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  Planting

 

 

Basic Bamboo Information and Care

 

Bamboo Morphology

 

How Bamboo Grows

 

Plant Assessment

 

Soil Management

 

Planting

 

Fertilizing

 

Pruning and Containment

 

Bamboo Morphology

A brief description of the terms used to describe the major plant organs will help in understanding further discussions of bamboo.  Probably the plant parts we are most familiar with are the above ground stems called culms.  These are the trunk-like poles which bear the branches and leaves, and which we see used in construction, furniture and crafts.  The culms of most bamboos are hollow with solid nodes, the distinctive joints which are a bamboo trademark.  Branches originate at the nodes on alternate sides of the culm, and may occur in different numbers and configurations depending on the species.  Bamboos have two types of leaves: foliage leaves are the “green” food producing organs; culm leaves on the other hand, are attached at each node, and consist almost entirely of a sheath which serves to protect the tender, new shoots.  Rhizomes are specialized, under ground stems which bear many similarities to bamboo culms, including nodes and protective leaf sheaths.  There are two main categories of bamboo based on rhizome habit; running and clumping. Running bamboo rhizomes share many characteristics of their above ground counterparts; rhizomes have nodes and internodes, and buds occur along their length on alternate sides, wrapped in protective sheaths that are attached at each node.  These buds can produce new culms, or may branch off into new rhizomes.  A vigorous runner may produce rhizomes that stretch out 15’ or more in a single growing season.  Clumping bamboo rhizomes differ from running bamboos in that each one turns up through the soil, forming a new culm.  Clumpers have compressed internodes below soil level at the base of the culm where buds occur that form the new rhizomes/culms.  For both running and clumping bamboos, the newly emergent culms are referred to as shoots.

How Bamboo Grows

The stature and wood-like properties of the canes might lead one to believe that bamboo grows like a woody shrub or tree, however, bamboos are members of the grass family so their vascular system and growth process is vastly different.  Woody plants increase in height/length by cell division at the tips of branches and roots, and in girth by cell formation in the cambium, the layer of life between the wood and the bark.  As trees grow, their branches and roots get longer, and their trunks and stems get fatter.  Bamboo shoots, on the other hand, emerge at their full diameter and grow to their full height in a matter of weeks to months depending on the species and the environment; neither the girth nor the height of the culm will increase after the shooting process is complete.  As the new shoots elongate, the protective leaf sheaths drop as branches then leaves emerge.  In some bamboos the leaf sheath may persist, and in others, branching out occurs the following year.  Most bamboos have short lived foliage leaves which are cyclically shed as new leaves unfurl so that the foliage remains “evergreen.”  Depending on the species, leaf yellowing and leaf drop may be more noticeable at certain times of the year, which is a normal part of the growth cycle.  The culms and rhizomes are relatively short-lived as well.  In a mature grove, the culms of many bamboo species will start to decline in vigor after 3-5 years, with a life span up to several years longer.  Rhizomes seem to lose their vigor after only a few years.  Over time, a grove will produce copious amount of weed-suppressing, organic duff in the form of leaves, sheaths, dead branches and culms. Rhizomes and fibrous roots also add organic matter to the soil as they die and slowly decompose.  

 

Growth cycle

In general, temperate bamboos respond to warming temperatures and day length, sending up a wave of new shoots once per growing season in spring.  However there are many exceptions to this pattern; some species shoot in fall, some have two shooting periods, and others seem to send up shoots all growing season.  Once the shoots have reached their full height, branches develop and leaves unfurl.  The leaves photosynthesize the bulk of the food produced during the year over summer.  Sugars are transported and used for food, or converted to starches and stored, especially in the culms and rhizomes, for the following year’s shoots.  It is commonly held that rhizome growth largely occurs in late summer and fall, after the shooting process is complete.  However, I have observed in my own plantings that rhizome growth can occur concurrently with shooting and throughout the growing season (until soil temperatures cool and days shorten in October).  The buds along the length of the rhizome initiate new shoots for the following year during this period as well.  After October and through winter, temperate bamboos are mostly dormant.  In the mild winters of my region, however, leaves continue to unfurl during warm spells all winter long, and the culm buds initiated earlier in the growing season continue to develop.  In spring, the cycle starts over once again with the emergence of new shoots. 

