How to Grow Tweedia

Star shaped blue flowers of tweedia caerulea planted outdoors.
naotoshinkai / Getty Images
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Finding a plant with blue flowers is rare, but finding one whose flowers are also fragrant and whose foliage is attractive is even rarer. Tweedia has all three, which makes it a popular choice for gardens, floral arrangements, container gardens, and even bridal bouquets.

Native to South America, tweedia is best planted in the early spring after all risk of frost has passed. It pairs nicely in gardens with other late-blooming plants such as lavender, sunflower, black-eyed Susan, and purple coneflower. Your tweedia plants will grow slow and steady, reaching maturity between 70 to 85 days after planting.

Botanical Name Tweedia caerulea
Common Name Tweedia, blue milkweed, star of the Argentine, southern star
Plant Type Perennial, annual
Mature Size 2–3 ft. tall, 2–3 ft. wide
Sun Exposure Full sun, partial shade
Soil Type Moist but well-drained
Soil pH Neutral to acidic
Bloom Time Summer, fall
Flower Color Light blue
Hardiness Zones 10-11 (USDA)
Native Area South America
Toxicity Toxic to humans, dogs, and cats
A close up image of blue tweedia caerulea flowers.

chuck b. / Flickr / CC​ BY 2.0

Tweedia Care

Tweedia is a tropical twining vine or subshrub native to Brazil and Uruguay. It's beloved for its delicate sky blue flowers, which can be easily damaged by strong winds or intense rain. When choosing a spot in your garden to plant tweedia, select a location that is protected from the elements to ensure your blooms maintain their gorgeous petals throughout the whole blooming season.

Tweedia is a relatively easy plant to grow and does not require any special attention and, under the right conditions, tweedia can eventually grow to be up to 3 feet tall. As a part of the milkweed family, it attracts various types of pollinators and makes a great addition to a butterfly garden. Additionally, the plant is generally pest- and disease free—the only issue you may encounter is milkweed bugs during the tail end of their season.

Light

Tweedia will grow best if planted in an area that boasts full sun, especially in climates with cooler summers. It will also grow well in partial sun in areas with particularly hot summers.

Soil

Generally, tweedia can tolerate a wide range of soil conditions, including poor quality and nutrient-poor soils (if necessary). For best results though, plant your tweedia in moist, well-drained soils. As with most plants, tweedia does not tolerate wet feet, or having its roots sitting in water, so ensuring the soil has adequate drainage is important. Adding perlite or sand to the mixture will help to increase drainage if needed. Additionally, the plant does not have any special pH requirements, and can thrive in a range of neutral to acidic blends.

Water

Tweedia plants require regular watering in order to thrive. Well-established plants are slightly more drought-tolerant than young plants, but will still do best when given a consistent soaking. If you live in an area that does not receive very much rain, you will need to supplement rainfall with additional watering to help your tweedia thrive—about an inch a week should work well in most climates.

Temperature and Humidity

Tweedia is a heat-loving plant and requires warm temperatures in order to stay evergreen year-round. In most temperate climates tweedia is grown as an annual, or overwintered indoors as a houseplant and moved outside during the summer. Whether you're planting from seed or transplanting seedlings, wait until temperatures have reach at least 50 degrees Fahrenheit and all chance of frost has passed before moving your plant outdoors.

Fertilizer

Tweedia plants should not be fertilized until they are well-established, at which point they can benefit from fertilization during the growing season to help encourage new growth. Fertilization in the spring and summer months can help to encourage more aggressive blooming in the fall and late summer. A standard all-purpose fertilizer is typically sufficient.



Symptoms of Poisoning in Pets

  • Irregular heart rate (either increased or decreased)
  • Lethargy
  • Diarrhea
  • Excessive drooling
  • Loss of appetite
  • Nausea
  • Seizures
  • Vomiting
  • Unsteady gait/weakness

Pruning Tweedia

To help keep your tweedia plant looking full and bushy, pinch the stem tips in the spring to encourage branching. In climates where tweedia can be grown outdoors throughout the winter months, regular season-end pruning will help to encourage new growth in the spring. Cut back tweedia as you would other shrubs, making sure not to prune more than a third of the branches off at a time.

Propagating Tweedia

Tweedia can be propagated by taking softwood stem cuttings. To propagate from softwood cuttings, take a stem cutting that's approximately 4 inches in length from a mature "mother" plant during early-to-late spring. Cuttings should be taken with a sharp knife or pruning shears, and you should make sure that at least one node is present on the cutting. Remove the leaves and flowers from the lower part of the cutting, leaving at least two leaves at the top of the cutting. Make a fresh cut underneath the node closest to the bottom of the cutting, then dip the cutting in a rooting hormone. Plant your cutting in a rooting medium, water it, and then place it in a location that receives bright (but not direct) sunlight. Roots should begin to grow within four to eight weeks.

How to Grow Tweedia From Seed

Tweedia can be easily grown from seeds, either by purchasing seeds directly or by harvesting seeds from an existing plant for the next growing season. Depending on your climate, tweedia seeds can be started in various different ways. When growing tweedia as an annual, seeds can be started indoors in late summer and overwintered until the next growing season, or sowed directly into the garden after the final frost. If you are growing tweedia as a perennial, seeds can be sowed directly into the garden, or they can be started indoors and then moved outdoors once they are established. Heated seed mats are recommended for germinating tweedia seeds, as they do best when heated from beneath during germination.