How to Grow and Care for Austrian Pine

If you can avoid the serious problems that sometimes afflict the Austrian pine (Pinus nigra), it can be the perfect conifer for a city landscape. It is able to withstand many challenging environmental conditions of an urban environment, such as pollution and salt sprays in the air. It is also quite an attractive pine in the landscape. The tree forms a pyramidal or oval shape while young, and with age, the crown becomes rounded and forms a flat or dome-shaped top. The bark on a mature tree consists of dark brown or gray furrowed plates. Each fascicle has two dark-green needles 2 to 6 inches long, and the brown egg-shaped cones are 2 to 3 inches long.

Like many pine trees, Austrian pines do best if they are planted in fairly warm soil; late summer can be an ideal time to plant an Austrian pine. You can expect this pine to grow at a moderate rate of 12 to 18 inches per year in most circumstances.

Austrian Pine Care

This tree typically grows to 40 to 60 feet tall and 20 to 40 feet wide, so it will need to be given plenty of space in the landscape. In rare cases, Austrian pines can grow over 100 feet tall. Austrian pine has the same cultural needs as most other pine species. It will do well in a sunny location with rich, well-draining soil. Container-grown or ball-and-burlap trees should be planted in a large, carefully prepared hole and backfilled with soil that is amended with peat or another acidifying organic material.

Be aware that this pine has some serious drawbacks for many regions of the country. It is extremely susceptible to the tip blight fungus Sphaeropsis (Diplodia)—so much so that planting the tree is strongly discouraged in many parts of the U.S. Even if you can avoid this serious problem, Austrian pine is prone to a variety of other disease and pest problems. Before planting an Austrian pine, consult your local University Extension Service to learn how well it grows in your region.

Light

This tree grows best in a location that receives full sun, but it can also tolerate a part-shade planting site, provided it gets at least four hours of sun daily.

Soil

The Austrian pine is able to grow in many different types of soil, especially ones that can be considered difficult, such as clay or sand. However, it thrives best in deep, moist soil that drains well. It has a better tolerance for alkaline soil than most pines.

Water

Water new trees regularly for the first year and during dry periods for the first three years. Once established, Austrian pines are fairly drought-tolerant.

Temperature and Humidity

This tree is well suited for USDA zones 4 to 7, hardy down to minus 25 degrees Fahrenheit. This is a species that prefers cool to cold temperate climates; in warmer, more humid climates it will be susceptible to more disease and pest problems.

Fertilizer

Feeding is not required for this tree. A 2- to 3-inch layer of mulch under the canopy will help provide slow-release nutrients and keep the soil moist and cool.

Types of Austrian Pine

There are several good cultivars available for Pinus nigra, including:

• ‘Austriaca’ : This variety has a stout growth habit with a broadly oval crown.
• ‘Pyramidalis’: This cultivar has a more pyramidal shape than the species tree, even as a mature specimen.
• 'Arnold Sentinel': This is an upright, columnar-shaped tree that grows 20 to 24 feet tall, and 6 to 7 feet wide.
• 'Globosa': This is a slow-growing, dwarf variety with a notably round shape. It will take 10 years to mature into a 1- to 5-foot specimen
• 'Hornibrookiana': This is a dwarf shrub variety, just 1 to 2 feet tall, with a spreading, mounding growth habit.
• 'Oregon Green': This 20-foot specimen is prized for the white upright "candles" of new growth that appear in spring.

Pruning Austrian Pine

Little pruning is necessary, other than to remove dead or diseased branches. However, the branches tend to droop as the tree ages, so some pruning may be necessary to raise the canopy where the branches overhang sidewalks, driveways, or other living areas. Late winter or early spring is the best time to do this pruning, as the tree will be less susceptible to invasion by insects or fungi.

This tree's natural growth habit is to produce limbs all the way to ground level, so if you want clearance below the canopy, you'll need to prune away the lower branches—which is best done in later winter or very early spring.