 

Plant Assessment – Container Propagations

You will benefit from understanding how to assess a bamboo’s stage of development both in terms of choosing a plant to purchase, and in preparation for planting.  Based on my experience dividing and growing thousands of propagations, I classify container plants into five major stages of development, each with distinctly different needs that affect planting technique and post-transplant performance.  Large, field dug divisions fall into a class of their own because their size affords them an energy storage capacity that makes them nearly bullet-proof if properly dug.  In fact, I have never seen a large division fail that was properly cared for.  Even in the rare event that the culms die back completely, there is so much energy in the rhizome that it will send up new growth eventually.  

 

New Divisions.  This term refers to plants that have just been removed from containers and divided, or for rhizome propagations in their first season of growth.  In either case, plants in this stage are the most tender and susceptible to plant stress or loss.   A larger root ball will generally sustain the top growth better than divisions with a smaller root ball, and will be quicker to establish.  Divisions with a small root/rhizome ball, and even more so, rhizome propagations, lack the food reserves to grow feeder roots, culms and leaves all at the same time.  Plants will generally utilize energy reserves to produce/replace the food-producing organs first (i.e. new shoots that will branch and leaf out) with new root growth following.  New divisions need optimal conditions to survive this stage, and should never be disturbed or removed from their containers.  Leaves are especially susceptible to desiccation due to the lack of a developed root system, so they should have protection from hot sun, wind, and low humidity.

 

Stabilized Plants.  I use this term to describe new propagations that are “out of the woods”, and able to sustain healthy foliage, but have very little new root growth.  If lifted from the pot, the soil or potting mix will fall away from the root ball exposing tender white tips of new root growth. Depending on the species, propagation technique and size, environment and time of year, it may take 1-6 months for a new division to become stabilized.  Stabilized propagations can be planted out, but it is probably safer to let them remain in the pot until roots can develop further.  If it is necessary to plant a stabilized division, then take care not to disturb the root ball any more than is necessary.  Be gentle!

 

Well Rooted Plants.  I use this term to describe plants that have a root system that has just grown out to the edges of its container.  If removed from the pot carefully, root development is sufficient to hold the soil or potting mix in the shape of the container, but can easily be removed from the root ball.  Well rooted plants can be placed directly into the planting hole without any special treatment.

 

Fully Rooted Plants.  These plants have fully developed roots crowding the edges and bottom of the container, reminding me of cooked spaghetti noodles.  The roots are healthy, pliable, and white in color.  Young rhizome may also be starting to wrap around the inside of the container.  Fully rooted plants will benefit from root pruning and separation at the time of planting.  I use the dull “hook” side of my bypass pruners to tease apart the roots all along the sides and the bottom of the container.  I also use the pruners to trim off any broken or tangled roots. Rhizomes can be teased away from the root ball and stretched out in the planting hole, or trimmed to a node past a point of breakage.

 

Root Bound Plants.  At this stage, aging and dead rhizomes are wrapped around the container perimeter, and old roots crowd the bottom and sides of the container.  Together they form a dry, woody shell in the shape of the container.  Fibrous roots in the interior of the container also age and die, becoming a congested, twiggy mass.  With little room for new root growth, plants soon exhibit a marked decline in vigor.  However, root bound bamboos can survive and produce new shoots (thought stunted and less vigorous) for years, even in neglected containers.  If watered and fertilized, they can look presentable, even healthy if the old, stressed culms are removed regularly.  When planting root bound bamboos, I remove the whole outer layer (dead) of woody root and rhizome, which stimulates new growth and speeds the establishment of the planting.  For smaller plants, a pair of pruners or loppers will usually do the trick.  For larger plants I use a sawzall with a wood pruning blade to slice off the woody material.   Even without pruning, a root bound bamboo will survive and eventually thrive once planted out. 

 

Choosing a Plant.  Myriad factors affect how quickly a container bamboo propagation will establish and spread in the landscape.  In my experience, the best performers are well rooted or fully rooted bamboos.  When transplanted and cared for properly, they “hit the ground running” without experiencing transplant shock.  Root bound bamboos are my second choice.  Even if the foliage may not look particularly vigorous, root bound plants can be as fast, or nearly as fast to establish as a well-rooted bamboo, especially when they are root pruned at planting.  Stabilized propagations can be good performers as well, but may be as much as a year behind a fully rooted, or root bound plant with the same amount of top growth.  You may want to avoid them if you desire immediate results in your landscape.  New divisions are a real gamble due to the risk of plant failure, and should probably be avoided unless you have the proper conditions to care for the plant until it matures.  Of course, price is a factor as well, so even a small, new division can be a good deal if it’s free or priced accordingly.  By the same token, be prepared to pay more for plants that have been cared for longer, and are more fully developed.  If you are buying from a nursery in person, don’t be shy about asking how old the division is, or getting someone to help remove the plant from the pot to inspect its the root development.  If you are buying bamboo in spring to early summer, check to see if the new season’s shoots are emerging.  If new shoots of any size are present, chances are it is a healthy, established plant.  If the new shoots have a larger diameter than the old growth, it’s likely that it’s at least a year old and a good bet that it will perform well. 

