Conifer Questions and Answers

Conifer Questions and Answers

What conditions do I need to grow conifers?

Depending on your soil type, available sunlight, and climate, you can choose a conifer that is very likely to succeed no matter where you live. For most conifers, slightly acid soil that is loamy and well-drained is ideal. Hemlock, dawn redwood, baldcypress, and Atlantic white cedar like soil that stays consistently moist while junipers, pines, and the true cedars are well-adapted to dry conditions. Black spruce, balsam fir, and Siberian cypress are at home where winters are bitterly cold while Arizona cypress, Japanese cedar, and deodar cedar thrive in warm temperate areas. Most conifers grow best in full sun, but a bit of afternoon shade is best for the dwarf conifers in hot southern zones. Hemlock, yew, and plumyew tolerate shade well.

When and how do I plant a conifer?

It's best to plant conifers in early autumn unless you live in an area where winters are bitterly cold. In the cool days of autumn, they have more time to make root growth in moist soil. Since good drainage through the soil and ample pore spaces for air are key to the survival of conifer roots, be careful not to plant them too deeply, especially if your soil is heavy or has a lot of clay in it. If you plant a conifer that was grown in a container, prune off any roots that encircle the outside of the root ball. If it was dug and transported with burlap and twine around the root ball, remove as much of the burlap, ties, and wire as you possibly can without injuring the roots. It's best not to amend the soil in the planting site. Compost or peat moss might pamper the roots and discourage the development of a broad, expansive root system. Stake your new tree only if it is planted in a windy location, and apply a couple of inches of shredded hardwood or pine bark mulch to the root zone to preserve soil moisture. Keep the mulch at least six inches away from the trunk. Water deeply and infrequently so the soil stays evenly moist at its depths but dries out partially at the surface between waterings. After the tree has established itself and begun to grow, remove any stakes and wires that were used to support it.

What makes a dwarf conifer dwarf?

Dwarf conifers are dwarf because of their genetics. A single bud in a normal tree may change its genetics and produce a clump of densely branched, dwarf growth. These growths are called witches brooms. Other dwarf conifers originated as slow growing individuals in a population propagated from seed. Dwarf conifers are often propagated by grafting since they are usually difficult to root and will not come true from seed.

How should I prune my conifers?

Conifers, unlike many deciduous and broad-leaved trees and shrubs, should never be pruned too drastically since most of them cannot sprout new growth from old wood.  Yew and baldcypress are exceptions to this general rule and can sprout new growth even if cut back severely.

Never remove more than one third of the total growth at one time, and be sure to leave some green tissue that has potential to produce new growth.  Never remove all of the green portion of conifers like juniper and arborvitae by shearing them.  Removal of much of the green growth can result in a permanently misshapen plant or death of the plant.  Control the size of sprawling conifers by pruning the longest branches back to where they meet with a shorter branch.

Pines can be shaped and forced to produce denser growth by a pruning technique known as candling.  Candles are the elongated shoots produced at the beginning of each flush of growth.  After the candles are fully grown, needles grow out of the candles.  The candles can branch while they are growing if they are pruned before the needles begin to emerge.  Break off about two-thirds of the candle with your fingers.  Don't use pruners since you are likely to damage remaining needles, causing them to look unsightly.

What are some other sources for information about conifers?

If you're interested in buying some conifers, ask your local nursery or extension educator for information on those that can be grown in your area. If you are looking for a particular variety, check National Arboretum's Plant Sources Page for tips on finding a supplier.

For the basics on gardening with conifers, look for the Brooklyn Botanic Garden handbook titled Growing Conifers Four Season Plants. Visit www.bbg.org for ordering information.

The Gotelli Collection of Dwarf and Slow Growing Conifers is the subject of Sandra McLean Cutler's book titled Dwarf and Unusual Conifers Coming of Age. It is available from the publisher at www.bartonbradley.com.

If you're a conifer lover, you can join other conifer enthusiasts by visiting the American Conifer Society at www.conifersociety.org.

Source - The United States National Arboretum