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Ponderosa pine (Pinus ponderosa)

Ponderosa, also known as western yellow, western red, sierra brown bark, big, black jack or bull pine, is the most widely distributed American pine.  It is found in some one million square miles of the mountain forest of western North America, from British Columbia, east to South Dakota and south to Texas and Mexico.  One of the principal pines in the Rocky Mountain region, it is easily distinguished from all other native conifers as its dark yellowish-green needles, sometimes with a slight silver cast and lasting for 3 years, are 3 to 7 inches or more long and in clusters (fascicles) of 2 or 3.  Ponderosa is found on mountain slopes, on high mesas, and in dry valleys.  It is tolerant of drought and wind and can grow in poor, gravel soil.  Although it has been found as low as 350' elevation in California and as high as 9,800' in Utah, it generally prefers elevations of around 5500 to 8500' in Colorado.  It grows to 150 to 200' high with bases of 4 to 6 feet in diameter.  Its life span is typically 350 to 500 years, with the oldest recorded tree at 1,047 years.  When young the bark is grey-black and is therefore often called 'Black Jack' pine.  When older (around 400+ years) the bark gets yellowish to rusty orange and occurs in thick plates.

It is an ideal material for bonsai culture with rugged bark texture, good natural taper of the trunk, transplants well to most locations, is drought-resistant, and has needles that can be reduced to about an inch or two with basic horticultural practices.  Collecting from the wild has been the principal method of acquiring specimens for bonsai culture in the region -- a way to get fabulous trunks but sometimes weak rootage.  Seedlings, however, can be started for bonsai and they develop beautifully at a good rate in a container or on a rock slab.  No matter what its providence, it absolutely requires as much full sunlight as possible, good air circulation, and low humidity.  Do not mist the foliage or fungal problems may develop.

Ponderosa Pine is relatively easy to train into bonsai because of its flexible branches and growth habits.  It adjusts well to container culture by putting on a lot more foliage than in its wild state.  (It is recommended to collect your first trees with an experienced collector who has done it before.  There is no need to learn by trial and error, inexperience or haste.  The more difficult an individual tree is to collect, the less likely it is to survive.  Ponderosas collected successfully are usually growing on a flat sheet of rock and have a thin and compact root mass which holds together.  Only branches that are much too long should be cut off.)

After collecting a specimen, grow it in a box or pot for two or three years with a soil mixture of over 50% decomposed granite, 25-30% Canadian peat moss, and 20-25% soil from the original growing site.  The original soil contains very important mycorrhizae -- the symbiotic fungi, present in 80% of all species, which colonize the roots of a plant either intracellularly or extracellularly and dramatically increase the mineral absorption capabilities of the plant's roots without the presence of disease-symptoms.  Bare-rooting -- especially an older pine -- can kill the plant.  Try not to do too much root pruning, especially on older trees.

This first container should be large enough to hold the often strangely-shaped roots, but not too much larger or deeper.  Other recommended mixes are 50% crushed granite + 50% Turface or Haydite; 100% crushed granite; 100% Turface; or 50% Turface + 50% pea gravel.  It is recommended to treat newly collected trees as if they were rooted cuttings.  If you do have lots of roots in close-packed soil, poke numerous holes (as if aerating your lawn) in the soil and backfill with a coarse granular soil.  Although they need very little water, if planted in a very coarse, well-draining soil they can be watered freely.  No soil particles should be smaller than a grain of rice.  Ponderosa will send out many new roots under these conditions, and it is a good way to develop the root system after transplanting.  Unfortunately, if water is given freely to promote the roots, the needles will be quite long (6" or longer and possibly yellowish).  But this excessive growth can be restrained in future years by watering less.  Because of this need for the roots to dry out, it is dangerous to overpot a Ponderosa.  Yes, it is safer to keep one of these pines in too small a pot or not give it enough water.  However, in the summer the roots do need to be kept cool, so water more for the evaporative effect than for keeping the Ponderosa watered and be sure to mulch the surface of the pot.  Have the pot then either sit on mulch or on a wood surface.

When growing long-needle pines [such as the Ponderosa, Japanese red, Japanese black, Pitch, and Virginia], the grower is working toward artistic refinement through the technical aspects of reducing needle growth.  Compact design must be carried out in both spring and fall.  The total overall purpose is to bring all branches -- primary / growing out-of-the-trunk as well as secondary -- to middle-size.

To encourage dense branches and short needle foliage, in the spring let the candles elongate to at least one inch or more and then break them off at the base.  In fact, all of the candle can be removed and within a month new candles will appear.  These should be allowed to mature.  They will be shorter and needles smaller.  Many new buds will appear within the interior sections of the branches.

The correct candle-pruning schedule is this:  After about the middle of May, selective candle removal is used on all the larger and stronger branches.  Next, during the last week of May needles are thinned, mainly on the underneath pairs (or triplets if present) to train branches into horizontal planes.  Thin out the needles so only 4 or 5 bunches remain on each branch.  Weak branches are NEITHER thinned nor candle-pruned so they can have a growth advantage.  Then in the first week in June selective candle removal is used on all middle-sized branches.  By October many newly formed buds can be observed on middle and larger branches with buds about the same size.

