(Editor's Note: This article was originally published on May 1, 2010. Your comments are welcome, but please be aware that authors of previously published articlces may not be able to respond to your questions.)
Most gardeners are familiar with mugo pines. They are certainly among the top-selling pines in the landscape industry. Their overall small size makes them useful for smaller garden, which are becoming the norm these days. They are used as foundation plants next to homes and buildings, as evergreens for the rock garden, as landscape shrubs for slopes and roadside medians and the list goes on. Few conifers are as versatile as mugo pine. Carefree, they only ask for full sun and a well-drained soil. They do not seem fussy about soil pH although if too alkaline, the plants may go a little yellow. They can tolerate windy sites and salt spray, making them ideal for coastal gardens. They also exhibit considerable drought tolerance. Hardiness is not a problem; they can be grown in zones 2 to 8. Generally they do not require extra fertilizing but if your plants seem a bit too slow (slow is the norm however) you can add an evergreen fertilizer in spring just as the buds start to grow.
Mugo pine (Pinus mugo) also go by the name mountain pine, Swiss mountain pine and dwarf mountain pine. Some books spell the name ‘mugho' but botanically, there is no ‘h' in the name. This pine, as the name suggests, come from high mountains, in this case, the mountains of Europe. These include the Alps, Apennines, Pyrenees, Balkans and Tatras. In the wild, they extend into the subalpine and even alpine zones. Although grown as a dwarf, in their native haunts, they can reach 6 m (20 feet) which is small for a pine but certainly too large for a small city lot. Not to worry, if properly tended to as a young plant you can maintain them as a small-sized conifer for years.
Above are example of mugo pines when they have not been pruned on an annual basis.
Pruning should be done on an annual basis to maintain tight, compact plants. Some very dwarf selections require no pruning, but most do benefit. Pruning is simple due to the unique way pines grow. The new growth of pines elongate first (often called a candle) then produce their needles after the new stems have almost reached their full length. To prune any pine (but especially mugo) wait until the new growth has fully extended but the new needles are only about 1/4 to ½ of their mature length. At this stage, cut back the current season's new growth by half to three-fourths, depending on how severe you want to be. This early pruning will allow the plants to produce a cluster of growth buds at the cut point, resulting in denser growth of branches the next year. If you wait too late to prune, only one bud might form at the cut point, which will not really help thicken up the plant in subsequent years. Never prune back into 2-year-old wood or older, as the plants will not generate any new buds at the cut point.
The main pest of mugo pines are pine sawfly and pine shoot tip moth. Both attack the current seasons growth and can be devastating. Watch plants carefully for the first signs of the larvae and spray the plants with insecticidal soap (on a cloudy day); other appropriate insecticides or even hand remove them. Diplodia tip blight can also occur resulting in the browning and death of the current seasons growth. Prune out the affected parts and burn or dispose of them in the garbage.
'Alpenglow' maintains a tight compact, somewhat flat-topped habit even without annual pruning
Most of the ‘standard' mugo pines sold in the nursery industry are essentially the wild type so annual pruning is a must. The so-called ‘dwarf mugo pine' in the trade may also be just the standard species but if lucky, the tag will say Pinus mugo 'Mops', Pinus mugo var. pumilio or Pinus mugo var. mughus. If so, these selections will stay quite compact even without annual pruning. There are at least 50 named selections of mugo pine which can vary in ultimate size and overall shape. Rarely, some are upright and pyramidal like a typical conifer, albeit, compact in size. 'Big Tuna', 'Aurea Fastigiata', 'Gallica', 'Dolly's Choice' and 'Rigi' are such selections. Others are completely prostrate and flat like 'Corley's Mat', ‘Slavinii' and 'Spaan's Pygmy'. With a more rounded habit are 'Allen', 'Kobold', 'Mops', 'Ophir' and 'Sherwood Compact'. Compact, flat-topped forms include 'Alpenglow', 'Flat Top', 'Kissen' and ‘Sherwood Dwarf'. The smallest selections include 'Humpy', 'March', 'Mitsch Mini', 'Paul's Dwarf', 'Valley Cushion' and 'Teeny'. These latter ones are ideal for bonsai or alpine troughs.
Some of the smaller selections include 'Mitsch Mini' (top left), 'Sherwood Compact' (top right), 'Valley Cushion' (lower left) and 'Teeny' (lower right)
There are no true blue mugo pines but those with distinct blue tint include 'Blue Form', 'Rock Island Compact' and 'Slavinii'. There are several yellow forms. Most of these are greenish in summer, turning yellow in winter and include 'Aurea', 'Aurea Fastigiata', 'Ophir', 'Variegatum Aureum' and 'Winter Gold'. For yellow spring growth that turns green in summer try 'Gold Spire'. Finally there is 'Yellowpoint' whose needles are yellow-tipped all year.
'Rock Island Compact' is reasonably blue in colour while 'Wintergold' glows through the dreary winter months.
There are certainly many other selections not mentioned that are equally attractive and worth investigating, but these few listed above will be at least a starting point in your adventures with mugo pines!
I would like to thank the following people for the use of their pictures: conifers ('Dolly's Choice', 'Mitsch Mini' and 'Rock Island Compact'), palmbob (unpruned P. mugo right) and slyperso1 (unpruned P. mugo left).