numerous capsule fruits containing between two and four seeds appear on the inflorescences. When the fruit ripens, the capsules burst open explosively along pre-formed seams, so that the seeds are thrown out.
Usage
The plants are suitable for creating colorful perennial beds. Large species are at their best in single or paired positions. Lower ornamental plants harmonize in small groups. Because of their wild shape, Acanthus perennials fit perfectly into the natural garden. Because of the ornamentally shaped leaves, the plants harmonize with stone walls, water basins or next to stone steps on terrace slopes. Since the parent species of the ornamental plants come from the Mediterranean region, they are suitable for designing Mediterranean gardens. They add color accents to stone structures.
These plants go well with Acanthus:
- Catnip (Nepeta)
- Yarrow (Achillea)
- Iris
- Sea kale (crambe)
- Stuffed Gypsophila (Gypsophila paniculata)
Is Acanthus poisonous?
Acanthus species are not poisonous and can be planted in the garden without hesitation. Many species are used in natural medicine. They relieve coughs and help with respiratory diseases, flu and colds. Extracts of the plant parts are used externally for gout, sprains or bruises. Ointments promote the healing of burns and wounds.
Which location is suitable?
The species, which come from the Mediterranean region, prefer locations on scree slopes and in stony terrain. Plants from tropical climates require wetter locations. All ornamental plants thrive in sunny locations. They tolerate partially shaded locations.
What soil does the plant need?
Cultivated Acanthus species feel comfortable on a well-drained substrate with nutrient-rich and deep properties. They like fresh floors. Short periods of drought do not cause them any problems. A slightly loamy soil that can retain moisture is ideal. If water accumulates in the substrate, the roots will rot quickly.
The correct planting distance
Before planting, please note that the perennials can grow to considerable size. Low-growing companion plants are quickly crowded out. Place Acanthus in the bed at a distance of at least 70 centimeters from neighboring plants. There should be no more than two copies per square meter.
Propagate Acanthus
In the spring you can propagate hogweed by division. Divide the excavated rhizome into several pieces so that each root piece has sufficient fine roots and shoots.
Acanthus species can also be propagated via root cuttings. In autumn, cut a rhizome into pieces about eight centimeters long and place the cuttings in a mixture of sand and peat. The substrate is covered with a two centimeter thick layer of soil and moistened. Store the vessel in a cool place. As soon as the first sprouts appear, the pot is placed in a bright location.
Sowing
Immediately after flowering, you can harvest the immature capsules and store them in a sealed container. Here the seeds continue to ripen until the fruits burst open. The seeds are scattered on potting soil between November and March and lightly covered with soil. The seeds of the Acanthus species are dark germinators.
The substrate should be kept slightly moist for the next two to four weeks. Place the planter in a bright place with temperatures between 18 and 22 degrees Celsius. After this phase, the seeds need a cold stimulus to stimulate germination. The pot is placed in a cool place for the following four to six weeks. Here the temperatures should be between just below zero and four degrees. It can take up to ten weeks for the cotyledons to appear.
Acanthus in a pot
The plants develop tap roots that extend deep into the soil and require a lot of space. Acanthus thrives in deep pots that have adequate drainage. Don't choose a pot that's too big, but replant your Acanthus in slightly larger pots every year.
Since the perennials love warmth, they are perfect for cultivation in raised beds as long as their longitudinal axis is aligned north-south. The vertical wooden walls make optimal use of the sunlight in the morning and afternoon.
This is what pot plant soil is made of:
- coarse grains for a loose structure
- ideally suitable: lava grit, expanded clay or gravel
- loamy components for water storage
Balcony
Acanthus feels particularly comfortable in a pot on south-facing balconies with airy conditions. Container plants should be watered regularly and thoroughly during the summer months. The perennials enjoy watering once a week.
Watering Acanthus
Keep the substrate slightly moist. Acanthus enjoys moderate watering. The perennial tolerates slight drought well. Waterlogging should be avoided so that the roots do not rot.
Fertilize Acanthus properly
Occasionally give the perennials plant broth via the irrigation water. They strengthen vitality and make Acanthus more resistant to diseases and pest attacks. In spring you can incorporate some rock dust or compost into the substrate. No further fertilization is necessary.
Cut Acanthus correctly
The inflorescences remain standing over the winter. They are stable and are a real eye-catcher during the gray season. In spring the perennial is cut back close to the ground. The inflorescences can be placed in vases as cut flowers.
How do I transplant correctly?
Ingrown Acanthus perennials can be removed from their location with a lot of effort. Since the roots reach deep into the soil, the rhizomes are divided when transplanted. If you want to remove the perennials from a location, you must regularly dig up newly sprouting rhizomes. Choose the location carefully before planting. Acanthus develops splendidly if it grows undisturbed in one location for several years.
hardy
Although the species is considered hardy, winter protection is advisable. A thick layer of bark mulch and straw or spruce and fir branches protect the rhizome from frostbite. In snowy regions, the plants are optimally protected by a closed snow cover.
Potted plants should be placed on an insulating base. This can be a Styrofoam plate or a piece of wood. The pot is wrapped with fleece, jute or plastic film so that the substrate does not freeze. A rain-protected location prevents the substrate from becoming waterlogged. You can also overwinter potted plants indoors. Place the bucket in an unheated room.
Fungal infestation
Acanthus is occasionally attacked by powdery mildew. The fungal spores spread in dry and warm conditions. They colonize weakened or diseased plants and leave a wipe-off coating with a flour-like structure on the leaves. The risk of infestation can be reduced with a layer of mulch. It ensures constantly moist conditions in the substrate and increases the air humidity.
Acanthus does not bloom
While the Hungarian hogweed blooms reliably every year, its three related ornamental plants often show irregular flower development. If the perennials don't bloom, a harsh winter may be the cause. Ground frost causes the rhizome to freeze back and partially die. The damaged rhizomes sprout reliably, but the young plants need two to three years until the first flowers. The underground parts of plants can be protected with winter protection.
Tip
All four ornamental plants can be distinguished by their leaves. The flowers are very similar. When purchasing, pay attention to the foliage if the variety has not been assigned to a parent species.
Varieties
- Hollard's Gold: Acanthus mollis hybrid with white to light purple flowers, blooms between July and August. Up to 120 centimeters high.
- White Lips: Acanthus hungaricus hybrid with white crown and purple bracts, blooms from June to August. Up to 70 centimeters high.
- Mornings Candle: Hubris from Acanthus mollis and spinosus. White flowers with purple bracts. Flowering period from July to August. Growth height up to 100 centimeters.