In the fall, after the needles have matured, needle-cutting should be practiced to encourage dense budding within the interior.  Only the old needles that are one or two years old should be cut to one-half or one-third in size.  This procedure will open the branch to sunshine to promote new buds.  In two or three weeks those old needles will brown and fall off.  New buds will appear in the axil where they were attached to the branch.  Do not pull them off because you will damage the dormant buds.  (It is very normal for the oldest needles to turn brownish-yellow and start falling off in October and November.)  If these practices are to be successful, the bonsai should be fertilized but not heavily only from mid-summer to late fall with a weak solution of slightly acidic fertilizer every week to stimulate future growth.  (Ponderosa tend to grow longer needles when they are grown as bonsai due to better soil conditions and regular fertilizing.)

The following year, after the middle of May remove candles on all large and middle-sized branches.  Then in late May thin needles, mainly on the underneath pairs, again.  Weak branches are still not thinned.

Pruning can be done at any time of year.  Ponderosa has a very resinous and sticky sap that will mar the bark if it is allowed to drip on it.  Either use cut paste to seal the wound or prune the branch leaving a stub.  The stub can be removed at a later date when it will heal more easily without bleeding so much, or simply turn into a deadwood jin.  Because Ponderosa are not as vigorous growers and have a relatively shorter growing season than other pines, do NOT do major pruning more than once a year.

Younger branches are very flexible and can be easily wired into contorted shapes.  Wiring can be done at any time during the year.  Scarring is not a concern as these trees grow slowly and wire can be left on for several years.  The bark is soft and spongy and will bounce back if wire is removed prematurely.  To bend a large branch, especially one-and-a-half to two inches in size, plan where you want the bend first.  Then firmly grip the branch in question with two hands, and twist it as if you are untwisting a piece of braided rope.  At first there is a considerable amount of resistance in the branch, but then suddenly you can feel it 'give' and it will twist much easier after that.  Sometimes you might need to continue working the branch back and forth a bit to expand this newly created soft area.  Then wrap the length of the bend with raffia, wire it once, and make the bend.  (This method, devised by Harold Sasaki, separates the tightly-bound vascular bundle fibers that make up the wood of the tree, but does not disrupt the flow of water from roots to the top.)  Since even heavy copper wire is often not strong enough to hold a large branch in place, use guy wires to hold the bends where you want them.  Soaking the bark in water before wiring is also said to help tremendously.  Wrapping a wet towel around a dead branch overnight very often allows the bark to be easily peeled off the next day.  As collected trees often have a great deal of smaller deadwood branches, you need to be careful not to break off desirable ones while wiring living branches.

As they are used to growing in minimal amounts of soil, repotting Ponderosa is not critical.  Every two to five years is adequate and can be done in April or September.  These trees are extremely winter hardy.  Many growers provide no protection.  The roots normally see very low temperatures in winter (withstanding -30 to -40F), so they are quite tolerant of temperatures that may kill the roots of other species.  In cold regions, simply mulching the pot will be sufficient.  Ponderosa normally have a fairly long period of dormancy, so their chilling requirements are fairly high.  Since the soil normally drains well, be sure to keep them watered in winter to prevent them from drying out.

Material derived from:
Arvin, Daniel  "Ponderosa Pine as Bonsai, Parts One and Two," Bonsai Journal, ABS, Vol. 33, Nos. 2 and 3, Summer and Fall 1999, pp. 68-73 and 109-113;  Kataoka, Robert and Malcolm Correll  "Pine Pruning for More Branches and Shorter Needles," International Bonsai, 1984/No. 4, pp. 14-16; Sasaki, Harold  "Ponderosa Pine," Bonsai, BCI, Vol. XXV, No. 2, March/April 1986, pg. 19; Smith, Andrew  "Making it Bend," Bonsai Journal, ABS, Vol. 36, No. 1, Spring 2002, pp. 19-21; Stowell, Jerald P.  "Some Thoughts On Refining Pine Bonsai," International Bonsai, 1982/No. 4, pg. 17; and Walsh, Andrew  "Species Care Guide -- Ponderosa Pine," Bonsai Journal, ABS, Vol. 33, No. 2, Summer 1999, pp. 51-55.  Additional comments by Pikes Peak Bonsai Society's Bill Fox and David Conlin.

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Thoughts by Ryan Neil, per Capital Bonsai Blog, Sept. 30, 2012

"Ponderosa Pine is known to be Ryan's favorite species for bonsai...

"According to Ryan, in order to get back budding never bud/candle prune Ponderosa.  Also do not remove any needles except those on the bottom of branches.  The reason for this is that the more photosynthetic surface area the tree has the more energy it can invest in creating more buds.  If Ponderosa are treated like Japanese Black Pine they will eventually weaken and die.

"Ryan uses a 1:1:1: mix of Akadama, Lava, and Pumice for his Ponderosa.  [Could] lava or pumice be substituted for something like granite?  He said that the porous nature of lava and pumice provides more pore space for water and air near the roots.  Old collected Ponderosa [that have been potted for several years] only need to be repotted every 15 years so long as you use a hard baked Akadama."

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Collecting Ponderosa Pine,

Repotting Ponderosa Pine at the Bonsai Museum,

and Ponderosa Pines as Bonsai by Larry Jackel (Rocky Mountain Bonsai Society), 2008.
Available through

                           © 2009  Pikes Peak Bonsai Society