Bamboo is known for its rapid growth and diverse applications, from ornamental landscaping to construction materials. Valued for its aesthetic qualities, bamboo creates tranquil and lush environments. Its unique growth habits and versatility make it a compelling choice for gardeners and landscapers.
Understanding Bamboo Varieties
Bamboo is categorized into two main types based on their underground root structures, known as rhizomes: clumping and running bamboo. These distinctions are crucial for managing their growth and spread in a garden.
Clumping Bamboo
Clumping bamboo varieties grow in a contained manner, with rhizomes expanding slowly, typically only a few inches annually, to form a dense cluster. They are suitable for smaller gardens, containers, or areas where spread is undesirable. Common clumping varieties include species from the Fargesia genus, such as Fargesia robusta and Fargesia nitida, known for their non-invasive nature and suitability for temperate climates.
Running Bamboo
Running bamboo, in contrast, has an aggressive rhizome system that spreads horizontally underground, often many feet from the parent plant. This makes running bamboo highly invasive if not properly managed. It is often used for dense privacy screens or hedges in expansive landscapes where its spread can be accommodated or controlled. Common running varieties include species from the Phyllostachys genus, such as Phyllostachys aurea (Golden Bamboo) and Phyllostachys edulis (Moso Bamboo). Due to their vigorous spread, proper containment strategies are important when planting running bamboo.
Planting and Cultivating Bamboo
Establishing and caring for bamboo involves specific considerations regarding its environment and ongoing maintenance. Attention to site selection, soil conditions, and consistent watering and fertilizing practices helps ensure healthy growth.
Site Selection and Soil Preparation
Bamboo generally thrives in locations with full sun to partial shade, depending on the variety. For optimal growth, an open area with direct sunlight is often preferred. It performs best in well-drained, fertile soils that are neutral to slightly acidic. If the existing soil is heavy clay, incorporating organic materials like compost, peat, or aged manure can improve drainage and fertility.
Planting Techniques
When planting potted bamboo, the hole should be dug to be two to three times wider than the root ball. The plant should be placed in the hole so that the top of the root mass is level with the surrounding soil. After positioning, backfill the hole with a mixture of the excavated soil and compost, gently firming it around the root ball to remove air pockets. Watering thoroughly immediately after planting helps settle the soil and promotes root establishment.
Watering and Fertilizing
Consistent moisture is important for bamboo, especially for newly planted specimens and during dry periods. Young plants require more frequent watering, typically every two to three days, to help establish their root systems. Once established, in-ground bamboo may need watering once or twice a week, depending on climate and soil, while potted bamboo often requires more frequent watering. Curling leaves indicate insufficient water, while drooping leaves suggest overwatering or poor drainage.
Bamboo benefits from regular fertilization, particularly during its active growing season in spring and summer. It responds well to high-nitrogen fertilizers, such as a 20-5-10 NPK ratio, or organic options like fish emulsion or blood meal. Fertilizers can be applied two to three times per year, with the last application no later than the end of August to allow new culms to mature before winter.
Managing Bamboo Spread
Controlling the spread of bamboo, especially running varieties, is a common concern. Effective strategies involve creating physical barriers and regular pruning of both above-ground culms and underground rhizomes.
Containment Strategies
Physical barriers are a primary method for containing running bamboo. A specialized bamboo barrier, typically made of 40 mil thick high-density polyethylene (HDPE), should be installed vertically around the planting area. Bury the barrier 22 to 30 inches deep, with 2 to 4 inches extending above the soil line to prevent rhizomes from growing over the top. Overlap ends by about four feet and seal them securely to prevent breakthrough.
Planting bamboo in sturdy containers is another effective containment method. Containers should be large enough to accommodate root growth, ideally with a diameter of 18 to 36 inches and sufficient depth. Robust materials like metal, thick plastic, or concrete are recommended, as roots can penetrate weaker materials. Ensure adequate drainage holes and place containers on pot feet to prevent waterlogging.
Creating natural barriers, such as a trench around the planting area, can also help. A trench dug to a depth of approximately 28 inches allows for monitoring and removal of emerging rhizomes. Regular inspection and removal of any rhizomes found are important to prevent escape.
Pruning for Control
Pruning culms, the bamboo stalks, can help manage the plant’s size, density, and aesthetic appearance. Thinning out older, damaged, or crowded culms improves air circulation and provides space for new growth. Cuts should be made as close to ground level as possible when removing entire culms. For height reduction, culms can be topped by cutting just above a node; these culms will not grow taller but will become bushier.
Regular pruning of underground rhizomes is an effective way to control the spread of running bamboo. This can be done by driving a sharp spade around the perimeter of the bamboo’s designated area, severing any outward-growing rhizomes. Rhizomes typically grow in the top 2 to 5 inches of loose topsoil, making them accessible for cutting. This practice should be performed bi-annually, ideally in late spring and fall, when rhizome growth is active but still relatively tender. Removing new shoots as they emerge also helps deplete the energy stored in the rhizomes, eventually reducing spread.
Common Bamboo Issues and Solutions
Even with proper care, bamboo plants can sometimes exhibit signs of stress or fall victim to pests. Recognizing these common issues and implementing timely solutions can help maintain plant health.
Yellowing leaves on bamboo can indicate several issues, including overwatering, underwatering, too much direct sunlight, or nutrient deficiencies. Soil that is consistently too wet can lead to root rot, causing leaves to yellow and droop. Conversely, insufficient water can also cause yellowing, often accompanied by brown, crispy leaf tips. If too much sunlight is the cause, moving the plant to a location with dappled or indirect light can help. Nutrient deficiencies, particularly a lack of nitrogen or iron, can also lead to yellowing; applying a balanced, high-nitrogen fertilizer or an iron supplement can address this. Removing yellowed leaves helps promote new growth.
Brown leaf tips on bamboo are frequently a sign of low humidity, underwatering, or salt buildup in the soil. In dry environments, increasing ambient humidity around the plant, such as through misting, can be beneficial. Ensuring consistent and deep watering helps prevent the soil from drying out excessively between waterings. If salt buildup is suspected, flushing the soil with plain water can help leach out excess salts.
Bamboo is generally resilient to pests, but certain insects can occasionally become problematic. Common pests include spider mites, aphids, and mealybugs. Spider mites often cause small, discolored spots on leaves and may create fine webbing. Aphids are small, pear-shaped insects that feed on plant sap, often leading to sticky honeydew residue and subsequent sooty mold. Mealybugs appear as white, cottony masses, typically in branch joints.
For minor infestations, a strong spray of water can dislodge pests. Horticultural oils or insecticidal soaps can be applied for persistent problems, following product instructions. Maintaining good air circulation also deters some pests.