Care of Bamboo

Basic Terms

Culm is the above-ground stem, often called the "cane". It has nodes and is usually hollow between the nodes.

Node is the membrane spanning the inside walls of rhizomes and culms where branches, buds or roots are found.

Internode is the section of culm between the nodes. It is usually hollow.

Shooting is the rapid growth of the new culm. The height it reaches that season is the height for the life of that culm. An individual culm lives from 5 to 10 years.

Mature size is stated as a maximum height and maximum culm diameter as reported by the American Bamboo Society. The growth of bamboo is site specific. The more ideal the growing conditions the more likely it is to attain the maximums. Timber bamboos and mid-size bamboos may reach their mature height and diameter in 10 to 15 years. Shrub and dwarf bamboos may take only 3 to 5 years to reach their maximums.

Rhizome is the woody, cane-like jointed root. The amount of spread is dependent upon the species, time in the ground and the growing conditions of sun, soil and water. Hair roots form on the rhizome to take in water and nutrients. Two common types of rhizomes are:

Running bamboos (leptomorph) produce rhizomes that grow laterally through the upper surface of the soil and sometimes right above the surface. In the Pacific Northwest these primarily grow from early summer until mid fall. New culms shoot up in spring to early summer from buds spaced along the rhizome.

Clumping bamboos (pachymorph) slowly spread wider each year and do not run. Some have rhizome that are more elongated than others. Culms on cold-hardy clumpers often shoot in late spring to mid-summer and again in the fall. They grow off the tip end of the rhizome.

Planting

The temperate bamboos we sell are all quite frost hardy and suitable for USDA zones 6-9. A few are suitable for the cold of zones 4 and 5.

In the Pacific Northwest where our climate is mild, you may plant bamboo any time of year except during severe freezing temperatures. If your location receives cold winter winds then it is best to plant in the spring, or to provide protection until the bamboo has had time to acclimate.

If you decide to use a rhizome barrier, it is easier to place it before installing the bamboo. However, it can be put in years later. See "Control of Bamboo".
 

Soil Preparation All types of bamboo tolerate most types of soil, but they prefer a loamy, slightly acidic soil with a pH between 5.5 and 6.5. If you have a heavy and poor draining, clay soil, then mix compost into the top foot until the soil easily crumbles in your hand. For sandy soil, mix in compost to retain moisture and provide nutrients. Improve the entire planting area, not just the hole. Then dig a hole as deep as the root ball and twice as wide. Space root balls 3 to 5 feet apart if you want to create a hedge.

 

Plant Preparation Remove the bamboo from its container and gently loosen the soil and rhizomes around the outside of the root ball. (If bamboo is in a burlap-wrapped ball, cut off the top tie and make a few cuts in the burlap from top to bottom. Do not pull it off if you see new hair roots forming. The burlap will decompose.) Though it may appear root-bound it is better not to cut or separate the rhizomes unless it is severely root-bound or you wish to propagate small starter plants. Set the bamboo in the hole so the base of the culm is close to ground level.

 

Back Filling and Watering Replace soil until the bamboo is half planted. Then flood the pit with water and wait until it drains away. This washes soil into air pockets. Then complete the back filling. Create a reservoir (mounded ring of soil) and tamp down the soil inside. This will trap and hold water for your new planting.

 

Staking Tall or top-heavy bamboo needs staking for the first couple of years so it will not rock in the wind. This would disturb the newly forming root system. Place 3 small stakes, evenly spaced around the outside of the root ball. Tie nylon stockings or non-abrasive ropes from a stake to about halfway up a culm.

Watering
 

Newly Planted Bamboo Keep the soil moist, not soggy, for the first two weeks. Too much water will cause excess leaf drop. During the shorter daylight and rainy seasons the bamboo uses less water. Rainfall may not reach the bottom of the root ball so be sure to check for moisture below the top inches of the soil.

 

For the First and Second Year Water deeply at least once or twice a week during warm-dry/light rain or cold-dry weather. Make sure the water is going into the roots, not just running off. Soaker hoses (or drip irrigation) grow healthier plants with less water. Very dry soil can repel water, so check carefully for depth of moisture. Water regularly as new culm shoots appear.