Soil Management

A detailed discussion of the complexities of soil management is beyond the scope of this article (and my expertise).  My intent is to encourage you to learn about your soils by touching on a few rudiments of soil management.  Extension offices of universities and county Conservation Districts have many free resources and programs.  Books, magazines and garden shows often have recommendations for improving specific, local soil conditions.  You don’t have to be a soil expert to grow great bamboo, but it certainly doesn’t hurt to have a basic understanding of how certain soil characteristics may affect your bamboo.  This is especially true in regions where soil characteristics are poorly suited to gardening. 

 

Soil pH.  This term refers to the acidity of the soil, and is measured on a logarithmic scale of 0 – 14, (i.e., a pH of 5 is ten times more acid than a pH of 6) with 0 being the most acidic, 7 being neutral, and 14 the most alkaline.  Soil pH affects the availability of various elements which are vital to plant growth.  Nutrient availability is optimal for most plants at a pH between 6.5 – 7.  Some bamboos are more suited to alkaline or acid soils than others, but most will do well in soils that range from a pH of 5.5 – 7.5.  If your soil pH is beyond this range on either end of the scale, you are probably in a region notorious for the condition.  Local strategies and products to implement them should be easy to find with a little research.  The soil/pH relationship is very complex, as a multitude of factors affect the soil pH of a given region. Broadly speaking, regions with high rainfall tend to have soils with a lower pH (acid); arid regions tend to have soils with a higher pH (basic).  Soil texture, mineral and organic content, water quality, and fertilizers also impact soil pH. 

 

Some common strategies for increasing soil pH include the addition of various lime products or wood ashes.  The addition of mushroom compost during bed preparation (which can have a pH as high as 8) or post-planting as a mulch can also raise soil pH.  For basic soils, common strategies to lower the pH include the use of sulphur products including: elemental sulphur, aluminum and iron sulphates, and sulphuric acid.  Chemical fertilizers such as ammonium sulfate or urea can also have an acidifying effect.  Incorporating copious amounts of organic material, especially peat moss with a pH below 5, may be more effective and longer lasting than a strictly chemical approach.         

 

Soil Texture and Organic Content

Soil texture refers to the proportion of sand, silt and clay in a given soil; sand particles are the largest, clay particles are microscopic and silt somewhere in the middle.  A perfect loam would consist of 40 percent sand, 40 percent silt and 20 percent clay.  Loamy soils are desirable because they typically have the porosity necessary for water and nutrient infiltration/drainage (sand) as well as the good water and nutrient retention (silt and clay).  Soil texture has to do with the mineral content of a soil, not its organic content. A quality soil will have about 45% mineral content (i.e. sand silt and clay content combined).

 

Organic matter consists of both living (i.e. fungi, bacteria, worms, insects) and dead plants and animals, as well as their byproducts.  Organic matter is absolutely vital to soil health; it provides plant nutrients, improves water/nutrient retention and availability, aeration and drainage, just for starters.  An ideal loam soil would contain about 5% organic matter, but it’s virtually impossible to overdo well-composted organic amendments.

 

Water & Air

Water, of course, is a fundamental soil component since it is critical to the very existence of plants, and is largely obtained from the soil via tiny root hairs.  Most commonly associated with its role in photosynthesis, (the process of producing carbohydrates from water and carbon dioxide) water is a major component of plant tissue required for plant metabolism in general, and acts as a courier of nutrients and food to various plant organs.  Air contains nitrogen, oxygen and carbon dioxide which are all fundamental to plant metabolism.  As a soil element, air is critical to plant roots for respiration, (the process of combining sugars with oxygen to create energy for growth). 

 

With some exceptions, most plants (including bamboos) do best in soils that contain equal proportions of air and water.  With too much air (i.e. sand soil w/low organic content) the soil is unable to hold enough water for plants to survive and thrive.  With too much water, (i.e. swampy areas, or clay) air is displaced, and roots don’t get enough oxygen for respiration, which can stress or kill the plant.  In a perfect loam, air and water comprise half of the soil content, 25% air and 25% water.     

