Threadleaf bluestar (Amsonia hubrichtii)

Also known as: Bluestar, Hubricht's amsonia, Narrow leaf blue star

Threadleaf bluestar (Amsonia hubrichtii) is named in honor of Leslie Hubricht, a distinguished biologist who discovered the plant in the 1940s. It is widely favored in gardens for its use in borders, rock gardens, and cottage gardens. This plant pairs beautifully with fall-blooming perennials like garden mums and sedums.

In This Article

Care Tips Water Sunlight Temperature Soil Fertilize Prune Propagation Repotting Toxicity

Attributes of Threadleaf bluestar

Lifespan

Perennial, Annual

Plant Type

Herb

Plant Height

60 cm to 90 cm

Spread

60 cm to 90 cm

Leaf Color

Green Yellow Gold

Flower Size

1.3 cm

Flower Color

Blue White

Images of Threadleaf bluestar

Quickly Identify Threadleaf bluestar

Feathery green foliage forms a dense and airy mound up to 3 feet (90 cm) tall and wide.

Terminal clusters of 1/2 inch (1.3 cm) sky-blue star-shaped blooms in spring.

Elongated pods, 2-3 inches (5-7.5 cm) long, with linearly arranged seeds.

Needle-like leaves, 2-3 inches (5-7.5 cm) long, turn golden in full sun.

Green, milky-sapped stems up to 3 feet (90 cm) tall with smooth branching structure.

Scientific Classification of Threadleaf bluestar

Phylum

Vascular plants

Class

Dicotyledons

Order

Gentianales

Family

Dogbane

Genus

Bluestars

Species

Threadleaf bluestar

Planting and Growing of Threadleaf bluestar

Care Difficulty

Easy

Watering Schedule

Every 4 days

Sunlight Requirements

Full sun

Sunshine Duration

4-8 hours

Ideal Temperature

60-70℉

Soil Type

Potting Mix, Peat Mix

Soil pH

6-7

Fertilizer Type

Balanced

Pruning Season

Spring, Summer

Pruning Area

Branches, Leaves

Pruning Frequency

2 times a year

Repotting Season

Spring

Pot Type

Terracotta, Plastic

How to Water Threadleaf bluestar?

Amsonia hubrichtii prefers consistent moisture but well-drained soil. Watering should ensure that the soil is moist, but not soggy. During active growing seasons, about 500ml each time is recommended, enough to thoroughly moisten the root area.

What are the symptoms of an underwatered Threadleaf bluestar? ›

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What are the symptoms of an overwatered Threadleaf bluestar? ›

How to save an overwatered Threadleaf bluestar? ›

What Are the Sunlight Requirements for Threadleaf bluestar?

Sunlight Requirements: Full sun, Partial sun

Duration of light: 6 to 8 hours

Amsonia hubrichtii thrives in full sun to partial sun environments. Ensuring ideal lighting fosters floral development, rich leaf color, and a sturdy growth habit, promoting a visually appealing and healthy plant.

What is the best lighting condition for Amsonia hubrichtii? ›

How can I achieve ideal lighting for Amsonia hubrichtii? ›

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What Is the Ideal Temperature Range for Threadleaf bluestar?

Ideal Temperature: 60 ~ 70℉

The ideal temperature range for Amsonia hubrichtii is between 60°F and 70°F. This range ensures optimal growth and flowering, providing the plant with the right conditions to thrive while minimizing stress. Such temperatures typically support healthy photosynthesis and metabolic processes within the plant.

What Soil is Best for Threadleaf bluestar?

Soil type: Loam, Sandy loam

Soil PH: 6 ~ 7

Amsonia hubrichtii thrives in well-draining soil, preventing potential root rot by allowing excess water to escape quickly. This condition ensures the roots receive adequate aeration, promoting healthier growth. Preferring moderate fertility, this plant does not require overly rich soil. Balanced nutrients support steady growth without overwhelming the root system or prompting excessive foliage at the cost of blooms. While tolerant of drought, Amsonia hubrichtii benefits from consistent moisture, particularly during prolonged dry spells. Soil that retains moderate moisture can promote robust foliage and abundant flowering.

How to Fertilize Threadleaf bluestar?

