Bamboo is a versatile and rapidly growing plant, often chosen for its aesthetic appeal and practical uses. It is suitable for privacy screens, ornamental features, or erosion control, offering distinct texture and visual interest. Understanding its specific growth habits is important for successful cultivation and management.
Understanding Bamboo Types
Bamboo varieties are categorized into two main types based on their underground root systems, known as rhizomes: clumping bamboo and running bamboo. These distinctions determine the plant’s spread and suitability for different garden settings.
Clumping bamboo forms a compact, non-invasive growth habit, with rhizomes growing in a tight, U-shaped clump that expands slowly and predictably. This type is ideal for smaller gardens, containers, or areas where natural containment is desired. Examples include Fargesia species and Bambusa multiplex ‘Alphonse Karr’. Clumping bamboos generally do not require physical barriers to control their spread, making them a lower-maintenance option.
Running bamboo is characterized by its aggressive, spreading nature due to long, independent underground rhizomes that can extend several meters annually. These rhizomes can emerge far from the original planting site. Popular running species include those in the Phyllostachys genus, such as golden bamboo (Phyllostachys aurea) or black bamboo (Phyllostachys nigra). Due to their vigorous spread, running bamboos require proactive containment measures to prevent them from becoming invasive. Choosing the appropriate bamboo type depends on garden size, climate, and desired maintenance level.
Planting and Establishing Bamboo
Selecting the right site is the first step in establishing bamboo. Most species prefer full sun to partial shade, though light requirements vary. Choose a site protected from strong winds, which can damage foliage, and consider its proximity to structures or other plants for future growth.
Bamboo thrives in well-draining soil rich in organic matter, with a neutral to slightly acidic pH (5.5-6.5). Before planting, incorporate well-rotted compost or manure to improve moisture retention and nutrient availability. For heavy clay soils, add sand and organic materials to enhance drainage; sandy soils benefit from organic amendments to improve water retention.
When planting, dig a hole at least twice the width of the rootball and deep enough so the top sits level with or slightly below the surrounding soil surface. Place the plant in the hole, backfill with amended soil, and gently firm it to remove air pockets. Water thoroughly to settle the soil.
Bamboo can also be grown in containers, requiring large pots with good drainage.
Ongoing Care for Healthy Bamboo Growth
Consistent moisture is important for healthy bamboo growth, especially for newly planted specimens and during dry periods. Newly planted bamboo may need watering two to four times per week, while established plants typically require watering once or twice weekly, depending on climate and soil type. Signs of under-watering include curling leaves; drooping leaves can indicate over-watering or poor drainage.
Bamboo benefits from regular fertilization, particularly with high-nitrogen fertilizers, as nitrogen is crucial for rapid growth and vibrant green color. Fertilize in early spring before new shoots emerge and again in early summer, or use a slow-release formula. Organic options like compost, well-rotted manure, or bone meal provide a balanced nutrient supply.
Mulching heavily in the fall can protect roots in colder climates, especially for container-grown plants. A layer of mulch around the base helps retain soil moisture, suppress weeds, and regulate soil temperature.
Managing Bamboo Growth
Managing bamboo growth is important for running varieties to prevent unwanted spread. The most effective containment method is installing a physical rhizome barrier made of high-density polyethylene (HDPE). This barrier should be at least 60 cm (24 inches) deep, with 5-7.5 cm (2-3 inches) protruding above ground to prevent rhizomes from growing over it. The barrier should completely encircle the planting area, with overlapped seams secured to ensure no gaps.
Root pruning is another method to manage running bamboo, involving cutting any rhizomes that attempt to spread beyond the desired area. This can be done annually by digging around the perimeter. Growing running bamboo in raised beds or large, sturdy containers can also restrict its spread, though containers require more frequent watering and eventual division.
Pruning bamboo serves several purposes, including thinning, height control, and aesthetic maintenance.
Thinning
Thinning involves removing old, dead, damaged, or weak culms at ground level to improve air circulation and encourage new growth. This is typically done after the shooting season, often in late winter or early spring.
Height Control
Height control is achieved by cutting culms just above a node to the desired height, which encourages new foliage on lower branches.
Branch Pruning
Branch pruning, or removing lower branches, creates a cleaner appearance and exposes the culms.
Division
Division, primarily for clumping types, helps manage clump size and can be used for propagation. This process involves using a sharp spade or saw to cut a section of the rootball, ideally in late winter or early spring before new shoots emerge.
Common Bamboo Issues and Solutions
Yellowing leaves on bamboo can indicate over or under-watering, or nutrient deficiencies. Ensuring consistent, but not excessive, moisture and checking soil drainage can resolve water-related yellowing. Nutrient deficiencies, particularly nitrogen, can also cause yellowing, corrected with appropriate fertilization.
Bamboo is generally resilient to pests, but common culprits include bamboo mites, aphids, and mealybugs. These sap-sucking insects can cause leaf discoloration and stunted growth. Organic control methods include spraying affected plants with insecticidal soap or neem oil, or a strong blast of water to dislodge pests. Introducing beneficial insects like ladybugs can also help manage aphid populations.
While bamboo is largely disease-resistant, fungal spots or rot can occur, often due to poor air circulation or waterlogging. Maintaining good air flow by thinning overcrowded culms and ensuring proper drainage can prevent many fungal problems.
Lack of growth or stunted growth can stem from insufficient light, poor soil conditions, or inadequate nutrients. Ensuring the plant receives appropriate sunlight, has well-draining, fertile soil, and is regularly fertilized promotes vigorous growth. Cold damage can manifest as leaf burn or dieback of culms. While severely damaged culms may not recover, the plant often produces new shoots from the rhizomes when warmer weather returns. Mulching provides insulation, helping to protect rhizomes from extreme cold.