Fertilizer Regimes for Container- Grown Conifers of the Intermountain West

In the Intermountain West, defined here as eastern Washington, northern Idaho, and western Montana, nine nurseries grow about 12-18 million container seedlings annually for reforestation. Although as many as a dozen species may be grown for reforestation, the bulk of nursery production is represented by four species (Table 1). Nearly two-thirds of the nurseries have structures with roll-up sides or move crops to shadehouses for part of the growing season. Currently, most nurseries use a 1:1 peat:vermiculite growing medium, although a rapid conversion to a 70:30 peat:sawdust medium is occurring and will probably be the standard within three to five years, if not sooner. The preferred container consists of a styrofoam block separated into individual cavities. Volume of the cavities used in nurseries run the gamut from 2 to 20 in3 (40 to 340 ml; i.e., Ventblock 240/40 to 45/340), although most seedlings are grown in containers with either a 4- or 5-in 3 volume cavity (65 or 90 ml; i.e., Ventblock 160/65 or 160/90) and 80 seedlings per ft 2 (890 per m2 ). There is an emerging trend for larger volumes, with 10 in 3 (170 ml; i.e., Ventblock 77/170) being the most common. Only one nursery routinely uses copperblocks (styrofoam blocks treated with copper to chemically root prune seedlings).

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Author(s): R. Kasten Dumroese, David L. Wenny

Event: Symposium Proceedings: Forest Seedling Nutrition from the Nursery to the Field
1997