Planting

Planting Times.  The best time to plant will vary depending on many factors, including the region and the bamboo species.  In mild regions, a healthy, well-established propagation can be planted successfully year around.  For most regions, however, late summer/early fall is the best time for numerous reasons.  For one, new culms will be finished shooting, so the risk of new shoots aborting or breaking is eliminated.  Also, cooling air temperatures, the warmest annual soil temperatures, and increased rainfall can create ideal conditions for bamboos to establish before the going dormant over winter.  Late spring is another great time to plant – warming air/soil temperatures and plentiful rain water provide good growing conditions for new plantings, however, new shoots can easily be snapped, or abort due to transplant stress.  Early fall and late spring offer the distinct advantage of being the best times to fertilize. Summer can be a good time to plant in milder regions, however, plants must be watered regularly during warm, dry spells.  In very hot, arid regions, you may want to avoid summer planting unless you can provide regular irrigation, increased humidity, and protection from hot afternoon sun.  Winters can also be tough on transplants, and if you live in a region where winter temperatures customarily drop low enough to freeze the ground solid for several days, wait until spring to plant if you miss the late summer/early fall planting window.  Even in warmer regions, heavy, (clay) wet soils can “suffocate” small transplants over wet winters.  I usually keep smaller plants in containers over winter so I can more easily control moisture levels, and have the ability to bring the plants under cover during cold, dry weather.  Don’t expect young plants to have the same cold hardiness (planted out, or in containers) as well-established, mature plants.  Mulch container plants to stabilize the temperature of the root ball during cold snaps, or bring them in a garage/cellar where they will receive a few hours of light each day.

 

Soil Preparation.  Fortunately, bamboos and most other plants do not require “ideal” soils to grow, and even thrive.  If you have average garden soil, your bamboo will probably do well if you simply dig a hole, plant the bamboo so the top of the root ball is level or a little below the surrounding soil level, then back fill and firm the soil to remove any air pockets around the root ball.  If the soil is very dry, it is a good idea to water the hole and surrounding area before planting, then again after planting to settle the soil and soak the root system.  Plants will benefit from a top dressing of 3” of mulch to help hold moisture, discourage weeds, and provide nutrients.  Bark or wood chip mulches effectively suppress weeds, help to retain heat and moisture, but can actually deplete nitrogen from the soil as they decompose.  I use garden or manure composts and they work well for me.

 

For compacted, sandy, or clay soils, it will help to first loosen the soil in the entire planting area with a shovel or rototiller.  Very sandy or clay soils can be improved with organic amendments (i.e., garden or manure composts, peat) by turning with a shovel, or rototilling organic matter in a few inches at a time.  It will take at least a 6” layer of organic matter to make a significant improvement to soil characteristics.  Organic amendments will help to hold water and nutrients in sandy soils.  In clay soils, they will help aerate and improve water movement through the soil.  Mounding the amended material inside the planting bed into a berm will also improve drainage and workability of clay soils, as well as raise the soil temperatures earlier in the growing season.  Bamboo planted in a berm is also easier to contain by rhizome pruning.  Composted manures used to improve soil characteristics, will also serve as organic fertilizers.  Do not amend clay soils with sand, as it will take on the properties of concrete!

 

Watering.  If the soil is very dry, it is a good idea to water the hole and surrounding area before planting, then again after planting to settle the soil and soak the root system.  After planting, water regularly until the plant stabilizes.  A good rule of thumb for average soils is once a day the 1rst week, once every 2 days the 2nd week, etc., for the first month, then watering as needed to keep soils from drying out.  The idea is to keep the soils moist but not soggy, so adjust watering to meet the site conditions.  After the first growing season, most bamboos will do very well with weekly irrigation, and some are quite drought tolerant.  In hot, arid regions, as much as daily watering may be necessary, as well as misting to increase humidity.

