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Introduction to Forest Nursery Management

Create by Dr. Tom Landis, USDA Forest Service 2001


80 Images
0010001
Thomas D. 'Tom' Landis
USDA Forest Service

By far, the majority of forest and conservation tree seedlings are grown from seed, and most of this seed is collected from plants in the wild. Because seedlings must be genetically-adapted to the environment on the outplanting site, foresters insist on "source-identified" seed. Seed collected from a specific location in a particular year is called a "seed lot", and is identified by a numerical seed code. When the seed is sown, this seed code will identify the seedlings until they are shipped back to the same geographical location for outplanting.

0010002
Thomas D. 'Tom' Landis
USDA Forest Service

Sometimes, seed orchards are established to produce seed of trees that have been specially selected for fast growth or pest resistance. In this slide, seeds of western white pine (Pinus monticola) are being collected at the seed orchard at the Coeur d’ Alene Nursery in Idaho. This seed orchard was established using plant material selected for resistance to the white pine blister rust fungus (Cronartium ribicolae)

0010003
Thomas D. 'Tom' Landis
USDA Forest Service

The quality of the seed lot is established by a germination test, which measures how many seeds will germinate under the ideal conditions. For nurseries that do not have a germination chamber, these tests can be done for a fee at the National Tree Seed Laboratory or a private seed testing laboratory.

0010004
Thomas D. 'Tom' Landis
USDA Forest Service

Most forest tree seeds are dormant and must be treated before they will germinate. The dormancy requirement of most commercial tree species can be satisfied by a cold, moist stratification treatment. The seeds are soaked for 24 to 48 hours, and then placed in plastic bags in a refrigerator for a period of 2 to 6 months, depending on the species.

0010005
Thomas D. 'Tom' Landis
USDA Forest Service

Bareroot seedlings take from 1 to 3 years to produce, depending on the species and the location of the nursery. A typical crop rotation for this 2+0 ponderosa pine is 2 years in the seedbed, followed by a 1 year rest or fallow period.

0010006
Thomas D. 'Tom' Landis
USDA Forest Service

A cover or green manure crop is typically grown during the fallow year. A cover crop protects the soil from wind and water erosion and controls weeds, whereas a green manure crop is primarily grown to supply organic matter to the soil. These crops also capture mineral nutrients, such as phosphorus and iron, in a readily-available form. The cover crop is plowed down in the late summer to allow time for the organic matter to decompose.

0010007
Thomas D. 'Tom' Landis
USDA Forest Service

In addition to the organic matter supplied by the cover crop, many nurseries add organic amendments such as sawdust during the fallow year. Nitrogen fertilizer is added at the same time to speed the decomposition rate; if no fertilizer is supplied, the microorganisms will utilize all the nitrogen in the soil and cause a deficiency in the subsequent seedling crop.

0010008
Thomas D. 'Tom' Landis
USDA Forest Service

Because of the frequent use of heavy equipment during periods when the soil is wet, soil compaction is a serious and reoccurring problem in forest nurseries. Many nurseries "deep rip" their soils with long shanks during the rest year. This operation is often done immediately after the organic matter application so that the sawdust can be incorporated throughout the soil profile, and prevent the formation of soil pans.

0010009
Thomas D. 'Tom' Landis
USDA Forest Service

Most of the larger bareroot nurseries fumigate their seedbeds with a poisonous gas, such as methyl bromide/chloropicrin, to sterilize the soil. Fumigation is expensive, but eliminates all the common nursery pests: pathogenic fungi, insects, nematodes, and weed seeds. The fumigant is injected into the soil and then immediately covered with a plastic tarp, allowing the gas to permeate throughout the soil. After several days, the tarp is removed, the gas dissipates, and the soil is ready to plant. Currently, the use of methyl bromide is being curtailed because of potential damage to the ozone layer.

0010010
Thomas D. 'Tom' Landis
USDA Forest Service

The next cultural operation is to add the "pre-plant" fertilizer amendments. Based on tests, the soil pH can be adjusted to the ideal range of 5.5 to 6.5 by adding dolomite to raise the pH, or sulfur to lower it. Phosphorus fertilizer is often incorporated into the soil at this time, rather than as a top dressing during the growing season because phosphorus is not mobile in the soil. Often, these amendments are applied immediately before the soil is formed into the typical raised seedbeds. Seedbeds are approximately 4 ft. wide, a standard dimension that corresponds to all mechanized equipment that is used in forest nurseries.

