Origin
Grindelia squarrosa (Pursh) Dunal var. squarrosa, commonly known as curly-top gumweed or sticky gumweed, is a flowering plant that is native to North America. It is found throughout the western regions of the United States and Canada, including the Rocky Mountains, the Great Basin, and the Pacific Northwest.
Common Names
Grindelia squarrosa is commonly referred to as curly-top gumweed, sticky gumweed, curlycup gumweed, rosinweed, and gumweed.
Uses
Grindelia squarrosa has a long history of medicinal use by Indigenous peoples, who used the plant to ease respiratory problems, such as coughs and bronchitis, as well as to treat skin irritations, wounds, and insect bites. Today, gumweed is still used in herbal medicine as a natural remedy for respiratory problems and as an analgesic. It is also used as an expectorant, diuretic, and sedative by herbal practitioners.
In addition to its medicinal uses, Grindelia squarrosa has been used as a natural dye, yielding a yellow or green hue.
General Appearance
Grindelia squarrosa is a perennial plant that can grow up to three feet tall. It has hairy stems and leaves, which are alternate, oblong, and toothed. The flowers bloom from July to September and are yellow and daisy-like, with curled-back petals. The plant produces a sticky resin that covers its leaves, stems, and flowers, which provides protection against herbivores and deters insects.
Light Requirements
The Grindelia squarrosa var. squarrosa plant requires full sun exposure to grow and thrive. It can also tolerate partial shade, but full sun is preferable.
Temperature Requirements
This plant is native to arid and semi-arid regions of North America and can tolerate a range of temperatures. However, it thrives in warm, dry conditions. It can tolerate temperatures as low as -20°C and as high as 38°C.
Soil Requirements
The Grindelia squarrosa var. squarrosa plant prefers well-draining soils that are sandy or gravelly. It can also grow in loamy or rocky soils, as long as they are not waterlogged. The soil pH range for this plant is between 5.5 and 7.5.
Cultivation methods
Grindelia squarrosa (Pursh) Dunal var. squarrosa is a beautiful perennial that can be cultivated in a sunny location with well-draining soil. You can grow it from seeds or buy nursery plants. It is essential to prepare the soil thoroughly before planting by adding organic matter and ensuring adequate drainage.
Grindelia squarrosa prefers full sun to partial shade and does well in USDA zones 3-10. It thrives in dry and arid conditions and can withstand extreme temperatures. Once established, it needs minimum care.
Watering needs
Although Grindelia squarrosa can tolerate drought-like conditions, it thrives in well-drained soil with regular watering. Water once a week during the growing season and reduce watering during the winters. Avoid overwatering as it can damage the roots and promote fungal or bacterial growth.
Fertilization
Grindelia squarrosa does not require much fertilization, but applying a slow-release fertilizer rich in nitrogen, potassium, and phosphorus during the growing season can enhance its growth and blooming. Avoid using high-nitrogen fertilizers as it can promote leaf growth rather than flowers.
Pruning
Pruning Grindelia squarrosa occurs during late fall or early spring. Prune back the stems to 4-6 inches above the ground level to encourage a compact and bushy growth habit. It also helps to remove dead or diseased foliage and improve air circulation. You can also pinch back the tips of plants in mid-summer or early fall to prolong blooming and create a fuller plant.
Propagation of Grindelia squarrosa (Pursh) Dunal var. squarrosa
Grindelia squarrosa (Pursh) Dunal var. squarrosa can be propagated through both seeds and cuttings. Here is how each method is done:
Propagation through Seeds
The first step in propagating Grindelia squarrosa (Pursh) Dunal var. squarrosa through seeds is the collection. Grindelia squarrosa (Pursh) Dunal var. squarrosa seeds are ready for harvest when the seed heads turn brown and dry. They can be collected by simply cutting the seed heads off with pruning shears or scissors and storing them in paper bags until ready to use.
Once collected, the seed heads should be broken apart to release their seeds. This can be done by rubbing the seed heads between your hands or by shaking them in the paper bag. Once the seeds are separated, they can be sown directly into the soil.
To sow the seeds, choose a well-draining area with plenty of sunlight. Sow the seeds in rows, with each seed spaced about 1 inch apart. Cover the seeds with a thin layer of soil and water well.
With enough water and sunlight, the seeds should germinate within 2-3 weeks.
Propagation through Cuttings
Propagating Grindelia squarrosa (Pursh) Dunal var. squarrosa through cuttings is a bit more complicated than propagating through seeds, but it is still a viable option.
The best time to take cuttings is in the spring, when the plant is just starting to grow. Cuttings should be taken from the tips of the plant, with each cutting about 6 inches long.
Once the cuttings have been collected, they should be dipped in rooting hormone to promote root growth. Then, they can be planted in a well-draining soil mixture.
After planting, the cuttings should be watered well and placed in a warm, humid environment with plenty of light. This can be achieved by covering the cuttings with a clear plastic bag and placing them in a sunny area of the house.
With proper care, the cuttings should start to root within 2-3 weeks.
Disease Management
Grindelia squarrosa (Pursh) Dunal var. squarrosa is generally a hardy plant, but it can still suffer from certain diseases. Here are some common diseases that might affect the plant:
- Leaf spot: Caused by various fungi, it affects the leaves and causes brown or black spots. To manage, remove and destroy the infected leaves and promote good air circulation.
- Root rot: Caused by waterlogging, it affects the roots and causes yellowing and wilting of leaves. To manage, ensure proper drainage and avoid overwatering.
- Mildew: Caused by fungi, it affects the leaves and causes a white powdery coating. To manage, spray with fungicides and promote good air circulation.
Pest Management
Grindelia squarrosa (Pursh) Dunal var. squarrosa can also suffer from pest attacks. Here are some common pests that might affect the plant:
- Aphids: Small, pear-shaped insects that suck the sap from the leaves. To manage, spray with insecticidal soap or neem oil.
- Spider mites: Tiny, spider-like creatures that feed on the underside of leaves. To manage, spray with insecticidal soap or neem oil and increase the humidity in the area.
- Caterpillars: Larvae of various moths and butterflies that feed on the leaves. To manage, handpick the caterpillars or spray with Bt (Bacillus thuringiensis) insecticide.