Fertilizing

There is a lot of anecdotal information out there about how to get great results with different fertilizing methods.  Because there are so many different success stories, it’s impossible to say what portion of the fertilizing program is responsible for the success, or if it’s the fertilizing program at all.  The best way to fertilize is to have a complete soil test done first, then supplement with a fertilizer that will compensate for any nutrient deficiencies. Of course, one needs a thorough knowledge of a plant’s nutrient needs and the ability to diagnose plant symptoms in order to know if a nutrient is “deficient” or not.  Otherwise, a fertilizer program becomes a lot like adding fuel and oil to a car without ever checking the gas gauge or the dipstick. Frankly, most of us aren’t able or willing to take the time and effort to become soil/nutrient experts – we just want our bamboo to grow healthy and beautiful!  With that in mind, I recommend we take a "less is more" approach, using a few key guidelines to minimize negative impact to our environment:

 

  • Use organics whenever possible.  This is a productive way to recycle organic waste (i.e. well-composted manures produced from livestock, garden or recycled urban compost) and organics are less likely to be over-applied, or leach nutrients into surrounding areas.
  • When using chemical fertilizers, apply conservatively, especially if your bamboo is doing well already.
  •  For average garden soil, nitrogen is the nutrient supplement your bamboo will most likely benefit from.  Forget about high phosphorous/potassium fertilizers in winter to encourage root growth, unless you have a soil study in hand showing a deficiency of these two elements. 
  • Fertilize during the growing season only.  After the soils cool and light levels diminish, plants are mostly dormant, so unused nutrients that are mobile in the soil (i.e. nitrogen) will tend to wash out over winter.  This is less a problem with well composted manures than with hot manures and most chemical fertilizers.

 

 

Manures

For bed preparation prior to planting, I amended my silt loam by tilling in a 12”-15” layer of composted horse bedding (manure and urine-soaked wood shavings) which I obtained free from a local stable.  Garden compost, or other well-composted manures will work as well.  For established plantings, I apply a 3”- 6” top-dressing of composted manure once per year, usually in spring before shoots emerge, but can be done any time during the growing season (in my region, May through the end of August).  Mulching at the end of summer has the added benefit of holding the heat longer, and adds a protective layer of insulation to the root zone.  Established groves create a large amount of their own leaf litter which should be left to enrich the soil and suppress weeds.

 

Chemical Fertilizers

There are a multitude of fertilizers that can be used on bamboo, including granular, slow release pellets, and quick release, water soluble crystals.  Regardless of the form, each will have a three-number rating that refers to the amount of nitrogen, phosphorous, and potassium (respectively) per 100 pounds of fertilizer.  For example, a 100 lb. bag of 20-20-20 fertilizer would contain 20 lbs. each of nitrogen, phosphorous and potassium; these are the big 3 macronutrients most likely to cause problems if deficient in the soil, however, many fertilizers contain other macro and micro nutrients as well. 

 

Water soluble fertilizers may be the best choice for residential applications because they are readily available, have easy to calculate rates, and are easy to mix and apply (i.e., in a sprinkler can or garden sprayer). I have used Miracle Grow All Purpose 28-8-16 for container plants, (among others) and can vouch for their claim that it won’t burn if used according to directions, even it hot weather, and with new divisions.  Plus, the plants seem to thrive, even in soiless mixes that do not contain any of their own nutrients.  Be sure to follow the directions regarding application rates to avoid wasting and minimize environmental contamination. 

 

I prefer using a granular fertilizer for bamboos planted in beds.  For my groves, I have used Scott’s Turf Builder, 27-3-4 with iron and micronutrients.  This is a granular fertilizer that has a release rate of up to 2 months, so I can apply it in late August with confidence the nitrogen will be used up by October when the soils have cooled and the bamboo is mostly dormant.  I have calculated the following amounts based on nutrient requirement data for turfgrasses which have been extensively researched and documented.  Not perfect, but I am confident they are on the conservative side, safe for your bamboo and friendly to the environment.  Keep in mind that every fertilizer program should be site/plant specific; it is impossible to make broad recommendations with anything close to accuracy. For example, the nutrient uptake of a timber bamboo with a leafy mass reaching 35’- 40’ high will be far greater than that of a dwarf bamboo covering the same square footage, but only a few inches tall.  These recommendations are meant to be a safe starting point for most residential gardens, but may or may not actually improve the growing performance of a bamboo in a given situation.  

 

All amounts are given in pounds of 27-3-4 granular fertilizer per 1000 square feet, so you will need to calculate the correct amount for smaller or larger areas, (see example below) and you will need a scale in order to measure the quantity of fertilizer to use. 

 

Bamboos 6 inches – 3 feet tall (Dwarf)

Rate: 3.7 lbs. 27-3-4 fertilizer/1000 sq. ft. each application

Number of applications: 3 per year

Timing: Make your first application in spring when signs of active growth first appear (late march in my region).  Make the second application about 60 days later.  Make the last application August 1rst so that the nutrients are used up by the time plants go dormant in October.