0010011
Thomas D. 'Tom' Landis
USDA Forest Service

After the seedbeds are formed, the seed is sown. Some nurseries sow in the fall so that the seeds can undergo natural stratification. Spring sowing is more common, however, and begins as soon as soil temperatures are warm enough. Larger nurseries use seed drills which sow the seed in 6 to 8 rows per seedbed. Some seed drills automatically cover the seed with soil, whereas others leave the seed exposed so that it can be covered with a mulch. The number of seeds that are sown per area of seedbed is determined by a ‘sowing factor’ that includes information on seed germination, desired seedling growing density, expected seedling survival etc

0010012
Thomas D. 'Tom' Landis
USDA Forest Service

Nurseries without sowing equipments, hand sow their seeds in the seedbed. It is more difficult to control seed spacing with this broadcast sowing, however, and so seedling density can often be too sparse or too dense as in this slide.

0010013
Thomas D. 'Tom' Landis
USDA Forest Service

Some nurseries cover the sown seedbed with soil wherease others use a mulch, such as hydromulch. Mulches serve several functions, including controlling soil erosion, retarding moisture loss, and reducing soil temperature.

0010014
Thomas D. 'Tom' Landis
USDA Forest Service

All seed is sown by seedlot, and each different lot is immediately labeled with some sort of marker that contains all pertinent information. The location of all seedlots is also permanently mapped in case the markers are lost. The identity of each seedlot is carefully maintained during the entire nursery operation to make sure that the seedlings are returned to the environment to which they are adapted. In the Western States, some nurseries sow literally hundreds of different seedlots each year that reflect the many diverse environments in that mountainous terrain.

0010015
Thomas D. 'Tom' Landis
USDA Forest Service

Chemical herbicides are immediately applied to the sown seedbeds. These "pre-emergence" herbicides selectively kill the germinating weeds but do not harm the tree seedlings. If weeds become a serious problem later in the growing season, then a "post-emergence" herbicide is sometimes applied over the top of the seedlings. Unfortunately, not all weeds can be controlled with herbicides so nursery workers must remove them by hand-weeding.

0010016
Thomas D. 'Tom' Landis
USDA Forest Service

The newly-sown seedbeds are kept "moist, but not wet" and seeds germinate within a few weeks. The overhead sprinkler irrigation not only supplies water for seedling growth, but also is used to cool the soil surface while the new germinants are still succulent. Irrigation can also provide protection against late fall or early spring frosts.

0010017
Thomas D. 'Tom' Landis
USDA Forest Service

Bareroot nurseries apply the mineral nutrients that are needed for rapid growth with chemical fertilizers. Unless soil tests show other nutrient deficiencies, nitrogen and potassium are the only fertilizers that are typically applied - remember that phosphorus is typically applied before sowing. During the growing season applications are called "top dressings" because they are done over the top of the crop. The application rates are determined by experience or from chemical tests of the soil and seedling foliage.

0010018
Thomas D. 'Tom' Landis
USDA Forest Service

Root culturing is one of the most important nursery operations because a tree seedling is only as good as its root system. During the latter part of the first growing season, seedbeds are undercut with a horizontal blade to severe the dominant tap roots and promote a more fibrous root system. Wrenching is a special type of undercutting that uses an angled blade to shatter the soil profile, and increases the soil permeability and aeration. Wrenching also induces a temporary seedling moisture stress which can be used to retard shoot growth and induce dormancy.

0010019
Thomas D. 'Tom' Landis
USDA Forest Service

The lateral roots between the seed rows are also pruned with a vertical root pruner. This piece of equipment is sometimes "belly-mounted" under the tractor which allows precise placement by the tractor operator.

0010020
Thomas D. 'Tom' Landis
USDA Forest Service

Some nurseries top prune their seedlings to control shoot height. This practice also increases crop uniformity because it exposes smaller plants which were overtopped by larger ones. The timing of top pruning is extremely critical so that the seedlings are not injured or stimulated to produce abnormal shoot growth.

0010021
Thomas D. 'Tom' Landis
USDA Forest Service

Seedbeds are sampled each year to determine the current inventory. In addition to counting the number of live seedlings per area of seedbed, the inventory crews measure the height and stem diameter of the crop to get an estimate of how many seedlings will make "shippable" grade by the time of harvest.

0010022
Thomas D. 'Tom' Landis
USDA Forest Service

All of these cultural practices are aimed at producing a uniform crop of seedlings that meet the morphological and physiological specifications of the customer.

