Transplanting

Most often this takes the form of starting a plant from seed in optimal conditions, such as in a greenhouse or protected nursery bed, then replanting it in another, usually outdoor, growing location.

Some containers are designed to be planted with the tree e.g., the tar paper pot, the Alberta peat sausage, the Walters square bullet, and paper pot systems, are filled with rooting medium and planted with the tree (Tinus and McDonald 1979).

Most containers are tube-like; both diameter and volume affect white spruce growth (Hocking and Mitchell 1975, Carlson and Endean 1976).

However, the biological advantage of size has been enough to influence a pronounced swing towards larger containers in British Columbia (Coates et al.

[9] The BC-CFS Styroblock plug, developed in 1969/70, has become the dominant stock type for interior spruce in British Columbia (Van Eerden and Gates 1990, Coates et al.

As advocated by Coates et al. (1994),[8] thawed planting stock taken to the field should optimally be kept cool at 1 °C to 2 °C in relative humidities over 90% (Ronco 1972a).

Binder and Fielder (1988)[11] recommended that boxed seedlings retrieved from cold storage should not be exposed to temperatures above 10 °C.

Refrigerator vans commonly used for transportation and on-site storage normally ‘maintain seedlings at 2 °C to 4 °C (Mitchell et al.

Coniferous planting stock is often held in frozen storage, mostly at −2 °C, for extended periods and then cool-stored (+2 °C) to thaw the root plug prior to outplanting.

Physiological activity is also greater under cool rather than frozen storage, but seedlings of interior spruce and Engelmann spruce that were planted while still frozen had only brief and transient physiological effects, including xylem water potential, (Camm et al. 1995, Silem and Guy 1998).

[20] Kooistra and Bakker (2002)[21] noted several lines of evidence suggesting that cool storage can have negative effects on seedling health.

[22] As well, Silem and Guy (1998),[15] for instance, found that interior spruce seedlings had significantly lower total carbohydrate reserves if stored for 2 weeks at 2 °C than if thawed rapidly for 24 hours at 15 °C.

Seedlings can rapidly lose cold hardiness in cool storage through increased respiration and consumption of intracellular sugars that function as cryoprotectants (Ogren 1997).