Dwarf Mugo Pine Bonsai Care Guide
Pinus mugo is a native of the mountainous regions of central and southern Europe, hence the nickname Mountain Pine. This slow-growing evergreen can be a good choice for beginning bonsai artists. In nature it may grow to 10 feet tall and nearly as wide.
The Dwarf Mugo has grayish-brown scaled bark and bright dark green needles of about 1-1 1/2". The shape may be pyramidal or round, with dense needling, as the needles remain on the tree for four years.
Like most conifers this bonsai will do best grown outdoors. It is hardy to cold but the roots will need protection from freezing temperatures. Mugo can be kept indoors if given plenty of light and humidity to protect the needles from drying out. This tree prefers full sun, though it can be grown in partial shade as well.
The drought-tolerance of this tree makes it easier for new owners or bonsai enthusiasts who may be away from home for periods of time. It may be permitted to dry out between watering, and quick draining soil should be used to prevent root rot. The roots of the Dwarf Mugo grow closer to the surface than most bonsai so a layer of mulch may be applied to help them stay cool and retain moisture. Misting may also be useful in hot, dry weather or if the tree is kept indoors.
There are a couple of fertilizing options for this evergreen bonsai. You may use a slow-release organic mixture once a month from early spring to late fall, or feed bi-weekly with a fertilizer made for acid-loving plants. Some bonsai enthusiasts recommend refraining from fertilizing throughout the hottest two months of the summer, as well as if the tree is sick or was repotted in the previous two to four weeks.
Common Styles – these trees are easiest to shape in their natural form. They can also be coaxed into a slant and sometimes even a windswept.
The first pruning of Pinus mugo should take place during the first repotting. After that pruning may be performed in the fall, while wiring the tree. In the spring the candles should be pinched by two thirds, before they open. Pinch the heartier candles first, then wait a week and pinch the weaker ones.
In fall, pinch off needles that are too long or grow downward. Thin more toward the top of the tree and less as you move down, thus allowing more light to get to the bottom branches and stunting the growth of the apex. Also in the autumn ramification may be stimulated by removing all buds except two on each branch. Wire in fall to late winter, leaving the wire on for no longer than 6-8 months.
The Mugo may be propagated by planting seeds in well-watered soil in the fall, however this is a very time-consuming process.
The Dwarf Mugo should be repotted every two to three years if young, and every three to five years for older trees. Pine bonsai need a deep container with coarse, well-draining soil. The root system should be preserved as much as possible and should not be rinsed. Conifers have a specific organism growing in conjunction with their root system and this fungus is needed for the tree to survive.
Insects/Pests & Diseases:
Although these trees are, overall, pest and disease resistant, they can be affected by certain conditions, especially if not kept healthy.
Mugo Pines may suffer from needle scale. These insects are easiest to kill in the crawler stage, which in many areas of the country is in late spring. Applying insecticide before they develop their white scaly shell gives you the best chance of eradicating them.
Pine sawfly can also be a problem for this bonsai. If not diagnosed quickly they will strip a tree of needles with amazing speed. The eggs are light tan and are laid in a straight line down the needle. Treat with insecticide or neem oil just after the eggs hatch.
This species is particularly vulnerable to diplodia tip blight, a fungus that kills the tips of branches, particularly in older trees. Remove affected areas and treat with fungicide.
Like most pines, this tree is also susceptible to needle cast. This fungus is evident by the appearance of bars of discoloration along the needles and sometimes a swollen black spot on the needle, where the spores have formed. Copper-based treatment can be an effective preventative but chemical fungicide may be needed to cure the plant.
The best bet for any bonsai, including pines, is to keep a close eye on the moisture levels as well as the foliage color and take action at the first sign of an insect infestation or discoloration of leaves or needles.