OKAMI GARDENS BONSAI


DEVELOPING BLACK PINES FROM SEEDLINGS
By Brian Gershuny

Continued from: ‘Growing Seedlings For Bonsai’.

Contents


Still year 1:
It is now fall and the pine seedlings have been in their 6" pots for one growing season.  This has primarily been a recovery period.  A shallow root system is starting to develop.  The top growth will be mush less than normal Christmas tree seedlings because of the sever initial root pruning.

Pine seedling have a lot of variability.  Some will be very short and others will be long and scraggly with needles only at the top.  They will all be useful.  As the seedlings develop you will divide them up into small, medium and large trees.  Seedlings come in bundles of 50 or more so you will have plenty of opportunity for different sizes and styles.

A little about pines.  Pines are more complicated to grow than deciduous trees.  Pines have certain types of growth at different times of the year.  You can only push their growth so far.  The different training techniques are more time dependent.  Because of this, they require more planning.

The dates that I give in this article are for the southern New Jersey area, Zone 7.  Please adjust your dates accordingly.

Some points to remember about pines:
Pines have growth two spurts each year.  In late spring last years buds will grow into what we call candles and harden off by July.  At the same time dormant buds that are activated by sunlight grow short shoots.  The second flush of growth starts in late August.  There is more thickening than lengthening during this growth period.  At the end of this growth period in late September, the growth lignifies (becomes woody) for the winter.  Food, in the form of starch, is stored in the roots.  Older needles yellow and fall off.  New buds develop now to prepare for next spring.  If the roots are pruned or damaged during the winter, the stored food is not available to the tree in spring and the tree is weakened.

You can prune pines all year.  I prefer to do major cuts during late summer just before the second growth spurt.  The advantage of pruning during the winter dormant period is that it capitalizes on the fall thickening growth.  Black pines will not bud back on old wood.  You can prune to a branch with healthy needles and, with good conditions, it should bud back from the base of the needles.  Pruning in late summer or early spring activates the latent buds by eliminating the growth inhibiting hormone produced in the terminal bud.

Pines are also less hardy in transplanting.  Roots take a long time to recover and are more sensitive to exposure.  You never want to bare root an older pine.  You can get away with it with seedlings.  Pines take a year or two to recover from transplanting, depending on its age and the amount of root damage.  Because of the need to develop a good root system by root pruning and correcting faults, it takes much longer to grow pines than deciduous trees.

General requirements for pines are sun and drainage.  Pines need full sun to stimulate budding.  The sun promotes heavy, short growth and stimulates back budding.  I prefer to give my pines in winter storage as much sun as possible.

Pines are prone to root rot.  Good drainage is a must.  The soil used is coarser than  the soil used for deciduous trees.  Some growers plant their seedlings in plastic colanders to facilitate good drainage.  Avoid clay soils in the field.  Add the proper amendments to provide drainage.  The type of fertilizer you use seems to make little difference.  I have used all types over the years.  All have advantages and disadvantages.  I have no preference.  Applied correctly, they are all good.
 

Training pots under benches. 

Pines and maples mulched for winter.

Maples being mulched with mowed leaves.

Winter care for the pine seedlings is pretty straight forward.  There is no pruning in the first year.  I just push all the pots together and push mulch, or leaves that I have run through a mower, against the outside.  I try to pick an area that is somewhat sheltered from the wind but gets a maximum of sunlight.  Wind causes more damage than cold.  Being pines can be worked during the winter, keep those you plan to work on near the edge so you can reach it.

Year 2:
Cut back the seedlings to 3-5 inches in late march.  This forces side branches that will thicken the trunk.  Be sure there are healthy needles on the section that remains.  Make the cut at a 45 degree angle with sharp scissors or concave pruners.  If there are a lot of long needles on the stem, cut the needles in half to let light in.  Seedlings that are long and scraggly with no lower buds will be treated differently.  Just put them aside.
 

Typical seedling after 1 year.

Cut top leaving buds. 
Note angled cut.

Wire applied.

Twist trunk.