 

Bamboos 7 feet  20 feet tall (Medium)

Rate: 3.7 lbs. 27-3-4 fertilizer/1000 sq. ft. each application

Number of applications: 5 per year

Timing:  Make your first application April 1rst, and successive applications every 30 days (the 1rst of May, June, July, August) 

 

Bamboos over 25 feet tall (Timber)

Rate: 7.4 lbs. 27-3-4 fertilizer/1000 sq. ft. each application

Number of applications: 5

Timing: Make your first application April 1rst, and successive applications every 30 days (the 1rst of May, June, July, August).

 

Application.  After the correct amount of fertilizer is calculated,  scoop out and weigh the appropriate amount for the bed you are fertilizing.  I hand-sprinkle the granules through the bed, making several, light applications; this helps to cover the ground more evenly.  Also, if the bed is sloped, I make a heavier application at the top of the bed since nutrient will be carried downhill with watering.  When handling fertilizer, I recommend wearing latex gloves or other hand protection, as well as eye protection.

 

Calculating amounts for areas larger or smaller than 1000 square feet.  To do this, first multiply the approximate length and width of the bed (in feet) to determine the square footage.  Then take that number and multiply it by the recommended rate (pounds of 27-3-4 fertilizer).  Finally, divide that result by 1000.  The final number is the number of pounds of 27-3-4 fertilizer to use for your bed. 

 

As an example, let’s use a 10’ x 50’ bed with a recommended rate of 3.7 pounds of 27-3-4 fertilizer per 1000 square feet.  First, multiply 10*50 to determine the square footage of the bed is 500 sq. ft.  Then multiply 500*3.7 for a product of 1,850.  Divide this number by 1000 to determine the recommended amount of 27-3-4 fertilizer is 1.85 lbs. per application.

 

Putting it into perspective

1.85 lbs of Scotts 27-3-4 is about 5 cups, so a 37 lb. bag of Scotts 27-3-4 contains nearly 20 applications at this rate.  Using the 500 sq.ft. bed in the example above, you could fertilize a dwarf bamboo (6" - 3' tall) for over 6 growing seasons; a medium-size bamboo for nearly 4 growing seasons; a timber bamboo for 2 growing seasons.

 

 

Pruning and Containment

Safety first!

Before performing tasks in the grove, you should have the appropriate safety attire for the job.  Even when using manual garden tools (i.e. saws, pruners, shovel or mattock) you should at least be wearing gloves, safety glasses and work boots/shoes.  Safety glasses are especially important for protecting eyes from branch ends, leaves or flying debris. 

 

Pruning overview

The two main reasons I prune are to control the spread of bamboo, and to improve its health and vigor.  Improving health and vigor will also improve the ornamental value of the planting, and makes it easier to access for future grove maintenance.  Pruning techniques and timing will vary depending on the kind of bamboo being pruned, and the purpose of your pruning.  I recommend leaving all foliage-bearing stems until the planting is well-established, at least until the second, probably the third or fourth growing season after planting. 

 

I divide bamboos into two categories based on the pruning techniques employed; dwarf and small bamboos from one to ten feet tall are in the first category, and anything larger in the second category.  Once you understand what needs to be done and why, you can employ the proper pruning techniques at the right time, based on which category your bamboo falls into.  Below, I outline the pruning techniques I use for each category, their effects, and the best time to perform them.

 

Bamboos 1’ – 10’ tall

There are two basic pruning techniques I use on smaller bamboos: coppicing, which is removal of all vegetative growth back to ground level; and rhizome pruning, which involves the heading back of the underground rhizomes to the bed border.  Coppicing is used to rejuvenate the planting.  As culms age and lose their vigor, branches become less productive and the percentage of damaged and diseased leaves increases.  As older and dead culms become interspersed with vigorous stems, the planting loses some of it lush, green appearance.  If the stems are cut back to ground level, the plant responds by sending up a wave of vigorous, new shoots (albeit smaller) that keep the planting looking fresh and healthy.  Regular coppicing will also control or even eliminate bamboo mite infestations without any pesticide application whatsoever.  Rhizome pruning, in contrast, is used to contain the planting within the bed border. 

