Appendix B: Bioengineering for Streambank Erosion Control -- Guidelines
Herbaceous Plants. Plant handling requirements of herbaceous plants are even more
rigorous than woody plants as a general rule because they are usually obtained in the spring
when nurseries have them ready to ship or when they are readily identified in the wild for
collection. At those times, they are very susceptible to dessication mortality. Consequently,
they must be kept in a moist, shaded condition, or even better, in water-filled containers from
the time of collection from the wild or receipt from the nursery to the time of transplanting.
If herbaceous plants are identified and tagged for collection in the spring or summer, they can
be collected when dormant in the late fall or winter. During those times, they can be handled
more freely, but should still be prevented from drying out. When transporting from the
nursery, holding, or harvesting area to the project site, this should be in a covered vehicle.
If the weather is very hot, cooling from ice or refrigeration may be necessary. Exposure to
high winds should be avoided. Plants can be placed in a water-filled ditch and covered with
soil in a shaded area for storage of several days while awaiting planting. It is best not to store
plants longer than necessary, and delivery should be scheduled to match planting dates.
If herbaceous plants are to be grown, they will need to be grown from seed or from
collected rhizomes, tubers, or rooted stems or rootstock from the wild. Most wetland plant
seed needs to be stratified and will not germinate under water even after stratification. An
experienced wetlands nursery person should be consulted before attempting to grow wetland
plants from seed. Often, a cold treatment under water is necessary for stratification (Pierce,
1994). There are various other stratification methods of wetland plants, such as hot and cold
temperature treatments and treatments with various fertilizers. Rhizomes, tubers, and rooted
stems and rootstock of wetland herbaceous plants can be grown out in wet troughs or ditches
and ponds containing fertilized sand and peat moss. Only enough water is necessary to keep
the rhizomes, tubers, etc. from drying out. Plants can be grown out in the greenhouse over
colder months, but will require hardening before transfer to the project site.
Hoag (1994b) stated that hardening off can be accomplished by removing the plants from
the greenhouse and placing them in a cool, partially shaded area for 1-2 weeks. This is
generally a lathe or slat house. Some are constructed with snow fencing which has wooden
slats woven together with wire. According to Hoag (1994b), this type of structure allows a
small amount of direct sunlight and solar radiation through the slats to the plants, but not
enough to burn them. A partially shaded spot near the planting site will also work. It is
important to keep the plants well watered and misted during the hardening off period.
B-77
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