OVERVIEW
Pinus is a genus of approximately 120 species of monoecious, evergreen, coniferous trees or shrubs, widely distributed throughout the world particularly occurring in mountainous and arid conditions where they are able to thrive.

Pines are a classic bonsai species in Japan and the world over, they are not however, easy trees to care for and style without experience. Pines have their own growth patterns that differ greatly from deciduous and common coniferous species; these growth patterns need to be understood before successful styling and pruning can be carried out.
As can be seen in the accompanying pictures; pines are not only used for bonsai in Japan, they are also very often seen cloud-pruned in Japanese gardens.
Pine foliage is in the form of needles that are most commonly formed in bundles of two's and five's. Some pine species have long and/or curved needles that make them difficult to style effectively as bonsai, however Pinus species that display short needles are nearly always suitable.

There are large numbers of pine species suitable for bonsai though for the purposes of this article I will outline the four most frequently used for bonsai;

A conical or columnar tree, often with a spreading crown native to Japan. 2-6cm long leaves are a deep-green colour with whitish blue inner sides, giving rise to the name, the White Pine. White pines are frequently grafted onto the more vigorous Black pine/ Pinus thunbergii rootstock to improve vigour and growth-rate.

Japanese White Pine/P. parviflora Pruning and Care Guidelines

BONSAI CULTIVATION NOTES

POSITION Give pines as much sunlight as possible during Spring, Summer and Autumn. Insufficient sunlight will result in extended needle length and dieback of shaded branches. Though very hardy in Winter, Pines should be protected from freezing winds when their roots are frozen.

WATERING All Pines dislike permanently wet soil though care should be taken to ensure their soil never dries out completely. It is important that a very fast-draining soil-medium is always used. Pines also benefit from regular misting.
It is often recommended that Pines are given minimal water during the Spring to reduce needle-length, as is discussed in an article on pruning pines elsewhere at Bonsai4me.com, my personal feeling is that the withdrawal of water is an unnecessary risk to the health of the tree.

FEEDING The normal recommendation for feeding pines is to feed with a low-nitrogen fertiliser once in Spring and then to withdraw all feed until new needles have hardened off in late-Spring. The idea being that by 'starving' the tree, needle length will be reduced. The tree is then fed a high-nitrogen feed every 2-3 weeks until early-Autumn.
My personal view is that withdrawing feed is unnecessary as following the correct pruning technique as outlined elsewhere at Bonsai4me.com, can reduce needle length. By correctly pruning, Pines can be fed with a balanced feed throughout the year, resulting in strong vigorous growth, and still retain reduced needle length.
Pines benefit from an occasional replacement feed with Miracid, two or three times a year.

PRUNING Pruning Pines Pinus mugo/Mugo Pine Indepth Japanese White Pine/P. parviflora Pruning and Care Guidelines
When styling, be wary of reducing a nursery Pine's top growth by more than 50% in one vegetative period. Reduce the height of the trunk (and foliage) slowly.

The general rule with mature (over 30-40 years) Pines is to keep to 'only one insult per vegetative period'. After repotting, drastic pruning, wiring or styling you must then wait until 12 months elapses before carrying out any further work. This also means that if a Pine is styled in the Summer, it cannot be repotted the following Spring.

Immature, young pines will take more work than this each year without weakening but it must be remembered that Pines should always been developed slowly.

Trunk chopping and heavy branch pruning; carry out in Autumn when the sap flow in the tree is slower and sap loss will be reduced. Prune back the branch or trunk leaving a short stump. Seal the wound with Vaseline/petroleum jelly, this will seal the wound well, stop sap bleeding and not leave a hardened congealed mess at the wound-site. Allow the stump to dry out over the following year before either jinning it or removing the stump.

REPOTTING Repot in mid Spring every two to five years, depending on root-development.

Repot as the Pine comes into active growth (the candles have extended and the new needles can be seen held tight against the candle), do not repot too early. Mugo pines react far better to Summer repotting.

Use a very free-draining soil-mix. When repotting, pine soils will often be seen to contain a white, thread-like fungus called Micorrhiza, which are very beneficial to the health of the tree.

When repotting, retain a small quantity of the old compost to ensure that Micorrhiza is retained in the new soil mix. For the same reason, do not wash the roots. Remove old, compacted soil by hand.

It is not necessary to prune any of the foliage of the pine after rootpruning to 'balance' the tree. The waxy needles of a Pine require relatively little moisture uptake from the roots and there is no need to try and reduce transpiration through the above-ground growth. The more foliage the tree has after root pruning, the more strength it will have to repair and regenerate the rootball. The tree will 'balance' the roots and foliage itself.

PROPAGATION Sow seed of species outside in early Spring, the seed needs to be exposed to frosts to germinate. If the seed is fresh, germination can be rapid.
Cultivars need to be propagated by grafting in late Winter.

PESTS AND DISEASES Aphids, sawfly larvae, and various needle cast diseases. Some 5-needle pines are susceptible to white pine needle rust.

STYLING Suitable for all forms except broom.