 

Coppicing.  For smaller areas, I use a pair of bypass pruners to snip each stem off at its base.  For bamboos with very thin stems, like Sasaella ramosa, quality, hedge-type shears will work as well and are faster.  For large scale ground covers, some suggest mowing, or using a commercial quality weed-eater or brush whacker.  The key is to remove all, or as much as possible of the above ground stems and foliage.  Coppicing is best done just before new shoots emerge.  Depending on the bamboo, early spring to early summer is usually the best time.  By waiting until just prior to shoot emergence, you will minimize the time spent viewing the hole created in the landscape.  In addition, the delay prevents the exposed soil from warming too quickly, (in which case, shoots may emerge early and be damaged by frost) and reduces the opportunity for weed seeds to germinate.  Once the planting is established, coppicing may be performed every 1-3 years depending on how the bamboo is performing.  That’s all there is to it - cut back to the ground and wait for the beautiful new shoots to emerge!

 

 

Rhizome Pruning small bamboos.  I perform rhizome pruning in late spring or early summer before rhizomes have really spread out and had a chance to get woody.  It’s a good idea to check again after the growing season (the end of October in my region) to get any new growth or strays.  All that you’ll need for smaller bamboos is a light mattock or pick, perhaps just a shovel if the digging is easy, and bypass pruners.  I start by creating a shallow furrow along the bed edge, using the “wide” end of a mattock like a hoe to pop up rhizomes as encountered.  Rhizomes of most bamboos are quite shallow providing they don’t encounter an obstruction, so you should find most of the rhizomes in the top 4”-6” of soil.  If the rhizomes haven’t moved too far beyond the bed border, they will be tender and easy break with the mattock, or cut off with pruners.  Or, if the soil is soft, you may be able to shear off the tender rhizome tips by using your foot to drive a shovel straight down into the soil.  If you use overlapping cuts the full depth of the blade, you should do good job of getting all the rhizomes.  If the rhizomes have established beyond the bed perimeter, you may be digging through a network of tough, woody stems.  In this case, I recommend using the mattock like a hoe to scrape/pry out the rhizomes, and then chop them with the cutting edge of the mattock.  Or, you can use the mattock to pry the rhizomes out, and then cut them with the pruners.  After cutting the rhizome, I try to completely remove any rhizome pieces that are outside the bed area; small bamboos are especially notorious for propagating themselves from bits of rhizome, even if left over winter.  In spring, any new shoots popping up will show you where you missed!  The key to containment is religious rhizome pruning.  Once the plant has spread and established beyond the bed border, you will have a difficult chore ahead, and it may take several years before all stray rhizomes are removed. 

 

Bamboos over 10’ tall

Pruning techniques for larger bamboos are similar, but involve more options, a little more technique and a little more work.  Like their smaller counterparts, large bamboos will benefit from periodic removal of older and failing culms.  This stimulates the growth of and makes room for new shoots, as well as reducing disease, and pest populations.   Unlike smaller bamboos, only a portion of the culms are removed in a given growing season.  I do not recommend coppicing (removal of all the culms) except in extreme situations, such as renovating to control mite infestations, or in preparation for complete removal of a bamboo.  New bamboo shoots may also be removed to improve spacing, or harvested for the table.  For culm and shoot removal, I use thinning cuts - removal of the culm or shoot at or below ground level, very close to its point of attachment to the rhizome.  Thinning cuts may also be used to remove dead branches, (at their point of attachment to the culm) or to expose ornamental features of the culms.  Heading cuts, (partial removal of a culm, branch or rhizome) on the other hand, are used on culms to remove broken tops, or to control height; branches may be headed back to control size or to shape for formal pruning (i.e. shearing).  Heading cuts are also used to shorten rhizomes for containment.

 

Shoot Thinning.  Shoot thinning is one of the first tasks of the growing season - spring to early summer, depending on the bamboo.  If your goal is to have the largest culms possible in the grove, (mine certainly is) then remove the smaller shoots as necessary to maintain ample spacing between the new shoots and mature culms.  With frequent exceptions, I try to keep shoots and culms at least 12” apart, for mature timber bamboos, and for smaller bamboos, 4”-12”.  In established groves, the largest shoots tend to emerge first, which makes it easy to select the smaller shoots for removal after the larger shoots are well up.  I remove smaller shoots as soon as the tips break the soil by snipping them off right at ground level, causing the whole shoot to abort.  If you are harvesting shoots for the table, you may want them to grow a few inches tall before harvesting.  Also to get a larger, edible portion, try scraping the soil away from the shoot and cutting it as close to the rhizome as possible.  I use pruners or a sharp utility knife for shoot thinning/harvesting, but I am sure that commercial harvesters use more effective tools and techniques.

