publication "Sustainable Trees and Shrubs," a 48-page
document containing a list of sustainable plants, including drawings
and comprehensive indices, is available in PDF format or may be
purchased from the URI Cooperative Extension Education Center by
calling (401) 874-2900.
Sustainable Trees & Shrubs List in PDF Format
lists are invaluable resources for garden enthusiasts, designers,
nursery trades people and landscape architects. We constantly consult
books and nursery catalogs which list landscape plants, especially
those that organize plants by their characteristics and landscape
uses. As times and fashions change, new plants emerge, old plants
are rediscovered, and others lose favor and disappear from these
lists. But one point remains clear: listing plants encourages their
widespread distribution and use. The purpose of this publication
is to encourage the production and use of landscape plants that
are more sustainable: those which are not invasive and require reduced
inputs of pesticides, water and maintenance.
Not long ago, plants from around the world could be introduced into
the landscape and provided with the care needed to ensure their
long-term beauty and success. Pesticide use was widespread and its
effectiveness unquestioned, labor for intensive care was available
and affordable, and the supply of natural resources was considered
limitless. Much has changed in recent decades; we have become painfully
aware of the limits of our natural resources and the precarious
balance of nature in which we play a pivotal role. Many in our society
are looking for ways to reduce human impacts on the environment.
Others lack the time or resources to manage pests or maintain shrubs
that require frequent pruning or irrigation. These people should
find the sustainable plant list an invaluable resource.
plant selection is the key first step in developing a balanced and
self-perpetuating landscape. However, plant survival with minimal
maintenance is not the only issue in sustainability. We are having
more difficulty with invasive exotic plants which have escaped from
managed land-scapes, displacing native plants and disrupting natural
ecosystems. The use of these potential invasives cannot be seen
as sustainable except in very controlled situations.
list of sustainable plants is not offered as the entire answer.
Proper siting, planting and maintenance are necessary for a plant
to prosper in the landscape. Therefore, climatic conditions, exposure
to sun and wind, subsurface soil and moisture conditions, etc. must
be considered when selecting plants for a particular location. Sustainable
or not, if one ignores the site and a plant's cultural requirements,
that plant will suffer.
In preparing this list and the accompanying plant descriptions,
we have targeted a professional audience, with an expectation that
through time, as these plants become more available, this information
will filter down to the consumers. Plants on this list are proven
performers in Southern New England (USDA Hardiness Zones 7a - 5b),
and many of them can be grown both north and south of here (although
the pest complexes might change). This list is dynamic and will
continue to change as new plants and pests are introduced and as
we learn more about existing ones.
list is only a guide. Plants are included which have qualities appealing
to designers and plant lovers alike. Plant descriptions include
color, form, texture and growth habits as well as maintenance requirements
and hardiness. Many of the plants on the list are well known and
currently in production, while others need to be grown and distributed
more. We are well aware that it will take a decade or more before
some of the newer plants are readily available in the trade.
of our favorite plants are not on the list, because serious pests
threaten their existence or their maintenance requirements are too
high for them to be considered sustainable. That doesn't mean that
we won't include a few of them in our landscapes. Life would be
indeed dull without a rose, but most of us would not want to maintain
a half-acre of them. Plants with occasional pest problems or those
with relatively minor problems are included on the list with cautionary
notes. It is only those plants with life-threatening or chronic
pest problems that are omitted from the list, along with seriously
invasive species. The list is not intended to eliminate the production
of high maintenance plants with desirable traits. Instead, it is
intended to encourage the broader distribution of plants which seem
to be better suited to satisfying not only our horticultural requirements,
but also our environmental concerns.
There is renewed interest in native plants (those found growing
outside of cultivation in this region during pre-Colonial times)
which often are better acclimated, less pest prone and more favorable
for native wildlife than exotic plants. Native plants are identified
in Appendix 2. However, it should be noted that many exotic insect
and disease pests have been introduced in the past 300 years. They
have virtually eliminated some of our native plants and become serious
pests of others. In these cases, it is useful to look to other parts
of the world where plants have evolved resistance to these pests.
Even without introduced pests, some native plants have problems
in our landscapes where they are far removed from their natural
environments. A fabulous forest shrub can have serious difficulties
when sited between a driveway and a sidewalk. It is likely that
a sustainable landscape will feature many native plants, but we
think there are many non-natives which should be considered as well.