0010023
Thomas D. 'Tom' Landis
USDA Forest Service

Not all forest and conservation plants can be produced from seed. Some species, such as willow and cottonwood, can be propagated more efficiently with hardwood cuttings. Shoots are collected during the winter dormant period, are cut into sections, and stored under refrigeration until they can be planted the following spring.

0010024
Thomas D. 'Tom' Landis
USDA Forest Service

Cuttings grow relatively faster than seedlings so a crop can usually be grown in only one growing season.

0010025
Thomas D. 'Tom' Landis
USDA Forest Service

At the end of the crop cycle, the seedlings are ready for harvest. Harvesting, or "lifting", is done during the dormant period when the seedlings are in a state of maximum hardiness, or resistance to stress. This time period is known as the "lifting window" and occurs during the late fall, winter, or early spring. In nurseries where the ground freezes, there are two narrow lifting windows: one in the fall, and another in the spring. Because the weather is often too wet in the spring, some nurseries lift a significant portion of their crop in the fall.

0010026
Thomas D. 'Tom' Landis
USDA Forest Service

Lifting consists of drawing an inclined, vibrating blade under the seedlings, usually at a depth of about one foot. The inclined blade lifts the seedlings out of the seedbed and the vibrating action loosens the soil from around the roots.

0010027
Thomas D. 'Tom' Landis
USDA Forest Service

Hand lifting consists of pulling the seedlings from the soil by hand, shaking the loosened soil from the roots, and placing them in a box. The lifting boxes are lined with wet burlap to keep the seedling roots from drying out.

0010028
Thomas D. 'Tom' Landis
USDA Forest Service

Several different types of mechanical harvesters are also used to lift seedlings. Most use a digger blade to lift the entire seedbed width onto a moving, vibrating belt that shakes the soil from the roots. They are then placed into boxes for transport to the pre-storage cooler.

0010029
Thomas D. 'Tom' Landis
USDA Forest Service

The time period from when the seedling are lifted until they are outplanted is one of the most critical in the entire reforestation sequence. The tiny fibrous roots are especially prone to drying and can be killed by a few minutes of exposure to heat or direct sunlight. The lifting crew includes several people that are assigned to keep the seedling boxes wet until they can be moved to the pre-storage cooler.

0010030
Thomas D. 'Tom' Landis
USDA Forest Service

Progressive nurseries monitor seedling quality during the seedling harvesting to outplanting operation. The pressure chamber directly measures seedling moisture stress and is used to determine when weather conditions are too dry to lift, and to identify potential problems.

0010031
Thomas D. 'Tom' Landis
USDA Forest Service

Boxes of seedlings are brought into the packing shed where the seedlings are graded and counted. The workers visually rate each seedling according to predetermined grading standards.

0010032
Thomas D. 'Tom' Landis
USDA Forest Service

Bundles of "shippable" seedlings are placed on a moving belt, and "culls" are discarded onto the floor and destroyed. Seedlings that have been grown especially for transplanting are also graded in this manner, and some nurseries use a multiple grading system: shippable, transplants, and culls.

0010033
Thomas D. 'Tom' Landis
USDA Forest Service

Grading standards are determined by the customer, depending on their intended use. Larger seedlings are needed for moist planting sites where planting competition is severe, or on sites where animal damage is serious. Shorter, stockier seedlings with a proportionally larger root system are required for harsher, drier planting sites. Often, the nursery manager negotiates these standards with the customer when the seedling order is taken. Grading standards usually consist of a range of acceptable shoot heights, a minimum acceptable caliper (stem diameter), and the length and fibrosity of the root system. Of course, the seed code for the specific seed lot is also carefully monitored during the grading process.

0010034
Thomas D. 'Tom' Landis
USDA Forest Service

Shippable seedlings are placed in moisture retaining boxes or bags, and sphagnum moss is sometimes added to the bag to keep the roots moist. The seed code is marked on each bag or box as they are filled with seedlings.

0010035
Thomas D. 'Tom' Landis
USDA Forest Service

Storage containers are transported to a cooler where they are kept at temperatures near freezing to maintain dormancy and cold hardiness. Each box is marked with the proper seed source code which describes the origin of the seedlot.

0010036
Thomas D. 'Tom' Landis
USDA Forest Service

Cold storage facilities keep the ambient temperature near freezing, but it is important to monitor the temperature inside the storage container. For long term storage of more than 3 months, some nurseries utilize coolers that keep the storage temperature at slightly below freezing. Research has shown that frozen storage can maintain high seedling quality for over 6 months, and also retards the development of storage molds.

