Perennials & Ornamental Grasses

Maintaining mountain knapweed - everything about watering, fertilizing, cutting and overwintering


The mountain knapweed is easy to care for and makes no great demands. That is why it is the ideal plant for new gardeners who are just about to discover their green thumb.

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Summer becomes colorful when the mountain knapweed (Centaurea montana) comes up with its blue, violet, white or pink blossom fireworks. The plant, also known as cornflower, is particularly impressive in group plantings. We have put together some care instructions below. But first of all we would like to introduce you to some beautiful mountain knapweed species.

What types of mountain knapweed are common?

In most natural gardens, the blue flowering mountain knapweed can be found. There is a direct relationship to the native cornflower. However, this is annual, whereas the mountain knapweed sprouts every spring as a perennial.

❍ Mountain knapweed Grandiflora:

This species blooms in the conventional shade of blue, but has strikingly large flower heads.

❍ Mountain Knapweed Jordy:

This mountain knapweed sets beautiful contrasts with its dark red flowers.

❍ Mountain knapweed Merel:

This variety is particularly attractive, appears in a rich purple red, reaches stature heights of up to half a meter and impresses with fragrant flowers.

❍ Mountain Knapweed Rosea:

As the name suggests, it is the pink flowers that make this variety unique.

How to properly care for the mountain knapweed

To water:

The mountain knapweed needs regular watering. It comes down to a balanced relationship. The soil must not dry out, but in return the plant does not tolerate waterlogging. Keep the substrate evenly moist in a sunny location. The soil can feel damp. It is important that the irrigation water can drain off easily and does not build up. When planting outdoors, the soil can be loosened by adding coarse sand or pebbles. If the mountain knapweed is in the bucket, a layer of pottery shards on the bottom of the pot helps to ensure better drainage of the irrigation water.

Mountain knapweed tolerates calcareous water. You do not therefore have to water the plants with rainwater. Stagnant tap water is also well tolerated by the mountain knapweed. It can also be used for the plants in the bucket.


If you upgrade the soil accordingly during planting, the mountain knapweed does not necessarily need additional fertilizers. You should mix the soil with organic fertilizer such as compost or horn shavings in spring and autumn. If the soil is lean and no compost is palpable, you can alternatively use long-term fertilizer for flowering plants. Flowering plant fertilizer with a high phosphorus content promotes flowering.

To cut:

Since the plant only grows to heights of around 20 to 50 centimeters, pruning is not absolutely necessary. However, there are a number of advantages to using scissors regularly for mountain knapweed. The cutting measures start in spring. Before the mountain knapweed comes out, cut it back to the ground. If you only carry out this measure in spring instead of already in autumn, this will encourage new shoots and blooming. In order to bring the plant to flower again in autumn, you should cut back the flower stems about a hand's breadth above the ground after the first flowering.

Of course, you can also use scissors to bring the mountain knapweed into your home as an attractive cut flower. Pretty summer bouquets can be created with a lady's mantle or barbels. The cornflower in combination with roses is particularly festive and classic.

The mountain knapweed sows itself very eagerly. If you don't want the flowers to grow over your head one day, you should remove the withered flowers quickly so that you don't sow them yourself.


The best time to plant mountain knapweeds is spring and autumn. If the plants are not planted too late in the autumn, the daisy family still has enough time to take root well before the first frost. Mountain knapweeds are usually hardy. You can protect the plants from severe frosts with a layer of leaves or brushwood. This way, the moisture stays in the soil longer and there is less risk of the root ball drying out.

Container plants may also overwinter outdoors. Assigning them to a location in the house could negatively affect flowering next year. Mountain knapweeds in the tub need a little more protection because the roots are more vulnerable. Cover the soil well with mulch and wrap the plant with fleece or burlap, then container plants will survive the winter without any problems.