Aster flowers are beautiful, daisy-like blooms. They are favorites in gardens because they add vibrant color, especially in the late summer and fall when many other flowers have finished blooming.
Asters grow well with companion plants like coneflowers, goldenrods, and ornamental grasses, which can help create a stunning and diverse garden. Their bright, cheerful appearance and ability to thrive with other plants make asters a wonderful addition to any garden.
| Botanical Name | Symphyotrichum spp. |
| Height | 1-6 feet tall |
| Spread | 1-4 feet wide |
| Sun Exposure | Full |
| Soil Requirement | Loamy, well-drained |
| USDA Growing Zone | 3-8 |
| When To Plant | Early spring (March to early May) |
Aster originated from the tears shed by the Greek goddess Astraea. According to the story, Astraea wept upon observing the earth devoid of stars. It's said that wherever her tears landed, Aster bloomed from the soil.
The term "aster" is derived from the Greek word for "star," reflecting the flower's star-shaped appearance. Its vibrant petals extend outward from a central disc, resembling the celestial bodies above.
Growing asters is a fun and rewarding experience because they are quite easy to grow. There are several ways to grow asters, including from seeds, cuttings, and dividing existing plants. Growing asters from seeds is common because it is easy and allows you to start many plants at once.
Asters have the potential to self-seed if allowed to do so, meaning they can drop seeds and produce new plants without human intervention. However, not all aster varieties self-seed readily, so to collect the seeds, let the flowers dry on the plant until the seed heads turn brown and start to split.
Remove seed heads, dry them in a bag or container, then crush them to release seeds. Separate seeds from debris and store in a cool, dry place until ready to plant. The seeds will produce beautiful flowers that are true to the parent variety.
Here is a detailed guide on how to grow asters from seed:
Asters are typically grown from seeds during the springtime, either indoors or outdoors, depending on your location and climate. The best time to start aster seeds indoors is about 6–8 weeks before the last expected frost in your area.
For outdoor sowing, wait until after the last frost has passed and the soil has warmed up in late spring or early summer. This timing allows the seeds to germinate and the seedlings to establish themselves before the growing season peaks.
Asters are versatile plants that can thrive in various climate zones, typically ranging from USDA hardiness zones 3 to 8, though some varieties can also tolerate warmer climates. They prefer locations with full sun to partial shade and well-drained soil.
Asters are commonly grown in garden beds, borders, and containers. While they are well-suited to their preferred zones, with proper care and attention, asters can also survive and flourish in zones outside their typical range.
Whether you choose to start aster seeds indoors or sow them directly in the garden, the basic steps for growing them remain similar:
Besides growing asters from seeds, they can also be propagated through division and stem cuttings. Both division and stem cutting are fruitful methods for propagating aster plants, allowing you to create new plants from existing ones. The division is best done when the plant is dormant or just starting to grow, while stem cuttings are taken during the growing season.
This method involves splitting an existing aster plant into smaller sections, each with its own roots and shoots. It's best done in early spring or fall when the plant is dormant or just beginning to grow.
To divide an aster plant,
The stem-cutting method of propagation involves taking a piece of a plant's stem and encouraging it to grow roots, ultimately creating a new plant. Here's how it works:
After growing aster plants, caring for them is the next important step to ensuring they thrive and produce beautiful blooms. Caring for asters is generally easy, but it requires attention to specific requirements:
Asters thrive in sunlight, needing at least 6 hours of direct sunlight each day. Adequate sunlight promotes robust growth and abundant flowering. If growing them indoors, place them near a south-facing window to ensure they receive sufficient light.
In areas with scorching afternoon sun, partial shade during the hottest part of the day can protect the plants from heat stress.
Asters prefer loamy soil with good fertility. Amending the soil with compost or organic matter enhances soil structure and provides essential nutrients for healthy growth.
Mulching around the plants helps retain moisture, suppress weeds, and regulate soil temperature.
Consistent moisture is vital for asters, especially during the growing season. Water the plants deeply, ensuring the soil is evenly moist but not waterlogged. Avoid overhead watering, as wet foliage can promote fungal diseases.
Water early in the day to allow foliage to dry before evening, reducing the risk of disease. During hot and dry periods, increase watering frequency to prevent drought stress.
Asters prefer moderate temperatures, thriving in daytime temperatures between 60-75°F (15-24°C) and cooler nights. Protect them from extreme heat, which can cause wilting and flower drops.
In colder regions, provide winter protection by mulching around the base of the plants to insulate the roots from freezing temperatures.
While asters tolerate a range of humidity levels, they perform best in moderate humidity. Good air circulation around the plants helps prevent fungal diseases, such as powdery mildew. To improve air circulation, space plants adequately when planting and avoid overcrowding.
For asters, it's important to use a balanced fertilizer in early spring, when they start growing again after winter. A general guideline is to apply fertilizer at a rate of 1/4 to 1/2 pounds per 100 square feet of garden bed or container.
Apply fertilizer evenly around the base of the aster plants, keeping it away from the stems to prevent burning. Lightly scratch the fertilizer into the soil surface, then water thoroughly to help the nutrients penetrate the root zone.
Asters can be moderately affected by cold temperatures, especially if exposed to frost or freezing conditions. Prolonged exposure to freezing temperatures can damage their foliage and roots, leading to wilted or discolored leaves, reduced flowering, and even plant death in severe cases.
To protect asters from cold damage, apply a layer of mulch around the base of the plants in late fall to insulate the roots and regulate soil temperature. Additionally, cover the plants with a frost cloth or row cover when frost is expected to protect them from freezing temperatures overnight.
When growing asters in containers, choose pots with drainage holes to ensure proper drainage. Use a well-draining potting mix and repot the plants into larger containers as they outgrow their current pots.
Repotting encourages healthy root growth and prevents the plants from becoming root-bound, which can restrict growth and flowering.
Pruning is a beneficial step in caring for asters. Asters can grow quite tall and bushy, reaching heights of 1 to 4 feet and spreading up to 2 to 3 feet wide, depending on the variety. When asters become overgrown or leggy, pruning helps maintain their shape, encourages bushier growth, and promotes better air circulation, which reduces the risk of disease.
The best time to prune asters is in early to mid-spring, just as new growth begins to emerge. You'll need a pair of clean, sharp pruning shears or scissors for the job. Here are the simple steps to prune asters:
There are approximately 250 types of aster flowers, with many species and cultivars available for gardening. These can be broadly categorized into two main types: New England asters and New York asters.
New England asters tend to be very tall, growing up to six feet in height. They have thick and hairy stems, and their leaves are also hairy. They prefer full sun and bloom in late summer and early fall, bringing color to a garden that is beginning to fade.
These types are particularly notable for their medicinal and ethnobotanical uses, with the roots and leaves used by various Native American tribes for treating fevers and other ailments.
Some popular New England asters are:
New York asters are somewhat smaller, but can still reach three to five feet in height. They have smooth and thinner stems, and their leaves are smooth. They also prefer full sun and bloom in late summer and early to mid-fall.
Popular examples of New York asters are:
Aster plants can be susceptible to pests and diseases, mainly due to their lush foliage and attractive flowers, which can attract unwanted visitors. Some common pests and diseases that may affect asters include:
To keep your aster plants healthy and resilient against pests and diseases, maintain good garden hygiene by removing dead plant debris, providing adequate spacing between plants, and avoiding overhead watering.
By practicing proactive management techniques and promptly addressing issues as they arise, you can help ensure the health and vigor of your aster plants.