0010037
Thomas D. 'Tom' Landis
USDA Forest Service

Hardwood seedlings are sometimes "heeled-in" in outside beds until they can be outplanted. This process is normally only used where refrigerated storage is not available. Heeling-in is effective because dormant hardwoods have lost their leaves and therefore loose little moisture through transpiration. Seedling dormancy cannot be maintained under these conditions, however.

0010038
Thomas D. 'Tom' Landis
USDA Forest Service

Transplants are grown when the customer wants a larger, more robust plant. A typical transplant is grown for one year, and then planted back into nursery beds and grown for another 1 to 2 years. Nurseries either grow seedlings specifically for transplanting, or use smaller stock that have been graded for transplanting. Mechanical transplanters use a vertical "shoe" to open the soil, and a wheel with clips places the seedlings into the slit at the proper spacing.

0010039
Thomas D. 'Tom' Landis
USDA Forest Service

Transplants are planted into rows, and the beds look similar to seedbeds except that the growing density is less to allow for faster growth. Transplant beds are fertilized, irrigated, and have the same root culture treatments as do bareroot seedlings. The transplanting process creates better caliper and roots than a comparably-sized seedling. Transplants are used for harsher outplanting sites, where animal browsing is a problem, or plant competition is severe.

0010040
Thomas D. 'Tom' Landis
USDA Forest Service

The end of the bareroot nursery process comes when the seedlings, cuttings, or transplants are shipped to the outplanting site, which is in the same general geographical region where the seed or cuttings were collected.

0010041
Thomas D. 'Tom' Landis
USDA Forest Service

The second way to produce forest and conservation seedlings is in container nurseries. Container ("plug") seedlings are grown in small capacity containers in special growth-promoting environments that can produce a shippable seedling in as little as 9 to 12 months.

0010042
Thomas D. 'Tom' Landis
USDA Forest Service

In the temperate zone, container crops are scheduled around the summer solstice when solar energy and temperatures promote rapid growth. Although many container nurseries typically grow one crop per season, some can raise 2 or 3 crops by careful scheduling. The first crop is grown in the greenhouse until outdoor conditions mild enough to move it outside. The second crop is sown just before the summer solstice so the seedling can still benefit from the intense sunlight of early summer, and are left in the greenhouse through the fall.

0010043
Thomas D. 'Tom' Landis
USDA Forest Service

Several different types of propagation structures are used to produce container seedlings. Fully-controlled environments, like this greenhouse, are popular in colder climates, and have permanent roof and sides and a full range of environmental control equipment. Fully-controlled greenhouses are sometimes used to produce more than one crop per year.

0010044
Thomas D. 'Tom' Landis
USDA Forest Service

Semi-controlled environments, like this shelterhouse, have sides which can be rolled-up to promote better cross ventilation. Shelterhouses produce one crop per season, and the seedlings benefit from exposure to ambient conditions during the Hardening Phase.

0010045
Thomas D. 'Tom' Landis
USDA Forest Service

In milder climates, container seedlings can be grown in outdoor compounds. These areas are covered with gravel and porous tarps to control weed growth, and the seedlings are raised on the ground or on tables. Although temperatures cannot be controlled, the crop has the benefit of irrigation, fertilization, and, at this nursery, photoperiodic lighting.

0010046
Thomas D. 'Tom' Landis
USDA Forest Service

There are many different types of containers which range in capacity from 16 cm3 cc (1 in3 ) to 492 cm3 (30 in3) or even larger. Common container types include styrofoam blocks, book planters, and several types made of molded rigid plastic.

0010047
Thomas D. 'Tom' Landis
USDA Forest Service

The best type of container is a function of available nursery equipment, the species of plant, and the conditions at the outplanting site. Conifer species can be grown in relatively small containers whereas large-leaved hardwoods require larger containers. Seedling customers prefer smaller containers for moist outplanting sites, but demand larger, deeper containers for harsh dry conditions.

0010048
Thomas D. 'Tom' Landis
USDA Forest Service

New types of containers are continually being developed. Some have special ventilation holes between cells, wheras others feature a copper coating in the cavity to chemically root prune the seedlings.

0010049
Thomas D. 'Tom' Landis
USDA Forest Service

Most containers can be used for more than one growing season, and so they must be cleaned and sterilized between crops. Chemical disinfectants or hot water can be used to kill weed seeds, fungal spores, or insect eggs on the used containers.