The next step is to wire the seedlings.  The purpose of this is twofold.  The first, obviously, is to give some shape to the trunk.  However, you will keep this wire on until it cuts deeply into the tree. The cutting causes rapid thickening of the trunk. Be sure the bark does not grow over the wire.  There will be enough growth later so you will not be able to see marks from the wire. (Note: do not try this with most deciduous trees.)

I use 3mm aluminum wire that I get from an electrical supply.  It comes as 1" cable.  It is silver colored, not copper, as is usually used for bonsai.  There are two advantages to this.  First, it is cheaper.  Second, It is easy to see making it a good reminder to remove it.  (I use a lot of this on my field trees.)

The best way to wire is to put the end of the wire in the soil and rotate the pot.  Be careful not to wire over the buds or flatten the needles.  Wind some clockwise and some counterclockwise.  Twist and bend the seedling in the direction of the windings.  Leave some straight and some just angled.  Wire the scraggly seedlings and bend them into unusual shapes.  They will make interesting bunjin.  Think of the twisted shaped trees in the old Chinese paintings.  Remove the wire when it cuts into the tree by unwinding it.  It will leave an ugly scar that will heal over within 2 years.

Place the pots in a sunny area about 1 foot apart.  Fertilize heavily throughout the year and keep well watered.  6" pots dry up very quickly.  There will be no pruning this year.  By the end of year the trees should look like bushy little Mugo pines.  Treat them for winter the same as you did last year.

Year 3:
Transplant the seedlings into 10" bulb pans in April.  Bulb pans are 5" deep and make great training pots.  They are available from many garden supply houses.  3 gallon pots can also be used but I prefer not to have the extra depth.  They also use more soil making them less cost efficient.

The soil is a mix of coarse sand (about 1/8" diameter), coarse perlite and commercial nursery mix in a ratio of 2:2:1.  For sand I use a turkey grit in a medium (grower) size.  Oil Dry or certain clay based, non-clumping cat litters also work fine.  The mixture must be very porous.

Spread the roots out when you transplant.  Much of the soil will fall of but do not help it to do so.  Correct any faults now.  Be especially alert for roots that wrap around the trunk.  Keep root pruning to a minimum.  Dust the roots with rooting hormone powder such as Rootone.  Plant at the same level as it was in the smaller pot.  Use a chopstick to eliminate air pockets.  Soak each pot for several minutes in a tub of water with Superthrive and Bioplex in it.  Place out in the growing area two feet apart.

Again, fertilize heavily and keep well watered.  Let the trees recover and grow.  Just before you put the trees away for the winter, cut the top shoot back to the lowest branch on that stem.  Push the pots together and mulch.

Year 4:
This is an easy spring.  Just put out the trees two feet apart, fertilize and water until June.  The branch you left after pruning the top last winter is the new apex (for now).  Other branches should also be growing from that node. Leave the top to grow out.  Leave all the side branches to grow.  The cuts on top should start giving some shape to the trunk.  Start to look for an interesting trunk line.  In some trees it will be obvious, others, not for a few years.

In August you will need to make some big decisions.  The trees will be very different looking although they are the same age.  You have to decide which trees will be small, medium and large Bonsai.  Your decision should be based on the trunk line, the spacing of usable branches and the roots.

Small Bonsai will be easiest to spot.  They will look like a normal pre-bonsai waiting to get wired and planted into a Bonsai pot.  Mark the front of the tree with a nail in the soil.  Prune off any thickening branches in the front now.  Before you put the pines away for the winter, cut back any long branches to the first secondary branch from the trunk.  Shorten the secondary branches as well.  This reduces energy flow to those branches, strengthening the other branches you will use in you final design.  It also allows the pots to be pushed closer together in the winter.  It will stay in this pot for another year yet.  Trim out some of the needles that are 2 or more years old.  (to Small Pine Development.)

Medium Bonsai (about 8-16") will be planted into a 5 gallon squat container.  This is about 13" wide and 10" deep.  A 7 gallon pot will do but, again, soil costs are prohibitive and unnecessary.  Some growers use crushed stone (like on a driveway) in the bottom of the pot to take up space.

Use the same soil that you used for the last transplanting.  Do not disturb the roots at all. Plant at the same level.  Water well.  Fill in ant soil that may have settled and mark the front with a nail in the soil.  Push the pots together and mulch for the winter.  (to Medium Pine Development.)

