Conifers are beautiful additions to landscapes, providing year-round colour and interest for decades. The wide family includes a variety of evergreen ground covers, shrubs and trees such as pine, fir, arbor vitae, yew and spruce. Although termed as evergreens, conifers are not necessarily green but come in a rainbow of colours including lavender, blue and yellow, depending on the variety. Caring for the winter-hardy, cone-producing plants includes following a regular and consistent irrigation, fertilisation and pruning schedule to face fewer problems.
Plant the conifer in well-draining, fertile soil in fall, when it is dormant, with full sunlight to partial shade exposure. Dig a planting hole two times as wide as the root ball but equally deep, so the root collar is at or slightly below the soil line.
Irrigate the soil soon after planting using a soaker hose or trickle irrigation system that provides water to a depth of 12 inches. Water newly planted or young conifers two times a week until established. For established conifers, water the soil when the top 1 to 2 inches feels dry. Water the tree deeply in early to midfall, and reduce irrigation for the winter, especially if your area faces extreme freezes.
Mulch the soil around the base of the conifer to protect roots from extreme temperatures and prevent weeds. Space organic mulch such as wood chips, compost, pine straw, shredded pine bark or dried leaves six inches away from the trunk to prevent rot. Maintain the 2- to 3-inch-thick layer of mulch all year round.
Feed each conifer tree a well-balanced, 10-10-10 fertiliser in spring of the second year and annually afterward. Spread 0.907kg. of the fertiliser per inch of trunk diameter evenly around the base of the tree, spaced 10 inches from the trunk.
Prune conifers in late winter or early spring using sharp sterilised pruning shears to clip off dead, damaged or diseased limbs. Determine the interior dead zone on arbor vitae and junipers -- the growth within the interior of the plant beyond which you cannot prune, so you know your pruning limitations. Pruning pines differs from other conifers, because they do not develop a dead zone. Instead, prune the tree into a pyramidal shape, with a central leader and evenly spaced branches along the sides. Do not top or remove upper growth on a conifer tree.
Inspect the conifer for symptoms of dieback that includes needle discolouration and premature needle drop. Follow proper cultural practices to remedy the problem. Look out for needle diseases such as brown spot, tip blight and rhizosphaera needle cast, and treat immediately with a registered fungicide to prevent spread.
- Iowa State University Extension; Pine, Fir or Spruce Tree?; Tivon Feeley; November 2005
- University of Idaho; How to Prune Coniferous Evergreen Trees; D.W. McConnell, et al.; 1985
- Purdue University Extension; Conifer Dieback; Gail Ruhl, et al.; April 2011
- Iowa State University Extension; Conifer Needle Diseases; Barbara Ambruzs; April 2002
- Although some conifers are moderately drought tolerant, maintaining a regular watering schedule encourages green and healthy needles.
- Avoid overwatering the soil or creating pools of water at the base of the conifer when irrigating it.
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