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How to Care For Asters Flowers

Last Updated on September 17, 2022 by Plant Mom Care

The Aster is a perennial flowering genus of plants from the Asteraceae family, with around 170 species, indigenous to Eurasia, with one from North America. The name means “star” in Ancient Greek, about the flower’s shape.

This species, including several varieties of hybrids, is a very popular plant with cultivators due to the variety of colorful and attractive flowers. These plants can also thrive in a variety of climates.


Asters Light Requirements

Most of these plants prefer growing in locations under full sun for most of the day. Insufficient light causes leggy plants and less flowering, particularly for the more popular cultivars and hybrids. However, some native plants grow quite nicely in partially shaded areas.


Asters Watering

Judicious watering is necessary to give these perennials a good start. Thoroughly water them once in a week to assist new roots to grow longer. Soil should stay moist under the surface but not soggy. Watering them earlier in the day gives the leaves sufficient time to dry – try to water only the soil to avoid splashing the leaves with water to prevent attacks from mildew or fungus. 


Asters Humidity

These plants have no special humidity preferences and will not require extra humidity or extra misting.


Asters Temperature

These plants thrive under cooler temperatures between 65-70oF and are frost tolerant, capable of temporarily withstanding near-freezing conditions. Indoor care for these plants is similar, provided the plants have enough light


Asters Soil

These plants prefer growing in slightly acidic loamy soil, within a pH range of 5.8 to 6.5. If the soil is alkaline, it can be corrected with organic matter like decomposed manure, humus or compost.


Asters Repotting

When new growth starts appearing in spring, take the plants from their pots and repot with fresh soil. This will be a suitable time to also divide the plants if they have become large enough. Once they’re repotted, keep the soil always moist but not soggy.


Asters Propagation

These plants are propagated either from seeds, cuttings and division, but division is the easiest way of propagation. 

Seed propagation

Seeds can be collected from existing plants, but you could also let the plants self-seed in your garden. Their seeds are similar to those of dandelions and will help in the reproduction process.

According to studies, it will take 20-30 days for the seeds to start germinating. However, starting this process indoors in a greenhouse for example, will cut the length of the germination process by half and seeds will begin sprouting in just 15 days. However, these suggested times are only possible if the seeds are planted correctly. 

You should use a damp, sterile potting mix in seeding pots and plant two seeds in every pot at a depth of ⅛ inches. After this is done, mist the pots regularly to help establish the seeds until they germinate. Covering each pot with plastic can also help. Monitor the soil to see that the soil doesn’t become dry. 

The plastic covering can be removed once the seeds have sprouted. Reposition the pots to a place that gets sunlight all day long. After the seedlings two real leaves, remove the weaker seedlings and transplant the vigorous seedlings after winter. Nevertheless, you can continue growing the plants indoors if necessary. 


While propagating seeds is relatively straightforward, propagating cuttings or divisions offer you a distinctive advantage, if you want to reproduce exact copies of an aster variety, then these two methods will make it possible.

Using seeds doesn’t come with the guarantee that the seeded plant will be similar to the original plant as the flowers might be a result of cross-pollination or the plant is a hybrid and grows as either one of the crossed varieties. 

Using cuttings or division guarantees that you will reliably create exact copies of the plant that you’ve divided or taken the cutting from. Usually cuttings are rooted from softwood but this depends on the variety. 

Spring is a suitable time to root cuttings and the process isn’t very different from propagating other plants from cuttings. Select a healthy plant and take a 5-6 inch cutting from a healthy stem. Prepare the cutting by removing the lower leaves until all that remains are 2-4 upper leaves. 

Gardeners typically use perlite or sand or a combination of both as a growing medium and boost rooting by using a plastic bag to cover the pot. This will help in retaining moisture. The remaining maintenance involves providing moisture, providing sufficient light and transplanting the cutting after it gets rooted. 


Dig up the plant (or when removing the plant for repotting as mentioned above) and divide it with a small spade into sections to replant. It doesn’t matter when you divide the plant – the sections will survive because the roots are tough and hardy. If this is done after flowering in autumn, the plants will get well established and start flowering in late summer.

Water the new divisions thoroughly after replanting, and fertilize them with bone meal to give them the necessary phosphorus to boost root growth. 

Additional Care

These plants need moderate feeding and appreciate being fertilized with an appropriate flower fertilizer twice in a month, starting in spring and until the flowers start to open. Excessive feeding can restrict the flowering period, so stop feeding the plants in August.

Asters Common Problems

Powdery mildew disease and rust can affect the foliage of these plants. Proper plant spacing is recommended to help improve air circulation. Avoid splashing the leaves and stems when watering to avoid these problems.

These plants are somewhat pest-free, but lace bugs can often be a nuisance. These pests are very tiny gray-brown insects and are difficult to see. You’ll most likely notice the damage these pests cause to the plant rather than the actual pests.

Signs of their presence include yellowing foliage and leaves dropping in summer. Spray the plants with insecticidal soap, making sure to spray the entire plant, not forgetting under the leaves since they can hide there. Luckily, these outbreaks usually happen before the flowering season, so bees and butterflies won’t be affected by the spraying.

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