This handout is based on the presentation by James Clever and Ian Connor at the 2005 American Bamboo Society’s National Conference in Houston, TX.

 

This is a lot of fun, and yet a very vital process.

The following considerations all need to be taken into account.

 

• Appearance (culm colour, diameter, texture and / or distortion; foliage size and with / without variegation).

• Maximum height.

• Light tolerances (full sun, afternoon shade, or full shade).

• Clumping versus spreading (key consideration for maintenance).

• Cold hardiness.

• Water requirements.

• Uses in garden as canes or for building and crafts projects.

• Area available for the bamboo.

• Above ground:  This involves overhead power, cable, and telephone lines, obstructions from other plants, whether a view is to be obstructed or not, or to act as a focal point.

• Below ground:  This includes utilities (electric, gas, sewer, sprinkler systems) concrete footings for fencing, walls.

It is best to ask your local specialist nursery person or gardener for help on the best choice.  Some mainstream nurseries are not even aware of whether the plant is a clumper or spreader!

 

 

Timing: Bamboos can be planted in all but the coldest of months.

 

Soil:  Bamboos require a soil rich in humus, yet free draining, especially in the winter.  If the soil is too sandy, add rich organic material; if too heavy, break it up with grit to increase air porosity.  As bamboo is a surface rooter, only the top foot of soil need be amended.  Bamboo can be planted one or two inches deep in soil without harm, but must be heavily watered in.

 

• Ground covers = 18 inches apart (closer for immediate impact)

• Clumpers = 5 to 6 feet apart

• Spreading shrubs = 3 feet apart

•   Spreading timbers = 3 feet (1 gal.), 5 to 6 feet (5 gal. to 25 gal. specimens)

 

Spread two to four inches of mulch (hemlock has no splinters, while Douglas fir has plenty!) around the bamboo after planting.  This replicates the forest leaf litter that bamboo finds itself in its native habitat.  Mulch helps reduce weed infestation, increases water retention, slowly releases nitrogen and generally enriches the humus content of the soil.

 

• Newly planted containerized or field dug bamboos are dependent upon regular watering for several years to create a deep wide feeding root system resulting in a more drought tolerant plant.

• To achieve the full potential of the plant watering beyond establishment is essential.  Bamboo requires regular deep irrigation (once to twice a week) throughout the growing season (March to October).

• In heat waves, bamboo will need heavy watering three to four times a week.

• Misting foliage of newly planted bamboos is very helpful in increasing localized relative humidity, thereby reducing transplant shock, suppressing outbreaks of aphids and even bamboo mites.

• Containerized bamboo may require watering daily in heat waves along with misting their foliage.

• Clumpers (such as Chusquea, Borinda, or Fargesia species) require far less water than spreaders, especially the giant timber bamboos (Phyllostachys).

 

Under watered bamboos  

Water stressed bamboos often abort new culms (living canes) and their foliage rolls inward (old foliage on broad leaved species turn yellow).  If not watered immediately, the foliage becomes crispy and dies.  If the plant can recover, it can take quite a while.

 

These can turn yellow and suffer leaf tip dieback.

It is normal for bamboo in mid spring to shed some old foliage at the onset of new growth.  This should not be confused with under watering.  Some clumpers also shed some foliage in early winter as a strategy against the cold.

 

Being a woody grass, bamboo has an almost insatiable lust for nitrogen.  So, most high nitrogen fertilizers, especially those meant for lawns, are ideal.  

 

Added iron maintains lush blue green foliage.  Bamboo require fertilizer from early spring until late fall. 

 

Manufactured fertilizers can provide very quick, or regulated slow release of nutrients over the growing season.  If over applied, such fertilizers can pollute the soil and water systems and even cause leaf burn often resulting in defoliation.  If too much nitrogen is applied at the end of the growing season the resulting new soft growth could be prone to frost damage during the winter months.

 

By contrast, organic fertilizers release nutrients more slowly, preventing leaf burn and pollution of the soil and generally creates a stronger healthier plant.

 

As an additive, micorrhiza can boost uptake of water and nutrients whilst being supplied with nutrients from the host plant, that is the bamboo. It is a highly successful symbiotic relationship whereby the fungus acts as an extension to the root system of the bamboo.

Micorrhiza is of great benefit added to newly planted bamboo, as well as an additive in an organic fertilizer.

 

It is desirable to maintain an airy open canopy to reduce aphid attacks and create easy access, especially with timber bamboos.

Remove thinning out the dead, damaged, leaning and weak culms in early spring, or wait until new growth has fully extended and leafed out before pruning (up to 30% on mature stands to recycle culms roughly every 3 to 4 years).

Always cut culms flush to the ground and never leave branch stubs on the culms; bamboo is very tough and rots slowly, so can be painful if ‘spikes’ are left. 

Removing basal branching (legging up) to reveal the culm reveals the wonderful strong soaring culms.

If culms are leaning excessively prune as follows:  Retain lowest set of branches; remove the next two sets of branches; retain the next set of branches.  Note the bottom and upper set of branches are opposite; symmetry is maintained.  Repeat this pruning process all the way up the culm.  The result is an airy canopy with an increased vertical axis.

