Choosing, Planting and Caring for Asters

Choosing the right aster variety?

Most Asters are hardy and can thrive in the same spot for many years, requiring minimal maintenance. However, Asters novi-belgii prove to be slightly more delicate than others. They include many spectacular double-flowered varieties but are susceptible to powdery mildew.

The diversity of species means there are Asters for all types of terrain. Some prefer warm, well-drained spots, while others thrive in light shade. The Aster divaricatus is ideal for woodland planting—perfect for wild and shaded gardens! For rockeries, opt for Aster alpinus or Aster tongolensis.

Asters come in various forms: some grow tall, others have a bushy habit, while some spread widely along the ground. For adding height and volume to the back of borders, choose Aster tataricus ‘Jindai’ or Aster lateriflorus ‘Lady in Black’, both reaching up to 1.20m! For borders or front-of-border planting, compact varieties like Aster tongolensis ‘Wartburgstern’ or Aster dumosus ‘Jenny’ work best. Alternatively, try Aster ‘Snow Flurry’, which spreads to form a stunning carpet of tiny white flowers.

Aster dumosus ‘Jenny’ is a compact variety with vibrant pink blooms!

Though most Asters flower in autumn, there are exceptions! For spring blooms, consider Aster tongolensis or alpinus—small varieties ideal for rockeries. For summer flowers, choose Aster sibiricus, a compact mauve-flowered type.

Some varieties boast striking, vivid blooms, like Aster dumosus ‘Andenken an Alma Pötschke’, with its bright pink flowers. Others, such as Aster ‘Monte Cassino’, offer delicate blooms that lighten borders.

For something unique, discover the eye-catching purple-and-green flowers of Aster ‘Ann Leys’!

Aster ericoïdes ‘Snow Flurry’, Aster dumosus ‘Augenweide’, and Aster ‘Ann Leys’

When to plant asters?

Plant your asters preferably in autumn, although it is also possible to do so in spring.

However, if your plants come from spring cuttings and are only weakly rooted, they will struggle to survive winter. It is best to keep them in pots under shelter and replant them the following spring. The plants we offer have been grown outdoors for 9 to 15 months: they can safely be planted directly in the garden.

Where to plant asters?

Most asters thrive in full sun or partially shaded locations, as well as well-drained soils. The Aster divaricatus is the species best suited to shade, as it can grow in woodland settings. Avoid planting them in overly heavy, clay soil, or consider lightening it with gravel or compost. They prefer cool, well-drained soil.

You can also grow them in pots or planters. In this case, opt for the Aster dumosus, which is small and compact.

Successful planting

Proper planting will allow you to enjoy your asters for years to come. To achieve this:

• Rehydrate the root ball by placing it in a basin filled with water.
• Dig a hole, with a spade or a fork, about 30 cm deep and incorporate some compost or river sand to lighten your soil if it’s clay-heavy.
• Gently tease out the roots, cutting any that remain tangled at the bottom of the pot if necessary.
• Plant carefully, ensuring not to bury the base of the leaves. If your asters are in flower, trim the flowering stems with secateurs or shears to help the plants retain their vigour.
• Water generously.
• Apply a layer of mulch to keep the soil cool.

How to care for asters?

The tallest asters require staking to maintain an upright habit. We also recommend applying mulch around their base as they thrive in cool soil conditions.

Watch our video on staking Asters, where Stéphane shares his top tips:

We also suggest pinching back your asters around June, cutting stems by one-third to half their length. This encourages bushier growth and an even more abundant flowering display.

The most common disease affecting asters is powdery mildew, particularly if you grow the more susceptible Aster novi-belgii. As both a preventive and curative measure (if treated at the first signs), spray with a wettable sulphur solution at 7 to 10-day intervals.

Dividing asters

It is advisable to divide asters at least every four years. Preferably do this in late winter or early spring, when new leaves begin to emerge. Dig them up and divide them into several clumps, ensuring each has enough roots. Then simply replant them with a bit of compost. Remember to water them well to help them establish!