Friday, January 22, 2016

The Wetland Garden- Sally Manifold, MS

Choose a place you know to be wet already.

Observe your property/restoration area during all seasons, watching for standing water in winter.  Mark the high-water line. Decide how large your planting will be.

An alternate way to determine a wetland boundary in even a dry season is to dig soil test holes (~12-18” deep).  Look for black organic soil/peat, or gray soils interspersed with red mottling.  These are indicators of saturated soil conditions where wetland plants thrive.

Order wetland plants, bare root or potted, for delivery in fall. Match species to your conditions: emergent plants for sites with year round standing water, or species tolerant of summer drought for seasonal wetlands. Sun and shade also affect species choices.

To remove existing undesired vegetation, spray with Roundup (Glyphosate) during the dry season when grasses and weeds are actively growing. Use Rodeo, the formulation for use near water, for sites with permanent standing water. For small just-soggy areas, sheet mulching with cardboard and wood chips can kill lawn plants.  This will take a longer time, for instance over a fall-winter-spring, for the cardboard to rot. 

After the grass has died, you may see regrowth of mosses (as rains begin), and taprooted weeds like dandelions. Dig deep to remove weed roots.  Be glad for surviving moss, as it creates a ground cover and prevents weed seed germination.

Plan your plantings, creating blocks of the same species, rather than a scattering of different plants.  Make a network of paths to access the area, marked with wood chips or straw.  These will help in maintenance and enjoyment.

In the fall, plant new plants into the dead vegetation and moss, or through the wood chip mulch. Space generously, as wetland plants will spread via clump enlargement or runners. Tall plants can have lower groundcovers planted underneath.

Mark very small or dormant plants with flags, as they can be easily walked on or planted on top of.

During the winter, frost may heave small new plants out of the ground - gently replant them after each thaw.

In spring, begin watching and weeding.  The seedbank from previous vegetation can be infinite.  Choose your battles.  Perhaps remove only the larger weeds that threaten desired plants.  Depends on the time and energy you can devote, and your goals. Adding wood chip mulch can suppress many weeds. Annual weed seedlings can be knocked back with a spray of white vinegar, but roots of more vigorous plants will not be killed this way.  Hand weeding is often the best method.

Observe the new plant community, as it sorts out which species will dominate.  “Edit” the species to suit your goals.  Aggressive species can be dug out, or sprayed in the dry season with Roundup, protecting surrounding vegetation with a shield of cardboard, etc.

Add new species among your plantings, especially shade tolerant herbaceous plants, such as lady ferns, under shrubs.  Watch for interesting volunteers, appearing from dormant seeds from historical wetland communities on site, or from water transport from upstream.  If unsure what something is, allow it to grow until you can ID it and decide if you want it.  Cattails will appear!  Probably not a good idea in a small wetland planting, as they will take over everything. Dig them when small, as they quickly start spreading by rhizomes. Willows also arrive by air and grow fast.

As the wetland fills in with plants, your paths may be overrun.  You can either dig and move plants crowding the path, or relocate or abandon that path.  Weeding maintenance sometimes requires wading through thick plants anyway, “off-trail” so to speak, and this is not that hard.

Enjoy your new ecosystem, especially as it changes over the year and with the passage of time. As it (hopefully) requires less work, you can think about an upland native plant buffer to enlarge your natural area.


No comments:

Post a Comment