Plant Description
Rubus spectabilis Pursh var. franciscanus (Rydb.) J.T. Howell, commonly known as San Francisco raspberry or salmonberry, is a deciduous shrub belonging to the Rosaceae family. This plant is indigenous to western coastal regions of North America, including Alaska, British Columbia, Washington State, Oregon, and California, especially in the San Francisco Bay Area.
General Appearance
The plant has an upright growth habit and can reach up to 10 feet in height. Its stems are woody, prickly, and have a reddish-brown color, while its leaves are palmate, with three to five lobes, and pale green color. Its mature bark has a peeling texture with a cinnamon-brown color. San Francisco raspberry blooms in early spring, with large, bright pink flowers that have a diameter of up to 2 inches, followed by an edible fruit that ranges in color from yellow to orange-red.
Significance and Use
San Francisco raspberry is an essential plant in the ecosystem, supporting pollinators such as hummingbirds and bees. Historically, Native American tribes have used the plant as a food source, healing plant, and for ceremonial purposes. Today, it is used in landscaping as a feature plant, with its bright-colored flowers providing a pop of color to gardens, and as a natural barrier plant, due to its woody and prickly stems.
Light Requirements
Rubus spectabilis Pursh var. franciscanus grows best in partial shade. It requires some sunlight to thrive but cannot tolerate full sun exposure. In nature, this plant is often found growing under the canopy of larger trees or shrubs, where it receives filtered light. When grown indoors, this plant should be placed near a window that receives bright but indirect light.
Temperature Requirements
Rubus spectabilis Pursh var. franciscanus prefers cool to moderate temperatures. It can tolerate temperatures as low as 20°F (-6.7°C) and as high as 80°F (26.7°C), but it grows best in the range of 45°F to 75°F (7.2°C to 24°C). Because it is a native plant of California, it is adapted to withstand mild temperatures and can tolerate occasional frost. However, it does not do well in extreme heat or cold.
Soil Requirements
Rubus spectabilis Pursh var. franciscanus grows best in well-drained, moist soil. It prefers slightly acidic to neutral soil with a pH range of 5.5 to 7.0. Ideally, the soil should be rich in organic matter, with good water-retaining capacity. It can tolerate a range of soil types, from clay to sandy loam. However, it does not do well in waterlogged or dry soil. In nature, this plant is often found growing near streams or in moist areas with good drainage.
Cultivation
Rubus spectabilis Pursh var. franciscanus (Rydb.) J.T. Howell is a thorny subshrub that is native to California. It is typically grown in gardens or as part of natural landscaping. Before planting Rubus spectabilis, choose a site with well-drained, fertile soil that receives full sun or partial shade. It prefers a slightly acidic soil pH between 5.5 and 6.5.
As a subshrub, Rubus spectabilis will form dense thickets through vegetative reproduction. Therefore, it is important to choose the right location in your garden, as it may need to be pruned regularly to prevent it from becoming invasive.
Watering Needs
Rubus spectabilis requires regular watering during its first growing season in the garden. Once established, reduce watering, and allow the soil to dry out between watering sessions. This plant is somewhat drought-tolerant, but it will require some irrigation during the dry season to maintain its foliage and flowers.
Fertilization
Rubus spectabilis does not require heavy fertilization. A single application of slow-release fertilizer during spring is enough to provide sufficient nutrients for the growing season. This plant also benefits from regular mulching to maintain soil moisture and prevent the growth of weeds.
Pruning
Prune Rubus spectabilis once a year during the winter months when it is dormant. Remove any old or damaged stems, as well as any suckers emerging from the plant's base. You can also prune the shrub to the desired size and shape. Regular pruning will help maintain the plant's health and prevent it from becoming too big and invasive.
Propagation of Rubus spectabilis Pursh var. franciscanus (Rydb.) J.T. Howell
Rubus spectabilis Pursh var. franciscanus (Rydb.) J.T. Howell, commonly known as salmonberry, is a deciduous shrub that grows up to 4 meters tall. It is native to the Pacific coast of North America, from Alaska to California. The shrub produces showy, pinkish-purple flowers in the spring, followed by edible, salmon-colored fruits in the early summer.
Propagation Methods
There are several methods for propagating Rubus spectabilis, including seed, cuttings, layering, and division.
Seed Propagation
Seed propagation is the most common method for propagating Rubus spectabilis. The seeds should be collected from ripened fruits in the summer and stored in a cool, dry place. In the spring, the seeds are sown in a well-draining soil mix and covered with a thin layer of soil. The container should be kept in a warm, bright location with regular watering until germination occurs. Seedlings can then be transplanted into individual pots or directly into the ground.
Cuttings
Softwood cuttings taken in the early summer from Rubus spectabilis can be rooted in a well-draining soil mix. Cuttings should be taken from young, healthy shoots and dipped in rooting hormone before being inserted in the soil. The container should be kept in a warm, bright location with regular watering until new growth appears. Cuttings can then be transplanted into individual pots or directly into the ground.
Layering
Layering is a method of propagation where a stem is bent down towards the ground and buried, encouraging the stem to produce roots. Rubus spectabilis can be propagated through simple layering, where a low-growing shoot is buried in a shallow trench and secured in place with a wire or peg. Once the stem has developed roots, it can be dug up and transplanted into individual pots or directly into the ground.
Division
Division is a method of propagation where the root system of the plant is divided into sections and replanted. Rubus spectabilis can be divided in the early spring, while the plant is still dormant. The root system should be carefully dug up and divided into sections, making sure that each section has several shoots and a healthy root system. The sections can then be replanted into individual pots or directly into the ground.
Disease Management
Rubus spectabilis Pursh var. franciscanus (Rydb.) J.T. Howell, commonly known as Salmonberry, can be affected by several diseases. One of the most common ones is the Phytophthora root rot, caused by the soil-borne pathogen Phytophthora. The disease will affect the roots and quickly spread to the stems, leading to wilting and death of the plant. To prevent the disease, it is important to avoid overwatering and provide good drainage. Fungicides can be used preventively in areas with known infestations.
Another disease that can affect Salmonberry is the Rust disease, which affects both leaves and stems. The disease is caused by several fungi in the Puccinia genus and is easily recognized by the orange-brown pustules on the plant. It can be prevented by removing infected material and avoiding overhead watering. Fungicides can also be used preventively to manage the disease.
Pest Management
Salmonberries can also be affected by several pests. One of the most common ones is aphids, which will suck the sap from the leaves and stems, leading to stunted and deformed growth. Aphids can be managed by washing them off with a strong water stream or by using insecticidal soap or neem oil.
Caterpillars can also be a problem for Salmonberry plants, with the larvae of several species feeding on the leaves. Handpicking the caterpillars and removing them from the plant can be effective, as well as using Bacillus thuringiensis (Bt) or spinosad as a biological control.
Finally, mites can also affect Salmonberry plants, with the webbing produced by some species leading to stunted growth and reduced yield. Miticides can be used to manage the pests, but it is important to avoid using broad-spectrum insecticides that can harm beneficial insects and pollinators.
