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What is a Summer Aster?

A Summer Aster, botanically known as Kalimeris incisa 'Blue Star', is a fabulous, perennial border plant that belongs to the daisy family (Asteraceae). Although the plant closely resembles traditional autumn asters in appearance and flower shape, this variety distinguishes itself with a much longer flowering period that starts early in the season. Kalimeris incisa originates from the grasslands of East Asia. 'Blue Star' forms a beautifully compact, bushy clump of finely incised, lance-shaped green foliage. From the beginning of summer until deep into the autumn, the plant becomes completely covered with hundreds of delicate, light lilac-blue daisy-like flowers with a warm yellow heart.

The benefits of a Summer Aster

Planting Kalimeris incisa 'Blue Star' offers fantastic advantages for the dynamics and long-lasting color experience in your garden. The main benefits of a Summer Aster are:

• Unbelievably long flowering period: While most border plants stop flowering after a few weeks, this variety continues to produce new flower buds non-stop for months.
• Excellent sturdiness: The stems are tough and resilient, meaning the plant—unlike many traditional asters—does not flop or sag during a heavy summer rainstorm.
• High disease resistance: Kalimeris is practically immune to powdery mildew, a fungal disease that often plagues normal autumn asters in late summer.
• Magnet for butterflies and bees: The open flowers are filled with nectar and form an essential, long-lasting buffet for beneficial insects.
• Low maintenance: The plant has minimal requirements and recovers rapidly each spring after the winter.

What to look for when buying a Summer Aster?

When buying a Summer Aster, it is important to choose plants with a healthy, compact structure and a well-developed root system that fills the nursery pot neatly. The leaves should be fresh green and free of spots. At Planten247, we select only vital, vigorous specimens that come directly from specialized growers. If you buy the plant in early spring, you will receive a compact clump that is just starting to sprout above the soil; this is the ideal time for planting. Our strong young plants are guaranteed to establish quickly after planting and will provide a rich bloom in the same season.

Summer Aster Hardiness

The Summer Aster 'Blue Star' is exceptionally hardy and highly resistant to periods of severe frost. The plant tolerates temperatures down to -20 degrees Celsius without the need for any form of winter protection. The above-ground foliage functionally dies back in late autumn, after which the plant enters a deep rest phase underground via its sturdy rhizomes. This natural mechanism ensures that the roots remain perfectly protected against freezing and sprout vigorously again in the spring.

Combining Summer Asters

Thanks to its soft lilac-blue color and neutral, bushy shape, Kalimeris incisa 'Blue Star' is a dream plant to design with in the border. Wonderful partners to combine a Summer Aster with include:

• Coneflower (Echinacea purpurea): The sturdy, purple flowers form a fabulous color contrast with the delicate lilac-blue of the aster.
• Daylily (Hemerocallis): The large, often warm yellow or orange flowers introduce a completely different shape into the border that is beautifully softened by the fine-textured effect of the Summer Aster.
• Ornamental grasses: Such as Switchgrass (Panicum) or Fountain Grass (Pennisetum), which pair beautifully with the natural look of the aster thanks to their fine texture.
• Yarrow (Achillea): Provides a nice horizontal contrast with its flat flower heads against the round flowers of the Kalimeris.

Caring for a Summer Aster

Caring for a Summer Aster is particularly easy and takes almost no time. During the growing season, you do not need to stake the plant because it has a naturally sturdy structure. While not strictly necessary, deadheading the faded flowers in summer stimulates the production of even more new buds. The most important maintenance takes place in early spring, in the month of March. At that time, cut the entire plant back to just above the ground with sharp pruning shears. A small handful of organic fertilizer after pruning is sufficient for vital growth.

Summer Aster Flowering Time

The flowering time of the Summer Aster is one of the longest among perennials. The first delicate flowers usually open in the course of the month of June. The plant then continues to bloom non-stop throughout the months of July, August, and September with a fabulous abundance of flowers. In mild autumn weather, flowering can even continue well into October, until the first serious night frost arrives.