 

Later Years Occasional deep watering during summer or fall dry spells should be sufficient in the Pacific Northwest. If you notice leaves curling up, it is a sign of stress. Dryness is often the cause. Wise Watering Tip: Irrigate for 15 minutes, then turn water off. Check several hours later to see if water has infiltrated the bamboo's root zone (top 8-12 inches). If necessary, irrigate and check again.

Fertilizing
 

Newly Planted Bamboo A root stimulator is recommended weekly for the first month to help establish the plant and reduce root shock. A slow release fertilizer specified for lawns may also be used sparingly. Caution: Do not allow high nitrogen fertilizer to be in direct contact with the root-ball since it may scorch newly forming roots.

 

First and Second Year Most soils have the nutrients needed for bamboo to stay healthy. If you wish to encourage new shoot growth and provide a general feeding, apply fertilizer specified for lawns in the spring or fall. An ideal time is fall when the bamboo is storing energy for spring production. A good organic fertilizer is one part manure and two parts compost mixed lightly into the top inches of soil. Or follow the manufacturer's directions for a packaged organic fertilizer or slow-release fertilizer for lawns. Environment Tip: Organic and slow release fertilizers are recommended; they are absorbed more effectively by the plants. Avoid weed and feed products. These actions help prevent fertilizers and chemicals traveling with ground water runoff. For the third year and after, fertilize only if you want increased vitality, otherwise compost will be sufficient.

Mulching

Annually cover the planting bed with 2-3 inches of coarse mulch. Bark chips, leaves or grass clippings may be used to conserve water and prevent weeds. If you plant in late fall or winter, mulching is essential for protecting the roots.

Tip: Before mulching in winter, remove fallen bamboo leaves. The eggs of bamboo mites can survive the cold.

Pest Management
 

Bamboo Mites Older bamboo and those stressed by undesirable environmental conditions (e.g. too much sun for a shade-lover or too little water) are more prone to mites. A few types of bamboo like the Sasas are by nature more susceptible. The outdoor bamboo mite (schizotetranychus celarius) makes a fine web on the underside of leaves and the upper surface will have a rectangular patch or multiple patches of light yellow-green to tan. These are sometimes mistaken for leaf minor damage, nutritional deficiency or variegation.

 

Environmentally Sensitive Treatment Methods: Use a refined horticultural, spray oil or insecticidal soap. Read the label before spraying. For tall or large stands of bamboo a professional tree sprayer's service may be necessary.

 

Clear-cut For a severe infestation this may be the best, though most extreme solution. Remove all old culms just as the new shoots begin to leaf out. Then spray to prevent mites. Pest Management Tips: Avoid drought stress! Remove leaf litter when a mite problem exists. Do not use a dormant oil. Water heavily 24 hours prior to spraying. Avoid use of broad-spectrum pesticides, as they are more likely to kill predator insects and seldom result in eliminating mites. Predator mites may help but are not easily managed.

 

Aphids These translucent, soft-bodied insects often show up in early spring. They leave a sticky residue on the leaves which later turns to a sooty black film. This will remain until the leaves are shed the following year. You can reduce the aphid problem by pruning your bamboo to allow good air circulation and not over-fertilizing. Also, spray the leaves with a strong jet of water for a few days and wait for predators like birds and ladybugs to do their work. Some insecticide soaps kill aphids or the refined horticultural, spray oil for mites may also work. Check the label. Spray on an overcast day.

 

Snails or Slugs If you notice chewed out areas on new culms; slugs or snails are the likely culprits. Use one of the new animal and environmentally safe baits just as the new shoots appear.

 

Other Pests Herbivores such as goats, cows and horses find bamboo culms and leaves to be tasty so fence them out. Deer have not been a problem.

 

Control of Bamboo

Running Bamboo

For bamboo planted in the ground, there are a few ways to control the spread. The best method is rhizome pruning. Next best is a partial barrier, and third, a barrier encircling the entire bed. Above ground containers are other methods. Our guidelines are based on experiences in the Pacific Northwest where bamboo tends to travel horizontally in the top foot of soil, but may go deeper when encountering an obstruction. See recommended tools on our website or at the nursery.
 

Rhizome Pruning In July or August and again late October, edge prune along the perimeter of the bed. (Late October is sufficient if your bamboo is not in a confined space.) Do this by stomping a sharp, flat-bladed shovel to about 8-12 inches deep and remove rhizomes outside the cut line. Or work with a maddock, picking into the ground to pull up rhizomes. To monitor for rhizome spreading, dig a narrow trench 10 inches deep for a few feet along your borderline or do some trial picking into the soil. Tip: Planting in a one to two foot soil elevated mound can make the edge pruning easier.