 

Culm thinning, according to conventional wisdom, is best performed just after the new shoots have fully emerged and finished leafing out – usually mid-summer to early fall depending on the bamboo and the environment. While this is probably the best time to thin the grove, bamboos can be quite forgiving about the time of year they are thinned.  I perform bamboo thinning virtually year around, simply because that’s how long it takes me finish all of my plants.  Still, I perform the bulk of the work between June and January, but I never do any major thinning in a grove that is actively shooting. 

 

Like coppicing, thinning involves the complete removal of the culm at ground level.  Depending on the size and spacing of the culms, a variety of tools may be used to accomplish the task.  I use hand pruners for very small culms, and a sawzall for larger culms.  A very sharp, manual pruning saw will work as well.  Loppers can be used too, but are difficult to maneuver into the interior of a planting, and won’t work on culms larger than about 1” in diameter.  If you can afford it, an 18 volt, battery-operated sawzall is the absolute best tool for this task.  It’s portable, easy to maneuver in the grove, cuts through canes easily, and blades are easy and affordable to change once they have dulled.

 

I start by removing the dead and broken culms from the perimeter of the grove first, working my way toward the interior.  Once the obvious culms are removed, I thin out tightly-spaced culms by removing the oldest, smallest culms to provide the desired spacing (discussed above).  Culm stumps can be smashed with a small sledge to speed decomposition and prevent leafing out at ground level.   A good rule of thumb is to remove no more than 1/3 of the canes in an established planting.  Removing more than 1/3 may increase vulnerability to winter damage, and/or compromise the size of the following year’s shoots.

 

Branch thinning to remove dead, dying or broken branches may be performed at any time of the year using a pair of bypass pruners, loppers, or a saw for thicker branches.  Remove the branch as close to the culm node as possible to avoid leaving stubs which can be extremely hazardous to skin and eyes.  If you are pruning to expose ornamental culms, it is easier to remove the new branches just as they start to emerge.  These tender stems are much easier to remove than mature, woody branches.  In fact, you can easily snap them off by running your hand down the culm in a chopping motion, if you are in a hurry.  However, this technique can sometimes damage the culm, so I usually take the extra time to snip them off with a pair of bypass pruners, right at the culm node.

 

Heading Back Culms and Branches.  Culms may be headed back as necessary, to remove the top of a broken or permanently leaning bamboo culm, both of which are frequently caused by heavy snow or ice loads.  For broken culms I make my cut below the break, just above a node.  If the break is below the lowest branches, I just remove the culm at ground level.  For leaning culms, removal of a top portion will usually lighten the load enough that the culm springs back upright.

 

Culms may also be headed back for height control, (i.e. under power lines or in areas with height restrictions) or to create a formal, flat top.  The same goes for branches, which may be headed back to reduce size, or sheared to create formal, geometric shapes.  I do not recommend these practices because they destroy what to me is the natural beauty of the bamboo (my opinion only, of course!).  If you are faced with a height limitation, I recommend planting a bamboo fitted to the site.  If you want to create a formal hedge or geometric shapes, there are plant forms of every size and shape from genera that are highly prunable and better suited to this purpose (i.e. Buxus, Taxus, Prunus, Thuja, and many others).

 

Rhizome pruning large bamboos is essentially the same as for dwarf bamboo, but on a larger scale.  Depending on the bamboo, I perform the first round of pruning in late spring or early summer as new rhizomes start to grow.  At this early stage of development, rhizomes can be easily broken or cut off, so it’s a simple matter to root them out and head them back at the bed border.  To do this, I work my way along the edge of the bed, using a mattock to scratch through the surface and expose rhizomes.  Then I sever the rhizome at the bed edge with a shovel tip, or the cutting edge of the mattock; for rhizomes that have grown beyond the bed border and become woody, I use bypass pruners or loppers to make the cut.  For large areas with room to maneuver, I rototill along the bed edge to break off the rhizome tips.  Any that are missed by the tines, I go back and cut with loppers.  I perform the second round of pruning again in fall, after the soil temperatures have cooled and the rhizomes are through growing for the season.  Pruning just once in the fall will work, but it might mean chasing down an unchecked rhizome well into a neighbor’s yard, a drain field, or any number of undesirable places – rhizomes from a mature planting can grow 15’ or more in a single growing season, so beware.  It will also take more work since the rhizomes have had the time to harden, as well as to root out, which makes both digging and cutting much more difficult.

 

 

 

 

 




   

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