Plant, cultivate, propagate and more

Plant knapweed correctly

Ideally, knapweeds that were grown behind glass in February or bought ready-made in the garden center should be planted in the bed from the end of April. Another planting date is late summer, when the earth has warmed deeply. As long as you prepare the humus-rich, nutrient-rich soil in a fine, crumbly manner in the sunny location, soak the root balls of the young plants that are still potted in water. This is how the work continues:

• Dig small pits 30-40 cm apart, big enough for a root ball
• Enrich the excavated soil with compost, horn shavings, bark humus or guano granules
• One knapweed repot, position in the middle of the hole and plant up to just below the first pair of leaves
• watering and mulch with leaves, bark mulch or grass clippings

The wild perennial character of a knapweed comes into its own in a rustic clay pot. Use common ones potting soil based on compost as a substrate and add a handful of sand. Place some potsherds over the opening in the bottom of the pot as drainage.

care tips

The care program for a knapweed is knitted in such an uncomplicated way that even beginners among hobby gardeners can handle it without any problems. All important aspects at a glance:

• Water regularly when dry
• Fertilize every 4 weeks in beds and every 2 weeks in pots during the vegetation period
• Clean up withered and faded areas promptly
• Cut back close to the ground after the first flowering period

Cut back the perennial once more in autumn or late winter; this time up to 10 cm above the ground. Since the knapweed is completely hardy, there is no need for winter protection.
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Which location is suitable?

If a sunny to full sun location in the garden is to be occupied, the knapweeds are on hand as busy permanent bloomers. The summer perennials show their most beautiful side in the deeply humus-rich and nutritious soil, which is often fresh, moist and calcareous.
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What soil does the plant need?

The knapweed expresses its inimitable wild perennial character wherever the soil is humus-rich, loose and nutrient-rich. A slight lime content is just as welcome as fresh soil moisture without the risk of waterlogging. Nevertheless, the robust perennial also tolerates a sandy-loamy soil as long as there is a rich stock of microorganisms.

When is flowering time?

The knapweed shows off its distinctive fringed or tufted flowers from May to July. If you can't get enough of the pretty summer shrubs, cut the withered flowers close to the ground after the first flowering period and spoil them with a portion of compost. Then the floral ambassadors of summer lightness get a run-up for another performance on the garden stage.

Cut knapweed correctly

To successfully cultivate a knapweed, counts secateurs to the indispensable equipment. We have compiled all the occasions when the perennial is cut for you here:

• Cut stems that have just blossomed except for at least two leaves for the vase
• Clean out wilted flower stalks as soon as possible to make room for further shoots
• After the first flowering period, cut back to the ground for a late summer rebloom

The scissors are used for the last time in the season in autumn. Now cut the knapweed down to 10 cm above the ground. If you want to give the natural perennial enough time to sow seeds, move the pruning date to February.

Water knapweed

The knapweed shows little tolerance to drought. Therefore, do not let the perennial thirst. As soon as the soil has dried in the upper area, it is watered. Ideally, avoid overhead irrigation to avoid damaging the pretty bloom. With the can spout, the water is poured directly onto the root area.

Fertilize knapweed properly

It is by no means one of the ascetics among summer perennials. In addition to a balanced water balance, the knapweed also requires a regular supply of nutrients. Fertilize the summer flower from May until the end of the flowering period in the bed every 4 weeks with compost and horn shavings or plant manure. In the pot, the cheeky flower beauty thanks you for the administration of liquid fertilizer every 14 days.

Diseases

Hobby gardeners rarely have to complain about plant diseases on a knapweed. If there are problems, the ubiquitous fungal infection is usually the cause mildew behind. If you notice the first signs of mealy-grey coating on leaves and shoots, fight it with fresh milk. Water and fresh milk are mixed in a ratio of 9:1 and applied with a hand sprayer every 2-3 days.

hibernate

After the knapweed has pulled in its plant parts above ground or these have been cut off, frosty temperatures cannot damage the root ball. The strongest species can withstand temperatures as low as – 45 degrees Celsius. Even less robust breeds still stand up to winter temperatures of up to – 28 degrees Celsius. Protective measures are therefore unnecessary.

Multiply knapweed

Where the knapweed has established itself in the garden, there are three uncomplicated methods of propagation. The following overview shows how you can grow more specimens of these charming fringed heads in no time at all:

• Division of the root ball in spring or autumn
• Removal of root cuttings in summer to root them in the pot
• sowing of seeds behind glass from February

If you know how to keep pecking birds and voracious pests away from a seedbed, sow directly outdoors in September. You can then look forward to the first flowering of seedling-propagated knapweed in the second or third year after sowing.

Is knapweed poisonous?

Although Greek mythology tells of the centaur Chiron using a flower of the genus Centaurea to heal Achilles' foot wound, the knapweed has no healing powers. Likewise, there are no toxic ingredients in flowers, leaves or seeds. The flirtatious perennial is thus called for cultivation in the family garden.

Beautiful varieties

• Grandiflora: The cornflower-blue flowers draw a picturesque picture in beds and pots; Growth height 40 cm
• Major: The fluffy flower balls shine in violet-pink towards the sun; Growth height 70-80 cm
• Jordy: The variety impresses with its extravagant flowers, the edges of which thrive particularly frayed; Growth height 30-40 cm
• Alba: A top-class mountain knapweed with pure white flowers from May to July; Growth height up to 80 cm
• Carnea: An enrichment for the fragrance garden, because the light pink fringed flowers smell of peach; Growth height 40-50 cm