0010050
Thomas D. 'Tom' Landis
USDA Forest Service

Almost all container nurseries use some type of artificial growing media instead of native soil. An ideal media should be sterile, lightweight, porous, and consistent in quality. Several different brands are commercially available, and most are composed of sphagnum peat moss, vermiculite, and sometimes perlite.

0010051
Thomas D. 'Tom' Landis
USDA Forest Service

Some nurseries mix their own growing media. Larger nurseries have specially-designed mixers for precisely blending the components, but customized equipment like this cement mixer have been used.

0010052
Thomas D. 'Tom' Landis
USDA Forest Service

Some growing media components, like vermiculite and perlite, are inherently sterile but sphagnum moss sometimes contains pathogenic fungi. Chemical fumigants or steam heat are typically used for media sterilization.

0010053
Thomas D. 'Tom' Landis
USDA Forest Service

Fertilizers or other chemical amendments are sometimes added to growing media during the mixing process. Dolomite is used to supply calcium and magnesium and raise the low pH. Slow-release fertilizers are composed of resin-coated pellets which release the mineral nutrients as a function of temperature and moisture.

0010054
Thomas D. 'Tom' Landis
USDA Forest Service

Containers are filled with growing media in several different ways. Smaller nurseries fill the containers by hand, but automated filling machines do everything from filling and tamping the media to sowing and covering the seed.

0010055
Thomas D. 'Tom' Landis
USDA Forest Service

The filled containers can be sown by hand or with different sowing machines. The shutterbox consists of a template with a set of holes which correspond to the pattern of the individual container cavities, and can seed 50 containers at one time.

0010056
Thomas D. 'Tom' Landis
USDA Forest Service

The operator fills all the offset holes on the shutter with seed. When the shutter is moved so that it corresponds to the holes in the shutterbox, the seeds fall through into the containers. The size of the holes in the shutter control the sowing rate, usually from 2 to 6 seeds per hole depending on seed quality.

0010057
Thomas D. 'Tom' Landis
USDA Forest Service

Precision sowing machines can accurately control the sowing density down to one seed per cavity. Although expensive, these machines can speed up the sowing process, save valuable seed, and greatly reduce the need for thinning.

0010058
Thomas D. 'Tom' Landis
USDA Forest Service

The final stage in the sowing process consists of covering the sown seed with some type of mulch, such as perlite, grit, or coarse vermiculite. Light-colored mulches are preferred because they reflect sunlight and therefore do not heat-up as much as darker materials.

0010059
Thomas D. 'Tom' Landis
USDA Forest Service

After they are sown, the seedlings are moved out into the growing area. Many container nurseries place the containers on specially-designed benches that promote air pruning of the roots. Some benches are constructed on rollers so that they can be moved together when access is not required. This feature is popular because less valuable growing space is wasted.

0010060
Thomas D. 'Tom' Landis
USDA Forest Service

Just as in bareroot nurseries, the identification of each seed lot is carefully monitored during the nursery process. Different seed lots are sown at the same time, and their location in the nursery is carefully marked and labeled with the proper seed source identification code.

0010061
Thomas D. 'Tom' Landis
USDA Forest Service

Seed germination takes from 2 to 4 weeks and, in the case of multiple seed sowing, many containers have more than one germinant per cell. Most growers feel that oversowing is justified because it is considered more economical to waste a little seed rather than tolerate empty containers which waste valuable growing space. Resowing empty containers is an option, but later-sown seedlings are often overtopped by their neighbors and remain stunted.

0010062
Thomas D. 'Tom' Landis
USDA Forest Service

After seed germination is complete, crews of workers thin multiple germinants down to one per cell. Extra seedlings are either pulled or clipped, depending on their size. Larger seedlings must be clipped because, if they are pulled, they may uproot the crop seedling.

0010063
Thomas D. 'Tom' Landis
USDA Forest Service

Once thinning is complete, seedlings are brought into the Rapid Growth Phase, in which they are forced into accelerated growth rates by supplying all the factors that are normally limiting. The type of growing environment will determine the cultural options that are available and the resultant growth rate. Fully-controlled environments have heating, ventilation, photoperiodic lighting, irrigation, fertilization, and even supplemental carbon dioxide.

0010064
Thomas D. 'Tom' Landis
USDA Forest Service

Many nurseries use under-bench heating which stimulates seedling growth by warming the roots system. These systems also can be used to force ventilation up through the seedling foliage and significantly reduces incidence of foliar diseases, such as grey mold. The major drawback of underbench systems is that the tubes prohibit the use of forklifts in the greenhouse.