Large Bonsai do not have much shape at this point.  So far only the base and shallow root structure are developed.  These will be planted in the ground.  Preparations should be made in early summer for planting in late August or early September.  (to Large Pine Development.)

Choose a site with full sun.  It should also have access to water.  As mentioned before, the soil needs to be very well drained. Add sand and organic matter  to soils with a high clay content.  Plant the trees 4-5 feet apart.  Leave room for a mower to run in both directions.  Keep the root ball intact.  There is no root pruning or correcting now.

From this point on I will discuss the rest of the development of the three sizes of pines.  Keep in mind there are many different tasks to perform at particular times of the year.  You will need to plan ahead in order to get all the jobs done.  The finished product will be well worth the effort.


Large Pines - Yr. 5:
Because the root ball was not disturbed there will be minimal recovery time.  Fertilize heavily this year.  Pinch back candles in mid June.  3-5 new shoots will grow back.  Select out 2-3 shoots in August.  Leave the others to grow out for the rest of the year.  In early winter (around late November) trim the new shoots to 2-3 inches.  Prune off any thickening branches over 1" thick.  Use shoots at the top to change the direction of the trunk line.

This procedure is repeated for four years.  Each year the growth is stronger.  Continue forming an interesting trunk line.  Be sure to keep an eye out for branches to use in the final design.  Try to keep thickening branches at different levels so as not to form a knot on the trunk.  Use wire on your developing branches to get a good angle on the trunk.  Wrap the wire around the branches or pull the branches down with guy wires.

In the third year of the tree being in the ground, you will need to root prune.  I do this in two steps.  In spring, prune the left and right side.  In early fall, prune the front and back.  Cut down with a sharp spade at a 45 degree angle under the tree.  You do not need to prune every root.  Try to get most of them, especially the thick ones.  Some will be cut again next year when you dig it up.

Depending on how the tree is growing (and how busy I am) I sometimes wait until the fourth year to root prune.  I can transplant in the next spring or in early fall.  The reason for transplanting is to eliminate the downward growing roots that will take over and ruin the tree.  It is also a chance to correct any faults in the roots.

Dig the tree, root prune and make corrections quickly to minimize exposure to the air.  Disturb the roots as little as possible.  Avoid doing this on a windy or hot day.  Keep the roots moist (not wet)  Loosen the soil in the hole and add whatever amendments are needed.  I always use a barrier such as a concrete patio tile or an 18" square of exterior plywood in the bottom of the hole.  A more detailed description is given in my article, Developing Maples From Seedlings, in the section on barriers.

Continue pinching pruning and wiring as you have been for the next four years or until your tree is ready for a bonsai pot.  Slowly eliminate the thickening branches.  Develop an apex from a side branch.  When the tree is almost the size you want, begin pinching candles in July so that secondary growth is shorter.  Develop the tree just as you would any bonsai.  Cut off the old needles to force buds further back.  Prune back branches to develop a refined structure.

Dig the pine in the spring.  Have a bonsai pot ready.  You should have a good idea of the root structure being you dug the tree up a few years ago.  Don’t forget about the barrier.  There is no feeling like slamming a shovel into concrete on a cold day!  Make your final root corrections and remove any heavy soil under the tree.

The tree will be in this pot for four or five years so be sure it is appropriate for the tree.  Take great care in setting the roots and wiring the tree down.  Use a coarse Bonsai soil mix for pines.  Give the pot a good soaking in a Superthrive and Bioplex solution.  I keep the trees in a cold greenhouse until May.  Protect the tree from the wind.

You will see very little growth in the first year.  I would recommend waiting until the first winter before wiring and pruning. I give my trees a year of rest before continuing training. I soak the trees a few more times during the year in the Superthrive and Bioplex solution.  Pinch the candles in late June. After the first year the trees are very well established and all the standard training practices can be applied to them.


Medium Pines - Yr. 5:
Medium trees are trained almost the same wayas trees in the ground.  Continue to develop movement in the trunk.  Pinch the candles of branches to be used in the final design in June.  Choose 2 or 3  new shoots and trim back to 1-2 inches in August.  Cut off any thickening branches greater than 3/4" in diameter.  Cut off any in front, too.  As in large trees, leave the top grow out.  Do not pinch candles or prune these.

