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The Facility There are two major methods of containerized seedling production: unheated production in cold frames and production in heated greenhouses. Harrington Tree Nursery enjoys the benefits of both. The tree nursery operates year round. 
Cold Frames
A cold frame is similar to a greenhouse but is not equipped with a heating and automatic venting system. Each cold frame may hold from 70,000 large seedlings to over 300,000 small size plugs. The cold frames offer a more moderate climate than a completely exposed open compound. They have neither supplementary heat nor light and thus require a less intensive cultural regime than greenhouses. However, automatic irrigation and fertilization systems must be used. Crops are started from the end of April to the end of May. The growing season lasts through September. Dormancy induction and frost hardening are done naturally at the end of the season. The plastic covering is removed when dormancy is induced and seedlings become tolerant to frost. The snow insulates the seedlings and protects them from frigid winter temperatures. Trays are taken out to adjacent growing areas either in the fall or the following spring before the next seeding takes place. The type of seedling grown (tray, species, size) will dictate the growing practice. The cold frame production system takes two years from sowing to planting. This system requires an adjacent outside growing area twice as large as the cold frames themselves to assure a good crop rotation.
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Heated Greenhouses
The production of forest seedlings in greenhouses requires a significant investment in greenhouse infrastructures. With these heated greenhouses, it becomes possible to grow two crops of seedlings per year. If seeded in January, a crop can be ready for planting by early summer of the same year. A second crop can be seeded in May immediately after the first crop is placed outside in shadehouses. The summer crop is grown and hardened-off inside the greenhouse. The seedlings are then taken to an outdoor holding area for the winter and ready for planting the following spring. It can take from 6 to 10 months to grow a “ready to plant” seedling in a greenhouse. Greenhouses can also permit an early spring seeding (March or April) to produce a suitable seedling by late fall. This growth calendar is perfectly suited for seedlings that need to be extracted and left dormant in cold storage for planting the following spring.At Harrington, greenhouses are heated with a bi-energy system: 2 electric furnaces requiring 450 kw each for a capacity of 1.5 million BTU each, plus two (2) oil furnaces with a capacity of 2.8 million BTU each. The 2 systems can work separately or simultaneously. The heating is a low-pressure water system. Uniform and reliable heat is supplied through air exchangers located in the middle of each bay under the growing benches in greenhouses. In case of power failure, a 185 kw generator starts automatically to keep the oil burners going, as well as pumps, lights and other domestic utilities. The gutter-connected greenhouses have automated top circulating fans and vented roofing. Each greenhouse has its own aquaboom with mounted injector. The growing benches roll on tracks and are adapted to a variety of trays. Rolling benches can be transferred out of the greenhouses to the shadehouses at either end for maximum efficiency. The gutter-connected greenhouses are adjacent to the potting room. This is very efficient, particularly for the winter crop. High-pressure sodium lamps are used during winter months to expand the daylight; shade covers are utilized during summer and fall months to adjust the desired level of light for growth. The two-crop rotation production system in heated greenhouses requires as much space in the shadehouses and holding areas as the greenhouses themselves to assure a good crop rotation.
Irrigation/Fertigation System Harrington is equipped with the aqua-boom system which provides concurrent uniform watering and accurate fertilization. A mobile sprayer is also employed for fertilization and pest control for all outside growing areas. |
Harrington Tree Nursery has an excellent water supply. The water is pumped from a one-acre man-made pond that is spring-fed. The water is of good quality for growing trees having a slight alkalinity level and rich in bicarbonates. Three irrigation pumps run the filtered water through an underground network of irrigation lines that are located throughout the 10 acres of growing area. All outside compounds are equipped with sprinklers to allow for watering, and for protection in case of a late spring frost.