Fertilizer type: Balanced

Amsonia hubrichtii prefers a light feeding. For liquid fertilizers, apply a solution with half the strength recommended for houseplants. For slow-release fertilizers, use around 1 pound per 100 square feet annually.

How to Prune Threadleaf bluestar?

Pruning Time: Spring, Autumn

Start by cutting back the foliage in late spring after the plant has bloomed. Trim back about one-third of the plant's height. This helps the plant maintain a tidy shape. In autumn, perform a more comprehensive pruning by cutting back all stems to about 6-10 inches from the base. This encourages a dense, mounded structure in the next growing season. After the blooming period, remove dead flowers by cutting them off at the base. This process, known as deadheading, will not only improve the plant's appearance but also redirect its energy into strengthening the roots and stems, making for a healthier plant in the future. More About Pruning Techniques→

How to Propagate Threadleaf bluestar plant?

Propagate Time: Spring, Early autumn

Harvest seeds from Amsonia hubrichtii as they mature in late summer. Sow them in seed trays filled with a well-draining seed-starting mix. Cover seeds lightly with soil, and maintain consistent moisture until germination, which may take several weeks.

Select healthy stems from the plant in the early morning. Cut 4-6 inch stem sections using clean pruners. Remove the lower leaves, dip the cut end in rooting hormone, and plant the cutting in a pot filled with moist, well-draining soil.

In the early autumn or spring, dig up the plant and gently divide the root ball into sections, ensuring each division has roots attached. Replant the sections at the same depth they were growing previously, and water them thoroughly.

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How to Repot Threadleaf bluestar plant?

Repotting frequency: Every 2-3 years

Amsonia hubrichtii signals its need for repotting when its growth stagnates or when roots start peeking out from the drainage holes. Spring or early Autumn are ideal to give the plant ample time to adjust before extreme temperatures hit.

Select a pot that is 1-2 inches larger in diameter than the current one, with sufficient drainage holes. This ensures the roots have room to grow, while avoiding excess soil that could retain too much moisture.

Opt for a well-draining potting mix that contains components like perlite, coarse sand, or fine pine bark. This prevents root rot by enabling excess water to drain away, maintaining optimal humidity and aeration around the roots.

Toxicity of Threadleaf bluestar

Is Threadleaf bluestar toxic to humans?

The threadleaf bluestar exhibits mild toxicity when its sap comes into direct contact with the skin. Concentrated primarily in the stems and leaves, it is prudent to minimize contact with these parts or to wear gloves and protective gear to shield the skin from potential irritation during handling. Additionally, certain species of the *Amsonia* genus have been identified to produce toxic alkaloids that pose risks if ingested. For these reasons, consuming this plant or using it internally is strongly discouraged.

Is Threadleaf bluestar toxic to cat?

Threadleaf bluestar possesses a degree of mild toxicity for cats. If ingested in excessive amounts, this plant could result in potential poisoning, given that its sap or juice contains toxic substances. Cats consuming a substantial quantity of threadleaf bluestar may show a range of distressing symptoms, potentially indicating physical discomfort. Cat owners need to be attentive and make sure their feline friends do not chew on or ingest any part of threadleaf bluestar. If poisoning is suspected, it is essential to seek prompt veterinary attention to safeguard the health of the affected cat.

Is Threadleaf bluestar toxic to dog?

Threadleaf bluestar presents a mild toxicity risk to dogs. Poisoning generally happens when a dog consumes a significant amount of the plant. The sap or juice of the threadleaf bluestar is the toxic component that can cause negative effects if swallowed. Dogs that suffer from poisoning due to threadleaf bluestar may show symptoms like gastrointestinal distress, vomiting, or diarrhea. It is vital for dog owners to keep an eye on their pets and prevent them from consuming excessive quantities of this plant. If a dog ingests threadleaf bluestar and exhibits signs of poisoning, it is essential to seek immediate veterinary attention to ensure appropriate treatment and symptom management.

WARNING

The judgment on toxicity and danger is for reference only. We DO NOT GUARANTEE any accuracy of such judgment. Therefore, you SHALL NOT rely on such judgment. It is IMPORTANT TO SEEK PROFESSIONAL ADVICE in advance when necessary.

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