Smart tips for growing white pine trees

The white pines are outstanding, aromatic landscape trees native to large areas of North America. Here are some smart tips for selecting and growing white pine trees in your outdoor space.

• The Eastern white pine (Pinus strobus) is among the tallest trees on the eastern part of the continent, reaching about 7.5 metres (25 feet) in 20 years and eventually reaching 45 metres (150 feet) at maturity. It is also one of the most beautiful.
• The tree grows into an irregular pyramid, and has 12-centimetre-long (five-inch-long) green needles with a bluish tint. The needles are soft to the touch, making this a choice pine tree to grow where people will be walking nearby.
• While eastern white pine cannot tolerate salt or air pollution, it does tolerate up to a half day of shade, which means it can grow happily alongside flowering dogwoods, serviceberries, and rhododendrons. It can also adapt to many types of soil as long as the site has good drainage.
• Western white pine (P. monticola), which is native to the Pacific coast, is similar, although it forms a narrower, more symmetrical pyramid that tops out at 25 metres (80 feet). The needles are brighter green and grow 10 centimetres (four inches) long. The western white pine is ideal for specimens, groupings, and screens, and is hardy from Zone 7.

• Plant white pine in spring or early fall in well-drained soil, keeping the soil ball intact to prevent root damage.
• If the root ball is skimpy, it may be necessary to stake young trees to secure them against strong wind.
• Expect newly planted trees to grow slowly for two to three years, then suddenly gain size. Until new growth is vigorous, water during droughts by soaking the root zone every seven to ten days.
• Nurseries often force white pines to produce dense branches by clipping back the "candles", or growth tips, by about half in early summer. But this can cause double leaders to form at the crown, which are weak compared to a single leader.
• In the landscape, it is best to leave white pines unpruned unless you want to remove low branches to make it possible to walk or sit under the trees. Do this job in spring, while the trees are young, to limit the number of bumpy calluses that form on the main trunk.
• Unlike other pines, white pine is not very susceptible to the pine-wilt nematode that slowly kills trees. It is also more resistant to sawflies, tip blights, and other common needle diseases.
• Occasionally white pine aphids attack, evidenced by splatters of white residue on the bark. Treat this insect pest with an garden insecticide labeled for white pine and the pest, applying as directed on the label.

There are numerous varieties of white pines, offering different sizes, colours, and growth habits.

• Among the eastern white pines, 'Nana' is a dense, round dwarf useful for rock gardens and edging.
• 'Pendula' is a weeping form, while 'Fastigiata' grows upright.
• 'Blue Shag' has blue foliage, and 'Nivea' has bluish needles tipped in white.
• Several western white pines also have pronounced blue foliage including the slender 'Skyline', vigorous 'Ammerland', and dwarf 'Minima.'

White pines are beautiful additions to any landscape. Consider these tips and grow a white pine that will thrive in your outdoor space.