Continue the annual pinching in June and cutting back in August until the tree is almost the size you want.  Cut the top thickening branch off when it is 1/2 to 3/4 inches thick.  Another shoot can be left to grow out near the apex to continue thickening the trunk.

Wire down branches you will use in the final design while they are still relatively thin.  Be sure to work buds close to the trunk.  Do not start with buds near the outside of the final design and hope to thicken the foliage behind it with back budding.  Use the outer part of the branch to thicken the base.  Prune it back when the part you want to keep is almost in scale with the trunk.

At about the third year in the 5 gallon pot, the tree should be at the height you want.  Let the candles grow out until early July.  Pinch them back at this time.  Trim off the extra shoots in August leaving 2 or 3.  There will be no need to trim these. Remove the top thickening branch.  Cut off about 1/3 of the remaining thickening branches.  In early winter (December), cut off the remaining thickening branches.  Cut off all the needles older than 1 year with sharp scissors.  Leave about 1/16" remaining.  This is to prevent injuring any latent buds.  Leave all of this years needles.  As always mulch the pots in a wind protected area.

The tree can be transplanted into a Bonsai pot in late April or early May.  It will be in this pot for the next 3-5 years.  Use a coarse Bonsai soil mix and
give it a good soaking in a Superthrive and Bioplex solution.  The trees will recover much quicker than field grown trees.  If growth is strong, pinch the strong candles in late June.  Do not wire now.  If the growth is not strong just let the tree grow.  Be  careful not to burn the roots with fertilizer.  I find the liquid types used at 1/2 strength every week work well.

Trim back the shoots in the winter.  Trim off the old needles and wire.  If the secondary shoots were strong they can be thinned to 5-9 bundles.  Protect the trees in winter as you would any Bonsai.  In spring you can resume the normal training regime for pines.


Small Pines - Yr. 5:
At this point small bonsai are still in the bulb pans and look like regular Bonsai trees with extra spindly branches.  These trees are essentially Pre-bonsai ready to style.  You just will not be transplanting them, yet.  The training can begin during the winter.

Take your time studying the tree as you would in any Bonsai.  Leave the thickening branches for now.  Prune back the branches used for the final design.  Cut back to usable shoots.  Do not worry about the final outline of the tree right now.  You can always grow the branches out.  It is difficult (if not impossible) to thicken inwards.  Wire the tree and put it back in its protected area.

Let the tree grow through the spring.  Pinch the candles on the final branches in early July.  Leave the thickening branches and the top to grow.  Prune out the secondary growth in August leaving 2 shoots per branch (3 near the apex).  In early winter pull or trim off the old needles and thin this year’s to five bundles.  Cut off all the thickening branches.  Mulch them in for the winter.  In spring they are ready for wire and their final bonsai pot.  The roots will be very strong and they can be trained like any pine bonsai.


Some Notes:
Roots will grow out of the nursery pots.  You will probably notice them when you try to move the pots to their overwintering area.  They help the trees grow faster during the year.  I just pull them up but do not cut them off now.  Food is already stored there.  I prune them off in the late spring when I put them out in the growing areas again.  Like any root pruning, it stimulates finer roots closer to the trunk.

As I said before, other conifers can be grown using this method with some modifications.  Some trees such as spruce and yew bud back well.  Others, like white pine, do not.  Do not let the branches of these get ahead of you.

The basic principle is to get a lot of buds on the initial seedling and grow those low branches out to thicken the trunk.  Remember, also, that as a tree grows the bends you put in to the trunk seem to straighten out.  Trees thicken more on the inside of curves.

Also keep in mind that 50 seedlings are not a lot of work.  50 pine Bonsai are!  Pace yourself and cull fearlessly.  Most Bonsai enthusiasts would rather have several magnificent specimens than a yard full of mediocre ones.

There is a lot written here.  It covers many years of training.  Pines can not be rushed.  There is no substitute for time.  Check the Links Page if you have trouble getting the supplies.  Hopefully, this article will be useful to you.  I hope to see some of the results on the Internet some day.

Good Growing!


Copyright 2000 Brian Gershuny.  All rights reserved.

2/00 B.G.