Amsonia Plants General Care Guide

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The Amsonia genus refers to the herbaceous perennial plants native to North America. They’re commonly known as blue star plants because of their star-shaped blue flowers.

About 20 blue star species belong to the Amsonia genus. Because they’re sturdy plants, they’re known to symbolize endurance, strength, and determination.

Let’s learn more information about the plant Amsonia.

More About Amsonia Plants

Amsonia species are popular in many types of gardens, including butterfly and pollinator gardens, because they attract hummingbird moths, carpenter bees, and butterflies. They’re low-maintenance plants, deer-resistant and drought-tolerant once established.

The common name blue star describes the beautiful light blue flowers obvious from early summer to late spring. Blue star plants outdoors grow erect and have a clumping growth habit. Some species may grow up to 4 feet tall, while others are shorter, reaching only 4 inches in height.

Blue star plants are also called eastern blue star or blue dogbane. They’re known to be deciduous, and their leaf color change to interesting yellow fall foliage.

The Eastern Blue Star is a perennial wildflower endemic to the sandhills and coastal plains of North Carolina. This upright plant reaches 1-3 feet tall and bears light blue flowers with yellow centers that bloom from spring through fall. The flower’s five petals stand out against the slender green leaves.

Bluestar Care Tips

Amsonia plant care requires very little maintenance. Hence, it’s quite easy to tend to this plant indoors, even if you’re new to gardening. Below is a simple guide on how to grow Amsonia plants.

Soil

amsonia potting soil

This plant is found in wet, sandy, rocky woods and thickets in the wild. Hence, you need to achieve this type of media for growing Amsonia plants. It should be rich and moist soil but well-draining. Adjust the pH to be between 6.0 to 7.0.

Incorporating the soil with well-rotted manure helps improve the soil’s fertility. On top, spread over a thick layer of organic mulch like pine straw.

Light

Amsonia plants grow best under full sun. So for best results, plant it in a location where light is in full access, about six or more hours of direct sunlight. Partial shade is also tolerable, but too much shade is not good because it will cause the blue star plant to slump.

amsonia plant under full sun

The availability of full sun helps produce vigorous plants and more flowers for your blue star plants.

Water

Blue Star has average watering needs. Never let the soil go totally dry before watering again. Make sure to do deep watering to make the soil moist and help the plants develop extensive root systems. Also, ensure that the soil drains well so it won’t get soggy.

Once established, blue star plants can be drought tolerant.

Fertilizer

water soluble fertilizer

Provide water-soluble fertilizer once the blue flowers have faded. Dilute it to half-strength using water. Use fertilizers that release nutrients slowly, so the plant is not forced to spurt. During early Spring, use high-nitrogen feeding to induce new growth of foliage.

But once the flower buds emerge, use a high-phosphorus feed to boost its flowering.

Humidity and Temperature

amsonia temperature and humidity

A hot and humid climate is best for the growth of Amsonia plants. They grow in a wide range of climates, including USDA zones 3 to 9. So if you live under these zones, you can grow blue star plants without trouble.

Propagation

There are various ways to propagate your blue star. If you have an existing parent plant, you can reproduce easily using stem cuttings, root cuttings, or through division. These cuttings will give rise to new shoots once planted in a growing medium.

Once new leaves emerge, that indicates that the propagation is successful.

Another method is to start seeds. However, this process takes a longer time to grow. But if you want to do mass planting, seeds are a more fitted option.

Pruning

Part of the pruning practices is trimming back the whole plant to about 1/3 of its size. This is to prevent them from getting floppy and eliminate seed pods that may spread seeds unnecessarily. Cutting back also helps promote fuller growth in the next growing season.

The long stems of blue star plants produce a milky sap when cut. Make sure to use gloves when pruning to avoid skin irritation.

Blue Star Flowers

blue star flower @flickr

The blue star flowers are the main attraction of Amsonia plants. Each flower is tiny, less than an inch in size. It has 4 to 5 petals resembling the shape of a star. When these blue star-shaped flowers hang in fluffy clusters, they create a very showy look during the flowering season in Spring until Summer.

Aside from pale blue flowers, some varieties of Amsonia plants also produce pink, white, and purple flowers.

Amsonia Similar Plants and Varieties

Amsonia illustris

Amsonia illustris

Commonly known as the Ozark blue star, Amsonia illustris is a species of Amsonia plants that are mostly found in the Ozark region of the state (Steyermark). The word “illustris” means lustrous or brilliant, perfectly describing its shiny foliage.

Amsonia hubrichtii

Amsonia hubrichtii

This species is also known as the thread lead blue star or Hubricht’s blue star. Its foliage is feathery, soft-textured, and needle-like. They turn golden yellow during fall, making the entire plant look attractive.

Check our Amsonia hubrichtii plant care for a complete growing guide.

Amsonia tabernaemontana

Amsonia tabernaemontana

Amsonia tabernaemontana has soft blue flowers and stems that may grow up to 3 feet tall. Its foliage is dull green and turns into a yellow fall color. This species is known as the common blue star.

Bluestar Diseases and Pests

Luckily, the blue star is not a regular favorite of common pests we see in most ornamental plants.

But in terms of disease, the blue star is susceptible to mycosphaerella leaf spot and plant rust. Make sure to provide good ventilation to prevent the pathogens from growing.

Frequently Asked Questions

Lift the entire root ball and cut it into sections depending on its size. Separate the sections, including the stems above.

Yes. It would be best to cut it back to 2/3 of its size after the flowers have faded. Cutting back helps the plant grow denser.

It’s not necessary to deadhead Amsonia plants, but you can cut them back.

No. Amsonia plants are not invasive.

It will take about 2 to 3 years for Amsonia blue star to grow and mature.

You can visit your local garden centers or you can get one here at Plantly.

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