Monterey pine is normally planted as small nursery container-grown specimen—or simple seedling—in early spring or fall. It is one of the fastest-growing of all pines, adding 3 to 6 feet per year. In ideal conditions, the tree can reach 80 feet within 20 years. There are instances of older trees approaching 200 feet in height. The tree is best planted in fertile but sandy soil, in a spot that gets full sun to partial shade, spaced 40 or 50 feet from buildings and other large trees. Monterey pine grows into a very large tree surprisingly fast, so give it plenty of space. Unlike many landscape trees, Monterey pine is best planted as a relatively small potted plant or even a new seedling. These trees have long tap roots can become root bound in containers, and larger nursery specimens have a tendency to languish after planting. A 1-foot-tall seedling, on the other hand, may quickly outgrow a 6-foot container-grown tree Provided the tree can avoid various bark beetles and fungal cankers, it is fairly easy to maintain, usually surviving on ambient rainfall and rarely needing pruning. Be aware that Monterey pine will readily self-seed and be on the lookout for invasive volunteers sprouting up in nearby areas.
Light
Monterey pine trees can grow in a range of full sun to partial shade locations. The native range of Monterey pine includes regions that are sunny most days of the year. If planting a Monterey pine tree as a specimen in your landscape, try to choose a spot that gets at least six to eight hours of sunlight daily. Because the tree grows so fast, it will quickly grow beyond a partial shade location as it reaches upward.
Soil
To reach their majestic height, Monterey pine trees need to be planted in fairly nutrient-rich soil with good drainage. The tree also grows best in soil that has a fair amount of sandstone nearby, hence its success growing in coastal areas, like dunes or bluffs. The soil surrounding the tree must be very deep in order to allow plenty of space for the roots; if the roots hit a rock, the tree can become unstable over time.
Water
Regular watering is key to helping a young Monterey pine tree get established. Once the tree is established (after two to three months), it will be moderately drought tolerant and will need to be watered only during extended periods of dryness. If you notice that your tree is dropping an excessive number of needles, that’s a good indicator that the tree is in need of some water.
Temperature and Humidity
This pine is considered suitable for USDA zones 7 to 10. While Monterey pine trees can tolerate temperatures as low as 20 degrees Fahrenheit, they should get only brief exposure to that type of weather and will not flourish in areas that dip consistently below freezing. The trees are also humidity lovers and are happiest and healthiest when growing on coastal bluffs and soaking in the salty sea air.
Fertilizer
Fertilizer can cause these fast-growing trees to overgrow, so they should not be fed at all.
Types of Monterey Pine
There are no named cultivars of Pinus radiata, but there are three naturally occurring varieties:
P. radiata var. radiata is the typical form that is normally sold as a landscape tree. It is also the type cultivated worldwide for commercial lumber.P. radiata var. binata is a native tree found on Guadalupe Island, Mexico. P. radiata var. cedrosensis is found on Cedros Island, Mexico.
Pruning
Regular pruning is not necessary for this tree, but it can be done to remove damaged or diseased branches or to remove low-hanging branches to raise the canopy. If a tree has excessively long branches, they can be cut back by about one-third of their total length to reduce stress on the tree and prevent wind damage. And branches that touch or approach the house or other buildings should be cut back, as these resinous trees pose a distinct danger during wildfires. October to January is the best time to prune, as this is the dormant period for the beetles that can cause open wounds through which fungal diseases can enter.
Propagating Monterey Pine
Monterey pine is almost always propagated by germinating seeds and planting the tiny seedlings when they are just a few inches tall. Here’s how to do it: Although it is a less common method, Monterey pine can also be reproduced from semi-hardwood cuttings taken in late fall. Plant the cuttings in containers filled with sandy potting mix, keep moist through frequent misting, until the cuttings develop roots. This can take as long as 22 weeks. Cuttings taken from young trees are most likely to succeed.
Overwintering
Monterey pine needs no protection against winter cold, but tiny seedlings may become a food source for deer, rabbits, and other creatures unless you protect them with cages made of hardware cloth for the first year or two. After this, they are safe from serious animal damage. In areas where bark beetles and resulting fungal diseases are common, spraying the tree with horticultural oil in late winter can help control overwintering pests.
Common Pests and Plant Diseases
Monterey pines are free of most serious life-threatening pest problems, though they can experience minor damage from many insects, including needle miners, midges, weevils, scale, mites, and nematodes. A truly life-threatening problem is created by various bark beetles that can penetrate into the tree, thereby facilitating infection by serious fungal organisms. Prevent bark beetles by pruning only during times when the beetles are dormant, or by applying recommended pesticides (consult local tree experts for advice). An overwintering spray of horticultural oil is often an effective method. There are a few harsh diseases to which these trees are especially susceptible. One of the biggest issues for pine trees of all types (including the Monterey pine), is pitch canker, a fungal disease that causes swollen lesions to appear on the tree’s trunk, branches, and roots. The lesions can prevent the tree from getting water, causing the needles to turn red, dry up, and eventually die off. At one time, it was feared that the Fusarium circinatum fungus might destroy all Monterey pines in the native range, but the species has developed some acquired resistance and is no longer so seriously threatened. An affected tree that is carefully tended may survive the disease, and a systemic soak with fungicide, applied by a professional, can sometimes save an infected tree. Other common diseases for the Monterey pine tree include root rot, needle blight, and tip blight. While not much can be done if an enormous tree becomes seriously infected, you can remove any diseased plants and keep the base of any specimen trees clear of debris or rotting foliage in order to prevent spread.
How to Get Monterey Pine to Bloom
The creamy whitish brown flowers that appear in winter are very small and nondescript, so there is no reason to encourage Monterey pine to bloom.
Common Problems With Monterey Pine
The most common issues with Monterey pine include fungal disease (see above), but there are some other common complaints:
Tree Is Too Large
In ideal locations, the growth rate of a Monterey pine can be prodigious. There are cases of this tree achieving as much as 6 feet per year, and if the location was not carefully considered at planting time, it may overwhelm the landscape. But these trees do accept rather hard pruning; you can cut back branches by one-third of their total length every few years, if necessary. But it’s also possible that you will need to have the tree removed if the size becomes unmanageable.
Tips of Needles Turn Brown
There can be several causes for this symptom, including insect damage or reaction to pesticides. But more commonly, Monterey pine may experience damaged needles in response to environmental pollution. This is not a tree well-suited to inner-city urban areas or neighborhoods near freeways.
Tree Blew Down in a Storm
This very often occurs if a Monterey pine has been planted in shallow soil so that the long taproot that normally anchors the tree has been dead-ended by shallow underlying bedrock. If you replant a new Monterey pine, try to verify that the soil is unimpeded to a depth of 5 feet or more. In areas where the soil structure has an underlying hardpan layer, a special “ripping” operation may be needed to break up the hardpan and allow space for a Monterey pine’s taproot to take hold.
