Aster: planting cultivation maintenance flowering

The botanical genus Aster includes multiple species of perennial plant which, for the vast majority of them, bloom in autumn. Some asters are classified in the genus Symphyotrichum. All of them, however, belong to the family of Asteraceae (like the Marguerite!). They are very popular with gardeners for their floridity, their wide range of colors and their ease of cultivation. Those are hardy plants that we can have the pleasure of admiring in all our regions. Let’s find out how to plant them, what conditions are best for them, what their maintenance needs are, and also take the time to look at flowering asters.

Plant the asters

It is advisable to prepare the soil before planting. This involves a good deep diggingnamely about 40 cm, followed by a organic manure amendment. Rich and loosened, the soil can then accommodate different varieties. The planting asters in the ground proceeds as follows.

  • Immerse the pots containing the plants in a container of water,
  • Leave them there for at least fifteen minutes, i.e. until the clods are saturated,
  • Dig planting holes about twice as large as the clods,
  • Unpot the plants, taking care not to damage them,
  • Slightly part the roots so that they are not too tight,
  • Position an Aster foot in each hole,
  • Reseal,
  • Tamp down so that when watering, the clods do not rise,
  • Water copiously.

It is very useful to install stakes at the foot of the tall asters, especially if they are exposed to strong winds. About the distance de plantation between asters, it depends on the species. We respect intervals of 25 cm between dwarf asters, but the space between two asters that can reach 1 meter in height must be 55 cm.

If one wishes plant an aster in pot, a soil for flowering plants such as geraniums for example is quite suitable. It is of course necessary to choose a container with a pierced bottom and to deposit before the substrate a good layer of drainage (gravel, balls of clay, shards of terracotta…).

Growing and caring for asters

This is in autumn what is the best time to plant Aster? But don’t worry gardeners who missed the boat, they can plant in the spring.

The Aster likes to be installed under the sunbut tolerates semi-shaded exposure. Regarding its culture medium, it can be a good garden soil loose, sufficiently rich and which, preferably, keeps the freshness while being however well drained.

Ideal plant for the beginner gardener, l’Aster n’a no great demands in terms of maintenance.


Once it is planted in the ground, the Aster only requires watering in the event of drought or scorching temperatures for several days. If it is in a pot, it must be watered as soon as the substrate begins to dry out.


The right solution for save water and despite everything retain soil moisture consists in installing at the foot of the asters a mulch of hemp, Fragmented Raméal Wood (BRF), flax flakes or quite simply dead leaves previously crushed.


Asters are vigorous plants. Care is therefore taken to ensure that their substrate does not become depleted. In pots or planters, they need a supply of fertilizer for flowering plants every two weeks. We opt for a fertilizer to dilute in irrigation water.

As for the fertilization needs of asters grown in the ground, they are generally met by the amendment carried out just before planting. Then just make a contribution of mature compost every spring.


In the month of Junewe can pinch the end of the stems of the great varieties fall-flowering asters. This leads to branching of the stems, consequently even more abundant flowering, and reduces the risk of breakage in the event of strong winds.

Divide the stumps

Within 3 or 4 years, you can end up with large clumps of asters. It is therefore necessary to divide the strains in autumn or possibly at the beginning of spring in order to ventilate. This limits the risk of disease and allows the plants to maintain their beautiful vigour. New shoots can be replanted elsewhere in loosened and enriched soil.

Pests and diseases

Very insect pest resistantasters are on the other hand quite sensitive to certain maladies cryptogamiques (or fungal diseases) as’powdery mildew and the mildew whose responsible are pathogenic fungi. These diseases are favored by excessive hygrometry associated with temperatures of the order of 12 to 25°C.

As a preventive measure, of course, avoid overwatering your asters. They can also be protected with a sulfur preparation but only at the end of August. If they are already affected by powdery mildew, it is possible to spray them with a garlic decoction.

To control downy mildew, it is advisable to spray the tops and undersides of aster leaves with a homemade preparation made up of a tablespoon of bicarbonate de sodium per liter of non-calcareous water. Of course, we only intervene in dry weather.

But in either case, before applying a curative treatment, it is essential to remove all diseased parts and of burn them. Under no circumstances should they be incorporated into the compost as this would only risk contaminating other plants during the next amendment.

Flowering of the Aster

An Aster is a hardy ornamental perennial that tolerates down to -15°C without flinching. This plant blooms profusely throughout the fall, for most species anyway. Some bloom in the spring, for example Aster togolensis et Alpine asterand others in the height of summer, which is the case of the variety Aster amellus. It is therefore very wise to opt for an association of aster varieties in order to enjoy generous flowering for nearly 10 months a year.

Aster inflorescences are flower headsvery characteristic of the family of Asteraceae. What is commonly thought to be the Aster flower is more accurately a group of small florets. The brown, yellow or orange heart is surrounded by false colored petals called ligules. In full bloom theeffect is magical. Asters bring to the garden a note of extraordinary gaiety because of the wide variety of colors in which they occur.

The asters, which symbolize confident love in the language of flowers, work wonders in a flowerbed, a flower bed, a rockery, at the foot of trees, and find their place just as much as a window box as in a flowerpot on the terrace, the edge of a window, the balcony.. Do not hesitate to plant them everywhere because in addition to enchanting us, their very melliferous flowers attract a large number of pollinating insects such as butterflies and bees. And the more varieties we grow, the more we can create sumptuous bouquets of fresh flowersbecause those of the Aster hold particularly well in a vase.

To promote the appearance of new shoots which will bloom in turn, take the time to cut off the faded flower heads as you go. This also makes it possible to preserve the very neat look of the colorful beds. If the plants are not affected by a fungal disease, the plant debris can be incorporated into the compost or used as an organic mulch.

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