BELOW: Moss is an important element of the roji (teahouse
garden) at the Seattle Japanese Garden. The spread of moss
over time to cover the ground and the trunks of trees is an
example of how gardens can develop lives of their own.
(Photo by Aurora Santiago)
BEFORE
in our borders battle it out for dominance—it’s
perhaps more useful to think of it as an analogy
that can help us anticipate how our gardens will
evolve over time. When we plant a garden, we
usually plant all the different stages of succession
at once—pioneers, perennials and climax plants.
It shouldn’t surprise us, then, when perenni-
als quickly start to push out our annuals, and
trees overshadow and negatively impact nearby
sun-loving perennials and shrubs.
Equipped with this knowledge, we can better
predict changes over time and plant accordingly.
If we know a tree will be casting lots of dense
shade in a given space in a matter of years—or
creating drier soils—we can underplant with
shrubs, perennials and groundcovers that can
adapt to those developing conditions. Trees and
shrubs are the larger, more permanent elements
of the garden, providing continuity and attrac-
tiveness seasonally and over the years. Knowing
their mature size and spread will not only help
you choose plants that don’t outgrow their space
but also create a planting plan of lasting value.
Addressing the Challenges of Time
Even if you anticipate these changes, and take
issues of crowding and encroaching shade into
consideration, it can be difficult to predict
accurately how well and quickly your plants will
8 v Washington Park Arboretum Bulletin
AFTER
grow, or if problems will arise. So many factors
come into play—including weather condi-
tions, pests and diseases—not to mention the
amount of time that you yourself are able to
devote to the garden.
Various strategies can help you address time-
related challenges. Always space your plants
according to their mature spread and height. Your
new garden may have an empty appearance for
a while, but be patient. One way to deal with the
problem is to specify “temporary” plants that will
quickly grow and fill in the spaces but then disap-
pear after a few years. Examples include showy
perennials such Delphinium and Echinacea; short-
lived shrubs and herbs like Hebe and Lavandula;
and low grasses and grass-like plants such as
Festuca, Acorus and Carex. Whether naturally
short-lived or susceptible to being shaded out by
other plants, they won’t be essential to your vision
or your garden’s evolution.
A plant that grows too large or fails to thrive
can be removed, cut back, or replaced by a
younger plant of the same species, until it too
outgrows the space. Dying or unattractive plants