Propagating Austrian Pine

Pinus nigra, like most species in the genus, is difficult to propagate by vegetative means, so it is usually propagated by seed.

How to Grow Austrian Pine From Seed

Austrian pines are propagated by seeds found inside the cones. However, the seeds are slow to germinate and develop into saplings and can take as many as five years to grow in pots before they are suitable for landscape planting. Further, some of the named cultivars do not produce viable seeds, so this method works best for the native species. If you want to try seed propagation, here's a method that works for most pines:

1. In the fall, collect some large cones that are fully brown and still closed. Lay the cone out indoors in an open box to dry.
2. As the cones dry, the scales will open and the seeds inside can be shaken to release them. If the cones are reluctant to dry, you can put them in a warm spot (100 to 110 degrees) until the scales open.
3. Mix the seeds with moist sand, place them in a clear plastic bag, and refrigerate them for three to seven weeks. This cold stratification improves your chances for successful germination.
4. Sow the seeds in small pots, just barely covering the seeds, and set them in a bright location at a temperature of about 60 degrees. This may require placing them in a basement or garage under grow lights. The seeds should sprout within 30 to 60 days; continue to grow them in their small pots until spring.
5. In spring, transplant the seedlings into larger pots filled with peat-based potting mix. and move them outdoors. The seedlings should be at least 2 inches tall before transplanting.
6. Continue to grow the seedlings outdoors in their larger pots until they are large enough to transplant into the landscape. Depending on the variety, this can take several years. Potted trees should be moved to a sheltered location for winter.

Potting and Repotting Austrian Pine

Dwarf cultivars of this slow-growing specimen can be grown in large pots, at least twice as wide and deep as the tree's nursery container. A heavy clay pot is best, as it will resist tipping. Make sure the container has good drainage holes, and use a good-quality peat-based potting mix. Adding perlite or vermiculite will help the soil's porosity.

Plant the tree at the same height it was in its nursery container, tamping the soil firmly around the root ball to eliminate air pockets. Slowly water until the potting mix is fully saturated. A potted pine tree will need more frequent watering than an in-ground tree, And because nutrients leach out of the soil faster, a potted pine tree will appreciate a yearly small dose of slow-release fertilizer. Avoid heavy fertilizing, though, as this can make the tree grow too fast.

Pine trees generally grow well with confined roots, so repotting won't be a frequent task. When the tree finally does become root-bound, the best repotting strategy is to carefully remove it from the pot, trim back about one-third of its root mass, then repot in the same container using fresh potting mix.

Overwintering

Once they are mature, Austrian pines in the landscape will usually not require protection against winter cold if they are being grown within their established hardiness range. Young trees will benefit from a thick layer of dry mulch placed over the root zone for winter. If the fall has been dry, water thoroughly in the fall to prevent desiccation over the winter months.

Potted Austrian pines must be moved to a sheltered location for the winter, such as a garage or shed. Another option is the bury the container in the ground up to the rim for the winter months. Left above ground and unprotected, a potted tree's roots may die.

Common Pests and Plant Diseases

The Austrian pine is prey to many fungal diseases, such as lophodermium needle cast, diplodia (sphaeropsis) tip blight, as well as various wood rots and decays. Remove affected branches as you spot them. Spraying with fungicide may slow the spread, but once infected, it is hard to save a tree.

Insect pests include the European pine sawfly, weevils, and Zimmerman pine moth. The tree is also frequently damaged by yellow-bellied sapsuckers feeding on the many insects that infest it. Spraying with horticultural oil may lessen insect damage, though this is difficult with a large established tree.

The many problems with Austrian pine are so pronounced that the use of the tree is discouraged in many regions.

Common Problems With Austrian Pine

Aside from its susceptibility to pests and fungal diseases, Austrian pine can be susceptible to wind damage, especially in the winter if heavy snows weigh down the branches. Prune away dead branches as you spot them. With young trees, shake off heavy snow from the branches to reduce weight.