0010065
Thomas D. 'Tom' Landis
USDA Forest Service

Eliminating water stress is crucial to achieving good seedling growth and container nurseries use either stationary or mobile overhead irrigation systems. Stationary systems consist of sprinkler heads set in a regular pattern whereas mobile systems have a horizontally-mounted boom that moves back and forth, delivering a uniform amount of water to the crop.

0010066
Thomas D. 'Tom' Landis
USDA Forest Service

Determining when and how much to irrigate in particularly difficult in a container nursery because seedlings use up water quickly in small containers, where it is difficult to directly observe moisture conditions. The best irrigation monitoring technique is to weigh the containers between irrigations because the relative wetness of the growing media can be correlated to the container weight.

0010067
Thomas D. 'Tom' Landis
USDA Forest Service

Most container tree nurseries fertilize through the irrigation system. Liquid fertilizer solutions are injected into the irrigation lines in the headhouse, and applied to the crop through the sprinkler nozzles. Supplying all 13 essential mineral nutrient is one of the most effective cultural techniques for controlling seedling growth, and nutrient injection systems are very effective because they supply the proper nutrient concentration at exactly the right time.

0010068
Thomas D. 'Tom' Landis
USDA Forest Service

Although most container tree nurseries produce only seedlings, some rooted cuttings are being grown for special purposes, such as tree improvement. These coast redwood mother plants will provide cuttings of trees selected for fast growth and good wood characteristics. Cuttings are also used when seed from a particular seed zone is scarce.

0010069
Thomas D. 'Tom' Landis
USDA Forest Service

At the end of the Rapid Growth Phase, when container seedlings have reached their desired height, the growing environment is changed to initiate the Hardening Phase.

0010070
Thomas D. 'Tom' Landis
USDA Forest Service

The most critical environmental factors for inducing hardiness and dormancy are cooler temperatures, a mild moisture and nutrient stress, and a shorter photoperiod.

0010071
Thomas D. 'Tom' Landis
USDA Forest Service

Seedlings in fully-enclosed greenhouses are often moved to a shadehouse where the change in temperature and humidity aid the hardening process. Other nurseries remove the greenhouse covering during the latter part of the growing season to expose the crop to ambient conditions.

0010072
Thomas D. 'Tom' Landis
USDA Forest Service

Cold hardiness tests can be used to determine when the seedlings are ready for harvesting, because research has shown that these tests are a good indication of overall hardiness and dormancy.

0010073
Thomas D. 'Tom' Landis
USDA Forest Service

Seedling roots and the cambium around the root collar are much less cold tolerant that the shoots, and can be damaged or even killed at temperatures that are only a few degrees below freezing.

0010074
Thomas D. 'Tom' Landis
USDA Forest Service

Some nurseries store their container seedlings outside overwinter, being particularly careful to place the seedlings on the ground and insulate the root systems against cold.

0010075
Thomas D. 'Tom' Landis
USDA Forest Service

Some container tree nurseries ship their seedling directly to the outplanting site in the growth container. This technique is necessary where cold storage facilities are not available, but the seedlings must still be protected and maintained on the outplanting site.

0010076
Thomas D. 'Tom' Landis
USDA Forest Service

Other nurseries pull the seedlings from the growth container, and wrap them in bundles. The bundles are placed in moisture proof boxes, and stored under refrigeration. Container seedling can also be freezer stored, and treated essentially the same as bareroot stock.

0010077
Thomas D. 'Tom' Landis
USDA Forest Service

A relatively-new stock type is known as a "plug transplant", which is produced by transplanting a small container seedling into the bareroot nursery for an additional year of growth.

0010078
Thomas D. 'Tom' Landis
USDA Forest Service

Plug transplants are cultured and harvested exactly the same as bareroot transplant stock. These seedlings have phenomenal growth rates and are preferred by customers that want a large seedling with a fibrous root system.

0010079
Thomas D. 'Tom' Landis
USDA Forest Service

Some customers are concerned about the possibility of poor root development from container seedlings after they are outplanted. This is usually only a problem with stock that has been left too long in the container and has become root-bound, when they are planted with the wrong type of implement, or in heavy clay soils.

0010080
Thomas D. 'Tom' Landis
USDA Forest Service

In conclusion, both bareroot and container seedling have a place in modern reforestation. The choice of which type of seedling to use will depend on the available nursery system, the nursery climate, and the conditions on the outplanting site.