Summer Aster in a Pot

Due to its compact, bushy, and sturdy growth habit, Kalimeris incisa 'Blue Star' is also excellently suited for keeping in a beautiful flower pot or planter on the patio or balcony. It provides months of color at eye level without the plant drooping. When planting in a pot, always ensure good water drainage; excess moisture at the bottom of the pot is harmful to the roots. Use a pot with drainage holes, add a layer of hydro-granules at the bottom, and fill the container with high-quality, well-draining universal potting soil.

Sowing Summer Aster

Sowing the Summer Aster is possible, but requires some patience. The seeds are so-called cold germinators, meaning they need a period of cold to break dormancy. You can sow the seeds directly outside in the open ground in late autumn, so the winter cold can do its work. The seeds will then germinate in the spring. Please note: when sowing a specific cultivar such as 'Blue Star', the offspring may differ slightly in color and height from the parent plant. To maintain the exact same fabulous characteristics, planting a nursery-grown pot plant from Planten247 is therefore preferred.

Planting Summer Aster

Planting the Summer Aster can, in principle, be done all year round, provided the soil is not frozen hard or there is no extreme summer drought. The absolute best planting time is spring or autumn, when the soil is naturally moist. Choose a location in full sun to light partial shade; the more direct sunlight the plant receives, the richer and more compact the flowering will be. The soil must be well-draining, moderately fertile, and normally moist. At Planten247, we recommend maintaining a planting distance of approximately 30 to 40 centimeters, which translates to 7 to 9 plants per square meter for a beautifully covering effect.

Buying Summer Aster at Planten247

Do you want to enrich your border with a reliable, ironclad, and extremely long-flowering perennial? Buying a Summer Aster at Planten247 means choosing perfectly healthy plants of absolute top quality that come fresh from the grower. We pack our perennials with the greatest expertise and care, ensuring they arrive at your home in optimal condition. With the Kalimeris incisa 'Blue Star', effortlessly add months of color, rhythm, and a fabulous natural atmosphere to your outdoor space.

Frequently Asked Questions about the Summer Aster

Is a Summer Aster poisonous?

No, the Summer Aster is completely non-toxic and safe for both humans and animals. The plant contains no toxic substances, making it perfectly safe to touch while gardening or pruning. This perennial is also completely harmless to dogs and cats. Should your pet playfully roam along the border or accidentally nibble on a green leaf, you do not need to worry about any health risks.

How tall does a Summer Aster get?

Kalimeris incisa 'Blue Star' reaches a mature height of approximately 50 to 60 centimeters. This makes it an ideal structural plant for the foreground or middle of a border. Due to this modest and compact height, it forms a beautiful, closed green carpet that completely transforms into a lilac-blue cloud of flowers in the summer.

Is a Summer Aster evergreen?

No, a Summer Aster is not evergreen. It is a deciduous perennial whose foliage completely dies back and dries out above ground in late autumn. Although the plant is bare in winter, we recommend not cutting back the dried stems until spring. The old plant debris provides natural protection for the roots and serves as a fine hiding place for beneficial insects during the cold months.

Is a Summer Aster a perennial?

Yes, the Summer Aster is a vigorous, perennial plant with a multi-year character. The plant spreads very quietly in width via its compact rhizomes without ever becoming invasive. It returns to the same spot in the border every spring, larger, fuller, and with even more flower stems, ensuring you will enjoy it for years to come.

Should I divide the Summer Aster occasionally?

To keep the plant vital and floriferous, it is recommended to divide the clump after approximately 3 to 4 years in early spring (March). Dig up the plant, divide the root ball into several pieces with a sharp spade, and replant the young, outer sections back into the ground. This immediately rejuvenates the plant and stimulates fabulous new growth and flowering.

Is the Summer Aster drought-tolerant?

Once well-established in the open ground, Kalimeris incisa 'Blue Star' can tolerate temporary drought perfectly well thanks to its strong root system. During very hot and prolonged dry summer weeks, it is wise to water the plant thoroughly at the base once or twice a week so that bud formation and flowering remain consistently high.

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