 

Partial Rhizome Barrier Use this method if your bamboo is close to a fence or you need to give assurance to neighbors. Surround only one side of the planting bed to give rhizomes the other side for traveling, rather than having to grow deeper. Dig a trench and install the 40 mil high-density, polyethylene barrier. A depth of 28 inches is recommended, though a minimum depth of 22 inches is often used in clay or hardpan soil. Place barrier in the trench so it is straight down or slants slightly outward at the top to direct rhizomes upward. Leave up to 3 inches of barrier above soil line. Rhizomes will try to go up and over barrier. When they do, cut them off and remove. Follow the rhizome pruning technique twice a year on the open side and at least every other October inside the barrier (annually if the ground space is getting filled).

 

Full Rhizome Barrier If you choose to surround the entire planting bed be aware that barrier does not stop rhizomes, it redirects them. Bamboo within a barrier is a vigorous plant in a bottomless pot. Overlap the barrier at least one foot and hold it together with plastic glue. Or use stainless-steel, shelf holding strips on each side and hold them in place with screws and washers. Rhizome prune inside the barrier once a year. (New plantings or lots of space within the barrier may allow more time between pruning.) Tip: Extra care is needed to not cut into the barrier. Caution: Before you dig, call your public utilities company to have underground utilities located. This is usually a free service.

 

Raised Bed in a Box Use treated lumber to create a two- foot-deep by at least two-foot-wide, dirt-bottom box that could later be taken apart to remove rhizomes when the bed fills. Rhizomes might travel deeper if they become rootbound in this space. Use compacted soil in the lower foot and nicer soil on top. Being bottomless allows water to move through.

 

Decorative Pot Place bamboo in a durable, frost-proof pot or wood container with drainage holes. Or place a large plastic pot within a decorative pot with drainage. For mid-size bamboos a pot of at least 18 inches deep and 24 inches wide is recommended. Smaller bamboo may go in smaller pots. Move or protect the pots during a severe cold spell to prevent rhizomes from freezing. When bamboo becomes root-bound, pull it out of the pot and slice root-ball in half or thirds. Potting Tip: Do not use a container with a mouth smaller than the side walls. Rhizomes will fill in and may not be possible to remove.

Clumping Bamboo
 

Reduction of Clumping Bamboo If it ever becomes a wider clump than you want, use a wolverineTM shovel or tree spade; a bamboo slammer; or a saws-all to cut straight down through the rhizomes. This may be done any time of year though late winter is less apt to shock the plant if you wish to replant the divisions. Barrier material is not needed due to the limited amount of spread each year.

Pruning
 

Newly Planted Bamboo In general it is best not to prune newly planted bamboo. The leaves store energy for next year's growth. If the bamboo has a few tall culms it is okay to clip out the small bushy ones for appearance.

 

Second or Third Year and Thereafter Prune for appearance and for a healthy plant with lush foliage. The goal is to allow light to reach leaves in the top two-thirds and for air to circulate. When removing culms, cut them flush with the ground. Clippers, loppers and hand pruning saws are useful.

 

Mid-size and timber bamboo are usually pruned in spring before new culms shoot up, but any other time of year is also fine. First cut out old culms and those that are too short, too tall, or are leaning. On a grove older than 4 years also remove culms so those remaining are at least 6 inches apart. This makes room for the new growth in spring. When the new shoots appear, remove any too close to other culms or that are smaller than you want. To keep a shorter hedge, remove all large diameter new shoots. Early removal of new shoots saves having to dispose of a full-grown culm. New 6-12 inch shoots may be peeled, sliced and stir-fried for eating.

 

Shrub-size bamboo with winter damaged leaves may be selectively trimmed. Otherwise be patient and wait for old leaves to drop as new leaves appear. Culms may be removed as desired for appearance.

 

Dwarf bamboo Dwarf Bamboo with winter damaged leaves or a leggy appearance, may be cut back to about 3 to 4 inches just before new growth starts in spring (often April in the Northwest). The new flush of foliage will grow to the former height. Variegated varieties will have a brighter variegation. To maintain a low groundcover, cut or mow after the culms appear.