• Screens and hedges  Remove culms too tall (Phyllostachys aurea), or prune off the top with shears after the shooting season is completed (Shibataea kumasaca).

• Low spreading ground covers  Cut to ground around Valentine’s Day (mid February) to promote fresh vibrant new growth if foliage is looking ragged.  Mid summer trimming with hedging shears to maintain height may also be desirable (Pleioblastus distichus).

• Clumping bamboos:  Once established, older and weak culms often become floppy due to mass of foliage. Thinning these out after shooting also reveals the subtle beauty of the newer culms, but this pruning is not essential for the health of the plant.

 

• Pruning neglected clumpers and timber bamboos:  If the stand is too dense to gain access to cut out a wedge shape from an unseen part of the stand before thinning.

 

In cities, spreading bamboo can move freely from one garden to another and require maintenance to avoid their becoming thugs.   If the care for spreading bamboo seems too much work after reading this handout, either feel free to contact us or consider clumping bamboos instead, which only increase in diameter a few inches per year, making them not only more drought tolerant but lower maintenance.

 

Avoid using submerged pots, bath tubs, or bins, underground concrete walls, sheets of metal or fibre glass; they all fail for various reasons.  Concrete driveways, even double driveways, asphalt paths and driveways, or lawns do not stop the spreading bamboo.  Only gravel driveways that are very dry in the growing season and are driven over regularly act as an effective barrier.  Knocking down rogue shoots popping up in shrubberies or lawns merely removes the evidence of the bamboo, but the rhizome (underground stems) remains.  So, if your bamboo has got out of control all of the rhizomes will need removing back to the parent plants desired site.  Herbicide is also very ineffective and of more danger to wildlife and us than the bamboo!  Clearly, effective maintenance rather than neglect is the only viable strategy for this beautiful if roguish, grass.  A well tended bamboo can require less time than maintain roses (less thorny too!)

 

Realistically, only high density plastic barriers, rhizome traps, or a combination of both will work.

 

(30 inches tall and 60 mil. thick) are ideal for perimeters of properties.  Some people use 80 mil. thick barriers, but we have no experience with them.

 

Mark out and measure the perimeter of the site using garden hose pipes or rope.  Consider organic flowing shapes reflecting the free spirit of the bamboo.  Avoid corners and sharp curves, as this can cause too much pressure on the barrier.

• Allow 6 inches to 1 foot space between a fence or perimeter to allow access for future maintenance.

• Dig a trench 28 inches deep by 1 foot wide, keeping the soft top soil separate from the heavy clay.  Remove all sharp objects (sharp stones, glass, metal, etc.) from the soil.

• Place the barrier into the completed trench and temporarily hold into position with 3 feet tall sticks or rods.

• Leave two or three inches of the barrier sticking up above the ground to prevent the rhizomes from escaping over the top undetected.

• The barrier needs to be secured where the ends overlap to prevent the rhizomes from escaping. A good securing strip are stainless steel clamps measuring 1 inch by 28 inches.  Do not leave the clamps sticking above ground level, as this could be hazardous.

• Backfill the trench with the clay first compacting it hard as you go.  Next, add the top soil to within 1 foot of the soil surface.  Lastly, add hemlock mulch which will make checking for rhizomes much easier.

Essentially, this plastic sheet of barrier is a bottomless pot submerged in the ground with the rim left above soil level.  Rhizomes exist in the top surface to a depth of 1 foot.  Heavy clay discourages rhizomes from going deeper and escaping under the barrier.  So, never amend the soil below the top foot. If the site is less than 4 feet wide avoid fully enclosing the bamboo with barrier; it is very awkward to rhizome prune as required.  Finally, these barriers cannot be used with sandy soils.

 

Even this strong plastic can fail under the pressure of rhizomes.  To avoid this, in June, August and November remove all rhizomes from within 6 inches of the edge of the material using a “sawzall” (reciprocating saw) and pry bar.  Take care not to damage the plastic.  Remember, new growth removed regularly is far easier than rhizomes left for several years, so be consistent with rhizome care.

 

• This is a trench (one foot wide by one foot deep) backfilled with light material such as hemlock mulch or sand.

• Rhizome traps do not prevent the spread of the rhizomes, rather it facilitates ease of access for rhizome pruning.

• This method encourages a more natural open stand to develop; is by far easier to manage; avoids having to dig deep trenches; and saves on the expense of the barrier and clamps.

• Avoid this method when planting spreading bamboos on the edge of your property.

 

• As with plastic rhizome barriers, the rhizome trap will need checking for tender new rhizomes in June, August and again in November each year.

• All unwanted rhizomes will need removing. 

 

The following takes the best advantages of both the plastic barrier and rhizome trap.  We prefer this by far for screens planted on the perimeter of the garden.

• Always install the barrier 6 inches to one foot away from the edge of the property allowing the ends of the material to curve back toward your garden, thereby redirecting the rhizomes.

• Install the rhizome trap around the remaining boundary of the bamboo.

 

Clumping bamboo stands or screens only increase in girth by a few inches a year, and hence, there is no concern about unwanted spread.